Merge branch '2.0.x'

config/checkstyle/checkstyle-suppressions.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0"?>
+<!DOCTYPE suppressions PUBLIC
+		"-//Checkstyle//DTD SuppressionFilter Configuration 1.2//EN"
+		"https://checkstyle.org/dtds/suppressions_1_2.dtd">
+<suppressions>
+	<suppress files="com[\\/]example[\\/]restassured" checks="IllegalImport" />
+</suppressions>

config/checkstyle/checkstyle.xml

@@ -1,8 +1,16 @@
 <?xml version="1.0"?>
 <!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.3//EN" "https://checkstyle.org/dtds/configuration_1_3.dtd">
 <module name="com.puppycrawl.tools.checkstyle.Checker">
+	<module name="SuppressionFilter">
+		<property name="file" value="${config_loc}/checkstyle-suppressions.xml"/>
+	</module>
 	<module name="io.spring.javaformat.checkstyle.SpringChecks">
 		<property name="avoidStaticImportExcludes" value=" org.springframework.restdocs.cli.CliDocumentation.*"/>
 	</module>
-
+	<module name="com.puppycrawl.tools.checkstyle.TreeWalker">
+		<module name="com.puppycrawl.tools.checkstyle.checks.imports.IllegalImportCheck">
+			<property name="regexp" value="true" />
+			<property name="illegalPkgs" value="^org\.hamcrest.*" />
+		</module>
+	</module>
 </module>

spring-restdocs-asciidoctor/src/test/java/org/springframework/restdocs/asciidoctor/SnippetsDirectoryResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,11 +23,10 @@ import java.util.Map;
 
 import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 import org.junit.rules.TemporaryFolder;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.hamcrest.CoreMatchers.equalTo;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 
 /**
  * Tests for {@link SnippetsDirectoryResolver}.
@@ -39,9 +38,6 @@ public class SnippetsDirectoryResolverTests {
 	@Rule
 	public TemporaryFolder temporaryFolder = new TemporaryFolder();
 
-	@Rule
-	public ExpectedException thrown = ExpectedException.none();
-
 	@Test
 	public void mavenProjectsUseTargetGeneratedSnippetsRelativeToDocdir() throws IOException {
 		this.temporaryFolder.newFile("pom.xml");
@@ -57,17 +53,15 @@ public class SnippetsDirectoryResolverTests {
 		Map<String, Object> attributes = new HashMap<>();
 		String docdir = new File(this.temporaryFolder.getRoot(), "src/main/asciidoc").getAbsolutePath();
 		attributes.put("docdir", docdir);
-		this.thrown.expect(IllegalStateException.class);
-		this.thrown.expectMessage(equalTo("pom.xml not found in '" + docdir + "' or above"));
-		getMavenSnippetsDirectory(attributes);
+		assertThatIllegalStateException().isThrownBy(() -> getMavenSnippetsDirectory(attributes))
+				.withMessage("pom.xml not found in '" + docdir + "' or above");
 	}
 
 	@Test
 	public void illegalStateWhenDocdirAttributeIsNotSetInMavenProject() throws IOException {
 		Map<String, Object> attributes = new HashMap<>();
-		this.thrown.expect(IllegalStateException.class);
-		this.thrown.expectMessage(equalTo("docdir attribute not found"));
-		getMavenSnippetsDirectory(attributes);
+		assertThatIllegalStateException().isThrownBy(() -> getMavenSnippetsDirectory(attributes))
+				.withMessage("docdir attribute not found");
 	}
 
 	@Test
@@ -100,9 +94,9 @@ public class SnippetsDirectoryResolverTests {
 	@Test
 	public void illegalStateWhenGradleProjectdirAndProjectdirAttributesAreNotSetInGradleProject() throws IOException {
 		Map<String, Object> attributes = new HashMap<>();
-		this.thrown.expect(IllegalStateException.class);
-		this.thrown.expectMessage(equalTo("projectdir attribute not found"));
-		new SnippetsDirectoryResolver().getSnippetsDirectory(attributes);
+		assertThatIllegalStateException()
+				.isThrownBy(() -> new SnippetsDirectoryResolver().getSnippetsDirectory(attributes))
+				.withMessage("projectdir attribute not found");
 	}
 
 	private File getMavenSnippetsDirectory(Map<String, Object> attributes) {

spring-restdocs-core/build.gradle

@@ -63,8 +63,6 @@ dependencies {
 	testImplementation("org.assertj:assertj-core")
 	testImplementation("org.javamoney:moneta")
 	testImplementation("org.mockito:mockito-core")
-	testImplementation("org.hamcrest:hamcrest-core")
-	testImplementation("org.hamcrest:hamcrest-library")
 	testImplementation("org.springframework:spring-test")
 
 	testRuntimeOnly("org.glassfish:jakarta.el:4.0.2")

spring-restdocs-core/src/test/java/org/springframework/restdocs/headers/RequestHeadersSnippetFailureTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,14 +21,12 @@ import java.util.Arrays;
 
 import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 
 import org.springframework.restdocs.snippet.SnippetException;
 import org.springframework.restdocs.templates.TemplateFormats;
 import org.springframework.restdocs.testfixtures.OperationBuilder;
 
-import static org.hamcrest.CoreMatchers.endsWith;
-import static org.hamcrest.CoreMatchers.equalTo;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.springframework.restdocs.headers.HeaderDocumentation.headerWithName;
 
 /**
@@ -42,25 +40,21 @@ public class RequestHeadersSnippetFailureTests {
 	@Rule
 	public OperationBuilder operationBuilder = new OperationBuilder(TemplateFormats.asciidoctor());
 
-	@Rule
-	public ExpectedException thrown = ExpectedException.none();
-
 	@Test
 	public void missingRequestHeader() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				equalTo("Headers with the following names were not found" + " in the request: [Accept]"));
-		new RequestHeadersSnippet(Arrays.asList(headerWithName("Accept").description("one")))
-				.document(this.operationBuilder.request("http://localhost").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestHeadersSnippet(Arrays.asList(headerWithName("Accept").description("one")))
+						.document(this.operationBuilder.request("http://localhost").build()))
+				.withMessage("Headers with the following names were not found in the request: [Accept]");
 	}
 
 	@Test
 	public void undocumentedRequestHeaderAndMissingRequestHeader() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				endsWith("Headers with the following names were not found" + " in the request: [Accept]"));
-		new RequestHeadersSnippet(Arrays.asList(headerWithName("Accept").description("one")))
-				.document(this.operationBuilder.request("http://localhost").header("X-Test", "test").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestHeadersSnippet(Arrays.asList(headerWithName("Accept").description("one")))
+						.document(this.operationBuilder.request("http://localhost").header("X-Test", "test").build()))
+				.withMessageEndingWith("Headers with the following names were not found in the request: [Accept]");
+
 	}
 
 }

spring-restdocs-core/src/test/java/org/springframework/restdocs/headers/ResponseHeadersSnippetFailureTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,14 +21,12 @@ import java.util.Arrays;
 
 import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 
 import org.springframework.restdocs.snippet.SnippetException;
 import org.springframework.restdocs.templates.TemplateFormats;
 import org.springframework.restdocs.testfixtures.OperationBuilder;
 
-import static org.hamcrest.CoreMatchers.endsWith;
-import static org.hamcrest.CoreMatchers.equalTo;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.springframework.restdocs.headers.HeaderDocumentation.headerWithName;
 
 /**
@@ -42,25 +40,21 @@ public class ResponseHeadersSnippetFailureTests {
 	@Rule
 	public OperationBuilder operationBuilder = new OperationBuilder(TemplateFormats.asciidoctor());
 
-	@Rule
-	public ExpectedException thrown = ExpectedException.none();
-
 	@Test
 	public void missingResponseHeader() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				equalTo("Headers with the following names were not found" + " in the response: [Content-Type]"));
-		new ResponseHeadersSnippet(Arrays.asList(headerWithName("Content-Type").description("one")))
-				.document(this.operationBuilder.response().build());
+		assertThatExceptionOfType(SnippetException.class).isThrownBy(
+				() -> new ResponseHeadersSnippet(Arrays.asList(headerWithName("Content-Type").description("one")))
+						.document(this.operationBuilder.response().build()))
+				.withMessage("Headers with the following names were not found" + " in the response: [Content-Type]");
 	}
 
 	@Test
 	public void undocumentedResponseHeaderAndMissingResponseHeader() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				endsWith("Headers with the following names were not found" + " in the response: [Content-Type]"));
-		new ResponseHeadersSnippet(Arrays.asList(headerWithName("Content-Type").description("one")))
-				.document(this.operationBuilder.response().header("X-Test", "test").build());
+		assertThatExceptionOfType(SnippetException.class).isThrownBy(
+				() -> new ResponseHeadersSnippet(Arrays.asList(headerWithName("Content-Type").description("one")))
+						.document(this.operationBuilder.response().header("X-Test", "test").build()))
+				.withMessageEndingWith(
+						"Headers with the following names were not found in the response: [Content-Type]");
 	}
 
 }

spring-restdocs-core/src/test/java/org/springframework/restdocs/hypermedia/LinksSnippetFailureTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,13 +22,12 @@ import java.util.Collections;
 
 import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 
 import org.springframework.restdocs.snippet.SnippetException;
 import org.springframework.restdocs.templates.TemplateFormats;
 import org.springframework.restdocs.testfixtures.OperationBuilder;
 
-import static org.hamcrest.CoreMatchers.equalTo;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 
 /**
  * Tests for failures when rendering {@link LinksSnippet} due to missing or undocumented
@@ -41,42 +40,40 @@ public class LinksSnippetFailureTests {
 	@Rule
 	public OperationBuilder operationBuilder = new OperationBuilder(TemplateFormats.asciidoctor());
 
-	@Rule
-	public ExpectedException thrown = ExpectedException.none();
-
 	@Test
 	public void undocumentedLink() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Links with the following relations were not" + " documented: [foo]"));
-		new LinksSnippet(new StubLinkExtractor().withLinks(new Link("foo", "bar")),
-				Collections.<LinkDescriptor>emptyList()).document(this.operationBuilder.build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new LinksSnippet(new StubLinkExtractor().withLinks(new Link("foo", "bar")),
+						Collections.<LinkDescriptor>emptyList()).document(this.operationBuilder.build()))
+				.withMessage("Links with the following relations were not documented: [foo]");
 	}
 
 	@Test
 	public void missingLink() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				equalTo("Links with the following relations were not" + " found in the response: [foo]"));
-		new LinksSnippet(new StubLinkExtractor(), Arrays.asList(new LinkDescriptor("foo").description("bar")))
-				.document(this.operationBuilder.build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new LinksSnippet(new StubLinkExtractor(),
+						Arrays.asList(new LinkDescriptor("foo").description("bar")))
+								.document(this.operationBuilder.build()))
+				.withMessage("Links with the following relations were not found in the response: [foo]");
 	}
 
 	@Test
 	public void undocumentedLinkAndMissingLink() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Links with the following relations were not"
-				+ " documented: [a]. Links with the following relations were not" + " found in the response: [foo]"));
-		new LinksSnippet(new StubLinkExtractor().withLinks(new Link("a", "alpha")),
-				Arrays.asList(new LinkDescriptor("foo").description("bar"))).document(this.operationBuilder.build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new LinksSnippet(new StubLinkExtractor().withLinks(new Link("a", "alpha")),
+						Arrays.asList(new LinkDescriptor("foo").description("bar")))
+								.document(this.operationBuilder.build()))
+				.withMessage("Links with the following relations were not documented: [a]. Links with the following"
+						+ " relations were not found in the response: [foo]");
 	}
 
 	@Test
 	public void linkWithNoDescription() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("No description was provided for the link with rel 'foo' and no"
-				+ " title was available from the link in the payload"));
-		new LinksSnippet(new StubLinkExtractor().withLinks(new Link("foo", "bar")),
-				Arrays.asList(new LinkDescriptor("foo"))).document(this.operationBuilder.build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new LinksSnippet(new StubLinkExtractor().withLinks(new Link("foo", "bar")),
+						Arrays.asList(new LinkDescriptor("foo"))).document(this.operationBuilder.build()))
+				.withMessage("No description was provided for the link with rel 'foo' and no title was available"
+						+ " from the link in the payload");
 	}
 
 }

spring-restdocs-core/src/test/java/org/springframework/restdocs/operation/QueryStringParserTests.java

@@ -19,12 +19,10 @@ package org.springframework.restdocs.operation;
 import java.net.URI;
 import java.util.Arrays;
 
-import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.hamcrest.CoreMatchers.equalTo;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 
 /**
  * Tests for {@link QueryStringParser}.
@@ -33,9 +31,6 @@ import static org.hamcrest.CoreMatchers.equalTo;
  */
 public class QueryStringParserTests {
 
-	@Rule
-	public ExpectedException thrown = ExpectedException.none();
-
 	private final QueryStringParser queryStringParser = new QueryStringParser();
 
 	@Test
@@ -76,9 +71,9 @@ public class QueryStringParserTests {
 
 	@Test
 	public void malformedParameter() {
-		this.thrown.expect(IllegalArgumentException.class);
-		this.thrown.expectMessage(equalTo("The parameter 'a=apple=avocado' is malformed"));
-		this.queryStringParser.parse(URI.create("http://localhost?a=apple=avocado"));
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> this.queryStringParser.parse(URI.create("http://localhost?a=apple=avocado")))
+				.withMessage("The parameter 'a=apple=avocado' is malformed");
 	}
 
 	@Test

spring-restdocs-core/src/test/java/org/springframework/restdocs/operation/preprocess/PrettyPrintingContentModifierTests.java

@@ -23,10 +23,9 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import org.junit.Rule;
 import org.junit.Test;
 
-import org.springframework.restdocs.testfixtures.OutputCapture;
+import org.springframework.restdocs.testfixtures.OutputCaptureRule;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.hamcrest.Matchers.isEmptyString;
 
 /**
  * Tests for {@link PrettyPrintingContentModifier}.
@@ -37,7 +36,7 @@ import static org.hamcrest.Matchers.isEmptyString;
 public class PrettyPrintingContentModifierTests {
 
 	@Rule
-	public OutputCapture outputCapture = new OutputCapture();
+	public OutputCaptureRule outputCapture = new OutputCaptureRule();
 
 	@Test
 	public void prettyPrintJson() throws Exception {
@@ -61,17 +60,17 @@ public class PrettyPrintingContentModifierTests {
 	@Test
 	public void nonJsonAndNonXmlContentIsHandledGracefully() throws Exception {
 		String content = "abcdefg";
-		this.outputCapture.expect(isEmptyString());
 		assertThat(new PrettyPrintingContentModifier().modifyContent(content.getBytes(), null))
 				.isEqualTo(content.getBytes());
+		assertThat(this.outputCapture).isEmpty();
 	}
 
 	@Test
 	public void nonJsonContentThatInitiallyLooksLikeJsonIsHandledGracefully() throws Exception {
 		String content = "\"abc\",\"def\"";
-		this.outputCapture.expect(isEmptyString());
 		assertThat(new PrettyPrintingContentModifier().modifyContent(content.getBytes(), null))
 				.isEqualTo(content.getBytes());
+		assertThat(this.outputCapture).isEmpty();
 	}
 
 	@Test

spring-restdocs-core/src/test/java/org/springframework/restdocs/payload/RequestFieldsSnippetFailureTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,7 +22,6 @@ import java.util.Collections;
 
 import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
@@ -30,9 +29,7 @@ import org.springframework.restdocs.snippet.SnippetException;
 import org.springframework.restdocs.templates.TemplateFormats;
 import org.springframework.restdocs.testfixtures.OperationBuilder;
 
-import static org.hamcrest.CoreMatchers.endsWith;
-import static org.hamcrest.CoreMatchers.equalTo;
-import static org.hamcrest.CoreMatchers.startsWith;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.springframework.restdocs.payload.PayloadDocumentation.fieldWithPath;
 
 /**
@@ -46,148 +43,145 @@ public class RequestFieldsSnippetFailureTests {
 	@Rule
 	public OperationBuilder operationBuilder = new OperationBuilder(TemplateFormats.asciidoctor());
 
-	@Rule
-	public ExpectedException thrown = ExpectedException.none();
-
 	@Test
 	public void undocumentedRequestField() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(startsWith("The following parts of the payload were not" + " documented:"));
-		new RequestFieldsSnippet(Collections.<FieldDescriptor>emptyList())
-				.document(this.operationBuilder.request("http://localhost").content("{\"a\": 5}").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(Collections.<FieldDescriptor>emptyList())
+						.document(this.operationBuilder.request("http://localhost").content("{\"a\": 5}").build()))
+				.withMessageStartingWith("The following parts of the payload were not documented:");
 	}
 
 	@Test
 	public void missingRequestField() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Fields with the following paths were not found" + " in the payload: [a.b]"));
-		new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a.b").description("one")))
-				.document(this.operationBuilder.request("http://localhost").content("{}").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a.b").description("one")))
+						.document(this.operationBuilder.request("http://localhost").content("{}").build()))
+				.withMessage("Fields with the following paths were not found in the payload: [a.b]");
 	}
 
 	@Test
 	public void missingOptionalRequestFieldWithNoTypeProvided() throws IOException {
-		this.thrown.expect(FieldTypeRequiredException.class);
-		new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a.b").description("one").optional()))
-				.document(this.operationBuilder.request("http://localhost").content("{ }").build());
+		assertThatExceptionOfType(FieldTypeRequiredException.class).isThrownBy(
+				() -> new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a.b").description("one").optional()))
+						.document(this.operationBuilder.request("http://localhost").content("{ }").build()));
 	}
 
 	@Test
 	public void undocumentedRequestFieldAndMissingRequestField() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(startsWith("The following parts of the payload were not" + " documented:"));
-		this.thrown
-				.expectMessage(endsWith("Fields with the following paths were not found" + " in the payload: [a.b]"));
-		new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a.b").description("one")))
-				.document(this.operationBuilder.request("http://localhost").content("{ \"a\": { \"c\": 5 }}").build());
+		assertThatExceptionOfType(SnippetException.class).isThrownBy(
+				() -> new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a.b").description("one"))).document(
+						this.operationBuilder.request("http://localhost").content("{ \"a\": { \"c\": 5 }}").build()))
+				.withMessageStartingWith("The following parts of the payload were not documented:")
+				.withMessageEndingWith("Fields with the following paths were not found in the payload: [a.b]");
 	}
 
 	@Test
 	public void attemptToDocumentFieldsWithNoRequestBody() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Cannot document request fields as the request body is empty"));
-		new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one")))
-				.document(this.operationBuilder.request("http://localhost").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one")))
+						.document(this.operationBuilder.request("http://localhost").build()))
+				.withMessage("Cannot document request fields as the request body is empty");
 	}
 
 	@Test
 	public void fieldWithExplicitTypeThatDoesNotMatchThePayload() throws IOException {
-		this.thrown.expect(FieldTypesDoNotMatchException.class);
-		this.thrown.expectMessage(
-				equalTo("The documented type of the field 'a' is" + " Object but the actual type is Number"));
-		new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one").type(JsonFieldType.OBJECT)))
-				.document(this.operationBuilder.request("http://localhost").content("{ \"a\": 5 }").build());
+		assertThatExceptionOfType(FieldTypesDoNotMatchException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(
+						Arrays.asList(fieldWithPath("a").description("one").type(JsonFieldType.OBJECT))).document(
+								this.operationBuilder.request("http://localhost").content("{ \"a\": 5 }").build()))
+				.withMessage("The documented type of the field 'a' is Object but the actual type is Number");
 	}
 
 	@Test
 	public void fieldWithExplicitSpecificTypeThatActuallyVaries() throws IOException {
-		this.thrown.expect(FieldTypesDoNotMatchException.class);
-		this.thrown.expectMessage(
-				equalTo("The documented type of the field '[].a' is" + " Object but the actual type is Varies"));
-		new RequestFieldsSnippet(Arrays.asList(fieldWithPath("[].a").description("one").type(JsonFieldType.OBJECT)))
-				.document(this.operationBuilder.request("http://localhost").content("[{ \"a\": 5 },{ \"a\": \"b\" }]")
-						.build());
+		assertThatExceptionOfType(FieldTypesDoNotMatchException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(
+						Arrays.asList(fieldWithPath("[].a").description("one").type(JsonFieldType.OBJECT)))
+								.document(this.operationBuilder.request("http://localhost")
+										.content("[{ \"a\": 5 },{ \"a\": \"b\" }]").build()))
+				.withMessage("The documented type of the field '[].a' is Object but the actual type is Varies");
 	}
 
 	@Test
 	public void undocumentedXmlRequestField() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(startsWith("The following parts of the payload were not documented:"));
-		new RequestFieldsSnippet(Collections.<FieldDescriptor>emptyList())
-				.document(this.operationBuilder.request("http://localhost").content("<a><b>5</b></a>")
-						.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(Collections.<FieldDescriptor>emptyList())
+						.document(this.operationBuilder.request("http://localhost").content("<a><b>5</b></a>")
+								.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build()))
+				.withMessageStartingWith("The following parts of the payload were not documented:");
 	}
 
 	@Test
 	public void xmlDescendentsAreNotDocumentedByFieldDescriptor() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(startsWith("The following parts of the payload were not documented:"));
-		new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a").type("a").description("one")))
-				.document(this.operationBuilder.request("http://localhost").content("<a><b>5</b></a>")
-						.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(
+						() -> new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a").type("a").description("one")))
+								.document(this.operationBuilder.request("http://localhost").content("<a><b>5</b></a>")
+										.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build()))
+				.withMessageStartingWith("The following parts of the payload were not documented:");
 	}
 
 	@Test
 	public void xmlRequestFieldWithNoType() throws IOException {
-		this.thrown.expect(FieldTypeRequiredException.class);
-		new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one")))
-				.document(this.operationBuilder.request("http://localhost").content("<a>5</a>")
-						.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build());
+		assertThatExceptionOfType(FieldTypeRequiredException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one")))
+						.document(this.operationBuilder.request("http://localhost").content("<a>5</a>")
+								.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build()));
 	}
 
 	@Test
 	public void missingXmlRequestField() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Fields with the following paths were not found" + " in the payload: [a/b]"));
-		new RequestFieldsSnippet(
-				Arrays.asList(fieldWithPath("a/b").description("one"), fieldWithPath("a").description("one")))
-						.document(this.operationBuilder.request("http://localhost").content("<a></a>")
-								.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(
+						Arrays.asList(fieldWithPath("a/b").description("one"), fieldWithPath("a").description("one")))
+								.document(this.operationBuilder.request("http://localhost").content("<a></a>")
+										.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build()))
+				.withMessage("Fields with the following paths were not found in the payload: [a/b]");
 	}
 
 	@Test
 	public void undocumentedXmlRequestFieldAndMissingXmlRequestField() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(startsWith("The following parts of the payload were not documented:"));
-		this.thrown
-				.expectMessage(endsWith("Fields with the following paths were not found" + " in the payload: [a/b]"));
-		new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a/b").description("one")))
-				.document(this.operationBuilder.request("http://localhost").content("<a><c>5</c></a>")
-						.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a/b").description("one")))
+						.document(this.operationBuilder.request("http://localhost").content("<a><c>5</c></a>")
+								.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build()))
+				.withMessageStartingWith("The following parts of the payload were not documented:")
+				.withMessageEndingWith("Fields with the following paths were not found in the payload: [a/b]");
 	}
 
 	@Test
 	public void unsupportedContent() throws IOException {
-		this.thrown.expect(PayloadHandlingException.class);
-		this.thrown.expectMessage(
-				equalTo("Cannot handle text/plain content as it could" + " not be parsed as JSON or XML"));
-		new RequestFieldsSnippet(Collections.<FieldDescriptor>emptyList())
-				.document(this.operationBuilder.request("http://localhost").content("Some plain text")
-						.header(HttpHeaders.CONTENT_TYPE, MediaType.TEXT_PLAIN_VALUE).build());
+		assertThatExceptionOfType(PayloadHandlingException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(Collections.<FieldDescriptor>emptyList())
+						.document(this.operationBuilder.request("http://localhost").content("Some plain text")
+								.header(HttpHeaders.CONTENT_TYPE, MediaType.TEXT_PLAIN_VALUE).build()))
+				.withMessage("Cannot handle text/plain content as it could not be parsed as JSON or XML");
 	}
 
 	@Test
 	public void nonOptionalFieldBeneathArrayThatIsSometimesNull() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				startsWith("Fields with the following paths were not found in the payload: " + "[a[].b]"));
-		new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a[].b").description("one").type(JsonFieldType.NUMBER),
-				fieldWithPath("a[].c").description("two").type(JsonFieldType.NUMBER)))
-						.document(this.operationBuilder.request("http://localhost").content(
-								"{\"a\":[{\"b\": 1,\"c\": 2}, " + "{\"b\": null, \"c\": 2}," + " {\"b\": 1,\"c\": 2}]}")
-								.build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(
+						Arrays.asList(fieldWithPath("a[].b").description("one").type(JsonFieldType.NUMBER),
+								fieldWithPath("a[].c").description("two").type(JsonFieldType.NUMBER)))
+										.document(this.operationBuilder.request("http://localhost")
+												.content("{\"a\":[{\"b\": 1,\"c\": 2}, " + "{\"b\": null, \"c\": 2},"
+														+ " {\"b\": 1,\"c\": 2}]}")
+												.build()))
+				.withMessageStartingWith("Fields with the following paths were not found in the payload: [a[].b]");
 	}
 
 	@Test
 	public void nonOptionalFieldBeneathArrayThatIsSometimesAbsent() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				startsWith("Fields with the following paths were not found in the payload: " + "[a[].b]"));
-		new RequestFieldsSnippet(Arrays.asList(fieldWithPath("a[].b").description("one").type(JsonFieldType.NUMBER),
-				fieldWithPath("a[].c").description("two").type(JsonFieldType.NUMBER)))
-						.document(this.operationBuilder.request("http://localhost")
-								.content("{\"a\":[{\"b\": 1,\"c\": 2}, " + "{\"c\": 2}, {\"b\": 1,\"c\": 2}]}")
-								.build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestFieldsSnippet(
+						Arrays.asList(fieldWithPath("a[].b").description("one").type(JsonFieldType.NUMBER),
+								fieldWithPath("a[].c").description("two").type(JsonFieldType.NUMBER)))
+										.document(this.operationBuilder.request("http://localhost")
+												.content("{\"a\":[{\"b\": 1,\"c\": 2}, "
+														+ "{\"c\": 2}, {\"b\": 1,\"c\": 2}]}")
+												.build()))
+				.withMessageStartingWith("Fields with the following paths were not found in the payload: [a[].b]");
 	}
 
 }

spring-restdocs-core/src/test/java/org/springframework/restdocs/payload/RequestPartFieldsSnippetFailureTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,14 +22,12 @@ import java.util.Collections;
 
 import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 
 import org.springframework.restdocs.snippet.SnippetException;
 import org.springframework.restdocs.templates.TemplateFormats;
 import org.springframework.restdocs.testfixtures.OperationBuilder;
 
-import static org.hamcrest.CoreMatchers.equalTo;
-import static org.hamcrest.CoreMatchers.startsWith;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.springframework.restdocs.payload.PayloadDocumentation.fieldWithPath;
 
 /**
@@ -44,32 +42,32 @@ public class RequestPartFieldsSnippetFailureTests {
 	@Rule
 	public OperationBuilder operationBuilder = new OperationBuilder(TemplateFormats.asciidoctor());
 
-	@Rule
-	public ExpectedException thrown = ExpectedException.none();
-
 	@Test
 	public void undocumentedRequestPartField() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(startsWith("The following parts of the payload were not documented:"));
-		new RequestPartFieldsSnippet("part", Collections.<FieldDescriptor>emptyList()).document(
-				this.operationBuilder.request("http://localhost").part("part", "{\"a\": 5}".getBytes()).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestPartFieldsSnippet("part", Collections.<FieldDescriptor>emptyList())
+						.document(this.operationBuilder.request("http://localhost")
+								.part("part", "{\"a\": 5}".getBytes()).build()))
+				.withMessageStartingWith("The following parts of the payload were not documented:");
 	}
 
 	@Test
 	public void missingRequestPartField() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(startsWith("The following parts of the payload were not documented:"));
-		new RequestPartFieldsSnippet("part", Arrays.asList(fieldWithPath("b").description("one"))).document(
-				this.operationBuilder.request("http://localhost").part("part", "{\"a\": 5}".getBytes()).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(
+						() -> new RequestPartFieldsSnippet("part", Arrays.asList(fieldWithPath("b").description("one")))
+								.document(this.operationBuilder.request("http://localhost")
+										.part("part", "{\"a\": 5}".getBytes()).build()))
+				.withMessageStartingWith("The following parts of the payload were not documented:");
 	}
 
 	@Test
 	public void missingRequestPart() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("A request part named 'another' was not found in the request"));
-		new RequestPartFieldsSnippet("another", Arrays.asList(fieldWithPath("a.b").description("one")))
-				.document(this.operationBuilder.request("http://localhost")
-						.part("part", "{\"a\": {\"b\": 5}}".getBytes()).build());
+		assertThatExceptionOfType(SnippetException.class).isThrownBy(
+				() -> new RequestPartFieldsSnippet("another", Arrays.asList(fieldWithPath("a.b").description("one")))
+						.document(this.operationBuilder.request("http://localhost")
+								.part("part", "{\"a\": {\"b\": 5}}".getBytes()).build()))
+				.withMessage("A request part named 'another' was not found in the request");
 	}
 
 }

spring-restdocs-core/src/test/java/org/springframework/restdocs/payload/ResponseFieldsSnippetFailureTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,7 +22,6 @@ import java.util.Collections;
 
 import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
@@ -30,9 +29,7 @@ import org.springframework.restdocs.snippet.SnippetException;
 import org.springframework.restdocs.templates.TemplateFormats;
 import org.springframework.restdocs.testfixtures.OperationBuilder;
 
-import static org.hamcrest.CoreMatchers.endsWith;
-import static org.hamcrest.CoreMatchers.equalTo;
-import static org.hamcrest.CoreMatchers.startsWith;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.springframework.restdocs.payload.PayloadDocumentation.fieldWithPath;
 
 /**
@@ -46,124 +43,125 @@ public class ResponseFieldsSnippetFailureTests {
 	@Rule
 	public OperationBuilder operationBuilder = new OperationBuilder(TemplateFormats.asciidoctor());
 
-	@Rule
-	public ExpectedException thrown = ExpectedException.none();
-
 	@Test
 	public void attemptToDocumentFieldsWithNoResponseBody() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Cannot document response fields as the response body is empty"));
-		new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one")))
-				.document(this.operationBuilder.build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one")))
+						.document(this.operationBuilder.build()))
+				.withMessage("Cannot document response fields as the response body is empty");
 	}
 
 	@Test
 	public void fieldWithExplicitTypeThatDoesNotMatchThePayload() throws IOException {
-		this.thrown.expect(FieldTypesDoNotMatchException.class);
-		this.thrown.expectMessage(
-				equalTo("The documented type of the field 'a' is" + " Object but the actual type is Number"));
-		new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one").type(JsonFieldType.OBJECT)))
-				.document(this.operationBuilder.response().content("{ \"a\": 5 }}").build());
+		assertThatExceptionOfType(FieldTypesDoNotMatchException.class)
+				.isThrownBy(() -> new ResponseFieldsSnippet(
+						Arrays.asList(fieldWithPath("a").description("one").type(JsonFieldType.OBJECT)))
+								.document(this.operationBuilder.response().content("{ \"a\": 5 }}").build()))
+				.withMessage("The documented type of the field 'a' is Object but the actual type is Number");
 	}
 
 	@Test
 	public void fieldWithExplicitSpecificTypeThatActuallyVaries() throws IOException {
-		this.thrown.expect(FieldTypesDoNotMatchException.class);
-		this.thrown.expectMessage(
-				equalTo("The documented type of the field '[].a' is" + " Object but the actual type is Varies"));
-		new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("[].a").description("one").type(JsonFieldType.OBJECT)))
-				.document(this.operationBuilder.response().content("[{ \"a\": 5 },{ \"a\": \"b\" }]").build());
+		assertThatExceptionOfType(FieldTypesDoNotMatchException.class)
+				.isThrownBy(() -> new ResponseFieldsSnippet(
+						Arrays.asList(fieldWithPath("[].a").description("one").type(JsonFieldType.OBJECT))).document(
+								this.operationBuilder.response().content("[{ \"a\": 5 },{ \"a\": \"b\" }]").build()))
+				.withMessage("The documented type of the field '[].a' is Object but the actual type is Varies");
 	}
 
 	@Test
 	public void undocumentedXmlResponseField() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(startsWith("The following parts of the payload were not" + " documented:"));
-		new ResponseFieldsSnippet(Collections.<FieldDescriptor>emptyList()).document(this.operationBuilder.response()
-				.content("<a><b>5</b></a>").header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new ResponseFieldsSnippet(Collections.<FieldDescriptor>emptyList())
+						.document(this.operationBuilder.response().content("<a><b>5</b></a>")
+								.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build()))
+				.withMessageStartingWith("The following parts of the payload were not documented:");
 	}
 
 	@Test
 	public void missingXmlAttribute() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown
-				.expectMessage(equalTo("Fields with the following paths were not found" + " in the payload: [a/@id]"));
-		new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one").type("b"),
-				fieldWithPath("a/@id").description("two").type("c")))
-						.document(this.operationBuilder.response().content("<a>foo</a>")
-								.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(
+						() -> new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one").type("b"),
+								fieldWithPath("a/@id").description("two").type("c")))
+										.document(
+												this.operationBuilder.response().content("<a>foo</a>")
+														.header(HttpHeaders.CONTENT_TYPE,
+																MediaType.APPLICATION_XML_VALUE)
+														.build()))
+				.withMessage("Fields with the following paths were not found in the payload: [a/@id]");
 	}
 
 	@Test
 	public void documentedXmlAttributesAreRemoved() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				equalTo(String.format("The following parts of the payload were not documented:" + "%n<a>bar</a>%n")));
-		new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a/@id").description("one").type("a")))
-				.document(this.operationBuilder.response().content("<a id=\"foo\">bar</a>")
-						.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build());
+		assertThatExceptionOfType(SnippetException.class).isThrownBy(
+				() -> new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a/@id").description("one").type("a")))
+						.document(this.operationBuilder.response().content("<a id=\"foo\">bar</a>")
+								.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build()))
+				.withMessage(String.format("The following parts of the payload were not documented:%n<a>bar</a>%n"));
 	}
 
 	@Test
 	public void xmlResponseFieldWithNoType() throws IOException {
-		this.thrown.expect(FieldTypeRequiredException.class);
-		new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one")))
-				.document(this.operationBuilder.response().content("<a>5</a>")
-						.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build());
+		assertThatExceptionOfType(FieldTypeRequiredException.class)
+				.isThrownBy(() -> new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a").description("one")))
+						.document(this.operationBuilder.response().content("<a>5</a>")
+								.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build()));
 	}
 
 	@Test
 	public void missingXmlResponseField() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Fields with the following paths were not found" + " in the payload: [a/b]"));
-		new ResponseFieldsSnippet(
-				Arrays.asList(fieldWithPath("a/b").description("one"), fieldWithPath("a").description("one")))
-						.document(this.operationBuilder.response().content("<a></a>")
-								.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new ResponseFieldsSnippet(
+						Arrays.asList(fieldWithPath("a/b").description("one"), fieldWithPath("a").description("one")))
+								.document(this.operationBuilder.response().content("<a></a>")
+										.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build()))
+				.withMessage("Fields with the following paths were not found in the payload: [a/b]");
 	}
 
 	@Test
 	public void undocumentedXmlResponseFieldAndMissingXmlResponseField() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(startsWith("The following parts of the payload were not" + " documented:"));
-		this.thrown
-				.expectMessage(endsWith("Fields with the following paths were not found" + " in the payload: [a/b]"));
-		new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a/b").description("one")))
-				.document(this.operationBuilder.response().content("<a><c>5</c></a>")
-						.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a/b").description("one")))
+						.document(this.operationBuilder.response().content("<a><c>5</c></a>")
+								.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_XML_VALUE).build()))
+				.withMessageStartingWith("The following parts of the payload were not documented:")
+				.withMessageEndingWith("Fields with the following paths were not found in the payload: [a/b]");
 	}
 
 	@Test
 	public void unsupportedContent() throws IOException {
-		this.thrown.expect(PayloadHandlingException.class);
-		this.thrown.expectMessage(
-				equalTo("Cannot handle text/plain content as it could" + " not be parsed as JSON or XML"));
-		new ResponseFieldsSnippet(Collections.<FieldDescriptor>emptyList()).document(this.operationBuilder.response()
-				.content("Some plain text").header(HttpHeaders.CONTENT_TYPE, MediaType.TEXT_PLAIN_VALUE).build());
+		assertThatExceptionOfType(PayloadHandlingException.class)
+				.isThrownBy(() -> new ResponseFieldsSnippet(Collections.<FieldDescriptor>emptyList())
+						.document(this.operationBuilder.response().content("Some plain text")
+								.header(HttpHeaders.CONTENT_TYPE, MediaType.TEXT_PLAIN_VALUE).build()))
+				.withMessage("Cannot handle text/plain content as it could not be parsed as JSON or XML");
 	}
 
 	@Test
 	public void nonOptionalFieldBeneathArrayThatIsSometimesNull() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				startsWith("Fields with the following paths were not found in the payload: " + "[a[].b]"));
-		new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a[].b").description("one").type(JsonFieldType.NUMBER),
-				fieldWithPath("a[].c").description("two").type(JsonFieldType.NUMBER)))
-						.document(this.operationBuilder.response().content(
-								"{\"a\":[{\"b\": 1,\"c\": 2}, " + "{\"b\": null, \"c\": 2}," + " {\"b\": 1,\"c\": 2}]}")
-								.build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new ResponseFieldsSnippet(
+						Arrays.asList(fieldWithPath("a[].b").description("one").type(JsonFieldType.NUMBER),
+								fieldWithPath("a[].c").description("two").type(JsonFieldType.NUMBER)))
+										.document(this.operationBuilder.response()
+												.content("{\"a\":[{\"b\": 1,\"c\": 2}, " + "{\"b\": null, \"c\": 2},"
+														+ " {\"b\": 1,\"c\": 2}]}")
+												.build()))
+				.withMessageStartingWith("Fields with the following paths were not found in the payload: [a[].b]");
 	}
 
 	@Test
 	public void nonOptionalFieldBeneathArrayThatIsSometimesAbsent() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				startsWith("Fields with the following paths were not found in the payload: " + "[a[].b]"));
-		new ResponseFieldsSnippet(Arrays.asList(fieldWithPath("a[].b").description("one").type(JsonFieldType.NUMBER),
-				fieldWithPath("a[].c").description("two").type(JsonFieldType.NUMBER)))
-						.document(this.operationBuilder.response()
-								.content("{\"a\":[{\"b\": 1,\"c\": 2}, " + "{\"c\": 2}, {\"b\": 1,\"c\": 2}]}")
-								.build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new ResponseFieldsSnippet(
+						Arrays.asList(fieldWithPath("a[].b").description("one").type(JsonFieldType.NUMBER),
+								fieldWithPath("a[].c").description("two").type(JsonFieldType.NUMBER)))
+										.document(this.operationBuilder.response()
+												.content("{\"a\":[{\"b\": 1,\"c\": 2}, "
+														+ "{\"c\": 2}, {\"b\": 1,\"c\": 2}]}")
+												.build()))
+				.withMessageStartingWith("Fields with the following paths were not found in the payload: [a[].b]");
 	}
 
 }

spring-restdocs-core/src/test/java/org/springframework/restdocs/request/PathParametersSnippetFailureTests.java

@@ -22,14 +22,13 @@ import java.util.Collections;
 
 import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 
 import org.springframework.restdocs.generate.RestDocumentationGenerator;
 import org.springframework.restdocs.snippet.SnippetException;
 import org.springframework.restdocs.templates.TemplateFormats;
 import org.springframework.restdocs.testfixtures.OperationBuilder;
 
-import static org.hamcrest.CoreMatchers.equalTo;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.springframework.restdocs.request.RequestDocumentation.parameterWithName;
 
 /**
@@ -43,35 +42,33 @@ public class PathParametersSnippetFailureTests {
 	@Rule
 	public OperationBuilder operationBuilder = new OperationBuilder(TemplateFormats.asciidoctor());
 
-	@Rule
-	public ExpectedException thrown = ExpectedException.none();
-
 	@Test
 	public void undocumentedPathParameter() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Path parameters with the following names were" + " not documented: [a]"));
-		new PathParametersSnippet(Collections.<ParameterDescriptor>emptyList()).document(this.operationBuilder
-				.attribute(RestDocumentationGenerator.ATTRIBUTE_NAME_URL_TEMPLATE, "/{a}/").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new PathParametersSnippet(Collections.<ParameterDescriptor>emptyList())
+						.document(this.operationBuilder
+								.attribute(RestDocumentationGenerator.ATTRIBUTE_NAME_URL_TEMPLATE, "/{a}/").build()))
+				.withMessage("Path parameters with the following names were not documented: [a]");
 	}
 
 	@Test
 	public void missingPathParameter() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				equalTo("Path parameters with the following names were" + " not found in the request: [a]"));
-		new PathParametersSnippet(Arrays.asList(parameterWithName("a").description("one"))).document(
-				this.operationBuilder.attribute(RestDocumentationGenerator.ATTRIBUTE_NAME_URL_TEMPLATE, "/").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new PathParametersSnippet(Arrays.asList(parameterWithName("a").description("one")))
+						.document(this.operationBuilder
+								.attribute(RestDocumentationGenerator.ATTRIBUTE_NAME_URL_TEMPLATE, "/").build()))
+				.withMessage("Path parameters with the following names were not found in the request: [a]");
 	}
 
 	@Test
 	public void undocumentedAndMissingPathParameters() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Path parameters with the following names were"
-				+ " not documented: [b]. Path parameters with the following"
-				+ " names were not found in the request: [a]"));
-		new PathParametersSnippet(Arrays.asList(parameterWithName("a").description("one")))
-				.document(this.operationBuilder
-						.attribute(RestDocumentationGenerator.ATTRIBUTE_NAME_URL_TEMPLATE, "/{b}").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new PathParametersSnippet(Arrays.asList(parameterWithName("a").description("one")))
+						.document(this.operationBuilder
+								.attribute(RestDocumentationGenerator.ATTRIBUTE_NAME_URL_TEMPLATE, "/{b}").build()))
+				.withMessage(
+						"Path parameters with the following names were not documented: [b]. Path parameters with the"
+								+ " following names were not found in the request: [a]");
 	}
 
 }

spring-restdocs-core/src/test/java/org/springframework/restdocs/request/RequestParametersSnippetFailureTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,13 +22,12 @@ import java.util.Collections;
 
 import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 
 import org.springframework.restdocs.snippet.SnippetException;
 import org.springframework.restdocs.templates.TemplateFormats;
 import org.springframework.restdocs.testfixtures.OperationBuilder;
 
-import static org.hamcrest.CoreMatchers.equalTo;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.springframework.restdocs.request.RequestDocumentation.parameterWithName;
 
 /**
@@ -42,34 +41,29 @@ public class RequestParametersSnippetFailureTests {
 	@Rule
 	public OperationBuilder operationBuilder = new OperationBuilder(TemplateFormats.asciidoctor());
 
-	@Rule
-	public ExpectedException thrown = ExpectedException.none();
-
 	@Test
 	public void undocumentedParameter() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Request parameters with the following names were" + " not documented: [a]"));
-		new RequestParametersSnippet(Collections.<ParameterDescriptor>emptyList())
-				.document(this.operationBuilder.request("http://localhost").param("a", "alpha").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestParametersSnippet(Collections.<ParameterDescriptor>emptyList())
+						.document(this.operationBuilder.request("http://localhost").param("a", "alpha").build()))
+				.withMessage("Request parameters with the following names were not documented: [a]");
 	}
 
 	@Test
 	public void missingParameter() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				equalTo("Request parameters with the following names were" + " not found in the request: [a]"));
-		new RequestParametersSnippet(Arrays.asList(parameterWithName("a").description("one")))
-				.document(this.operationBuilder.request("http://localhost").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestParametersSnippet(Arrays.asList(parameterWithName("a").description("one")))
+						.document(this.operationBuilder.request("http://localhost").build()))
+				.withMessage("Request parameters with the following names were not found in the request: [a]");
 	}
 
 	@Test
 	public void undocumentedAndMissingParameters() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Request parameters with the following names were"
-				+ " not documented: [b]. Request parameters with the following"
-				+ " names were not found in the request: [a]"));
-		new RequestParametersSnippet(Arrays.asList(parameterWithName("a").description("one")))
-				.document(this.operationBuilder.request("http://localhost").param("b", "bravo").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestParametersSnippet(Arrays.asList(parameterWithName("a").description("one")))
+						.document(this.operationBuilder.request("http://localhost").param("b", "bravo").build()))
+				.withMessage("Request parameters with the following names were not documented: [b]. Request parameters"
+						+ " with the following names were not found in the request: [a]");
 	}
 
 }

spring-restdocs-core/src/test/java/org/springframework/restdocs/request/RequestPartsSnippetFailureTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,13 +22,12 @@ import java.util.Collections;
 
 import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 
 import org.springframework.restdocs.snippet.SnippetException;
 import org.springframework.restdocs.templates.TemplateFormats;
 import org.springframework.restdocs.testfixtures.OperationBuilder;
 
-import static org.hamcrest.CoreMatchers.equalTo;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.springframework.restdocs.request.RequestDocumentation.partWithName;
 
 /**
@@ -42,34 +41,29 @@ public class RequestPartsSnippetFailureTests {
 	@Rule
 	public OperationBuilder operationBuilder = new OperationBuilder(TemplateFormats.asciidoctor());
 
-	@Rule
-	public ExpectedException thrown = ExpectedException.none();
-
 	@Test
 	public void undocumentedPart() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo("Request parts with the following names were" + " not documented: [a]"));
-		new RequestPartsSnippet(Collections.<RequestPartDescriptor>emptyList())
-				.document(this.operationBuilder.request("http://localhost").part("a", "alpha".getBytes()).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestPartsSnippet(Collections.<RequestPartDescriptor>emptyList()).document(
+						this.operationBuilder.request("http://localhost").part("a", "alpha".getBytes()).build()))
+				.withMessage("Request parts with the following names were not documented: [a]");
 	}
 
 	@Test
 	public void missingPart() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(
-				equalTo("Request parts with the following names were" + " not found in the request: [a]"));
-		new RequestPartsSnippet(Arrays.asList(partWithName("a").description("one")))
-				.document(this.operationBuilder.request("http://localhost").build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestPartsSnippet(Arrays.asList(partWithName("a").description("one")))
+						.document(this.operationBuilder.request("http://localhost").build()))
+				.withMessage("Request parts with the following names were not found in the request: [a]");
 	}
 
 	@Test
 	public void undocumentedAndMissingParts() throws IOException {
-		this.thrown.expect(SnippetException.class);
-		this.thrown.expectMessage(equalTo(
-				"Request parts with the following names were" + " not documented: [b]. Request parts with the following"
-						+ " names were not found in the request: [a]"));
-		new RequestPartsSnippet(Arrays.asList(partWithName("a").description("one")))
-				.document(this.operationBuilder.request("http://localhost").part("b", "bravo".getBytes()).build());
+		assertThatExceptionOfType(SnippetException.class)
+				.isThrownBy(() -> new RequestPartsSnippet(Arrays.asList(partWithName("a").description("one"))).document(
+						this.operationBuilder.request("http://localhost").part("b", "bravo".getBytes()).build()))
+				.withMessage("Request parts with the following names were not documented: [b]. Request parts with the"
+						+ " following names were not found in the request: [a]");
 	}
 
 }

spring-restdocs-core/src/test/java/org/springframework/restdocs/templates/StandardTemplateResourceResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,14 +21,12 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.Callable;
 
-import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 
 import org.springframework.core.io.Resource;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.hamcrest.CoreMatchers.equalTo;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 
 /**
  * Tests for {@link TemplateResourceResolver}.
@@ -37,9 +35,6 @@ import static org.hamcrest.CoreMatchers.equalTo;
  */
 public class StandardTemplateResourceResolverTests {
 
-	@Rule
-	public final ExpectedException thrown = ExpectedException.none();
-
 	private final TemplateResourceResolver resolver = new StandardTemplateResourceResolver(
 			TemplateFormats.asciidoctor());
 
@@ -101,16 +96,10 @@ public class StandardTemplateResourceResolverTests {
 
 	@Test
 	public void failsIfCustomAndDefaultSnippetsDoNotExist() throws Exception {
-		this.thrown.expect(IllegalStateException.class);
-		this.thrown.expectMessage(equalTo("Template named 'test' could not be resolved"));
-		doWithThreadContextClassLoader(this.classLoader, new Callable<Resource>() {
-
-			@Override
-			public Resource call() {
-				return StandardTemplateResourceResolverTests.this.resolver.resolveTemplateResource("test");
-			}
-
-		});
+		assertThatIllegalStateException()
+				.isThrownBy(() -> doWithThreadContextClassLoader(this.classLoader,
+						() -> StandardTemplateResourceResolverTests.this.resolver.resolveTemplateResource("test")))
+				.withMessage("Template named 'test' could not be resolved");
 	}
 
 	private <T> T doWithThreadContextClassLoader(ClassLoader classLoader, Callable<T> action) throws Exception {

spring-restdocs-core/src/testFixtures/java/org/springframework/restdocs/testfixtures/CapturedOutput.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2014-2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.restdocs.testfixtures;
+
+/**
+ * Provides access to {@link System#out System.out} and {@link System#err System.err}
+ * output that has been captured by the {@link OutputCaptureRule}. Can be used to apply
+ * assertions using AssertJ. For example: <pre class="code">
+ * assertThat(output).contains("started"); // Checks all output
+ * assertThat(output.getErr()).contains("failed"); // Only checks System.err
+ * assertThat(output.getOut()).contains("ok"); // Only checks System.out
+ * </pre>
+ *
+ * @author Madhura Bhave
+ * @author Phillip Webb
+ * @author Andy Wilkinson
+ */
+public interface CapturedOutput extends CharSequence {
+
+	@Override
+	default int length() {
+		return toString().length();
+	}
+
+	@Override
+	default char charAt(int index) {
+		return toString().charAt(index);
+	}
+
+	@Override
+	default CharSequence subSequence(int start, int end) {
+		return toString().subSequence(start, end);
+	}
+
+	/**
+	 * Return all content (both {@link System#out System.out} and {@link System#err
+	 * System.err}) in the order that it was captured.
+	 * @return all captured output
+	 */
+	String getAll();
+
+	/**
+	 * Return {@link System#out System.out} content in the order that it was captured.
+	 * @return {@link System#out System.out} captured output
+	 */
+	String getOut();
+
+	/**
+	 * Return {@link System#err System.err} content in the order that it was captured.
+	 * @return {@link System#err System.err} captured output
+	 */
+	String getErr();
+
+}

spring-restdocs-core/src/testFixtures/java/org/springframework/restdocs/testfixtures/OutputCapture.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2014-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,139 +16,257 @@
 
 package org.springframework.restdocs.testfixtures;
 
-import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.PrintStream;
+import java.util.ArrayDeque;
 import java.util.ArrayList;
+import java.util.Deque;
 import java.util.List;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
 
-import org.assertj.core.api.HamcrestCondition;
-import org.hamcrest.Matcher;
-import org.junit.rules.TestRule;
-import org.junit.runner.Description;
-import org.junit.runners.model.Statement;
-
-import static org.assertj.core.api.Assertions.assertThat;
-import static org.hamcrest.Matchers.allOf;
+import org.springframework.util.Assert;
 
 /**
- * JUnit {@code @Rule} to capture output from System.out and System.err.
+ * Provides support for capturing {@link System#out System.out} and {@link System#err
+ * System.err}.
  *
+ * @author Madhura Bhave
  * @author Phillip Webb
  * @author Andy Wilkinson
+ * @author Sam Brannen
+ * @see OutputCaptureRule
  */
-public class OutputCapture implements TestRule {
+class OutputCapture implements CapturedOutput {
 
-	private CaptureOutputStream captureOut;
+	private final Deque<SystemCapture> systemCaptures = new ArrayDeque<>();
 
-	private CaptureOutputStream captureErr;
-
-	private ByteArrayOutputStream capturedOutput;
-
-	private List<Matcher<? super String>> matchers = new ArrayList<>();
-
-	@Override
-	public Statement apply(final Statement base, Description description) {
-		return new Statement() {
-			@Override
-			public void evaluate() throws Throwable {
-				captureOutput();
-				try {
-					base.evaluate();
-				}
-				finally {
-					try {
-						if (!OutputCapture.this.matchers.isEmpty()) {
-							assertThat(getOutputAsString())
-									.is(new HamcrestCondition<>(allOf(OutputCapture.this.matchers)));
-						}
-					}
-					finally {
-						releaseOutput();
-					}
-				}
-			}
-		};
-	}
-
-	private void captureOutput() {
-		this.capturedOutput = new ByteArrayOutputStream();
-		this.captureOut = new CaptureOutputStream(System.out, this.capturedOutput);
-		this.captureErr = new CaptureOutputStream(System.err, this.capturedOutput);
-		System.setOut(new PrintStream(this.captureOut));
-		System.setErr(new PrintStream(this.captureErr));
-	}
-
-	private String getOutputAsString() {
-		flush();
-		return this.capturedOutput.toString();
-	}
-
-	private void releaseOutput() {
-		System.setOut(this.captureOut.getOriginal());
-		System.setErr(this.captureErr.getOriginal());
-		this.capturedOutput = null;
-	}
-
-	private void flush() {
-		try {
-			this.captureOut.flush();
-			this.captureErr.flush();
-		}
-		catch (IOException ex) {
-			// ignore
-		}
+	/**
+	 * Push a new system capture session onto the stack.
+	 */
+	final void push() {
+		this.systemCaptures.addLast(new SystemCapture());
 	}
 
 	/**
-	 * Verify that the output is matched by the supplied {@code matcher}. Verification is
-	 * performed after the test method has executed.
-	 * @param matcher the matcher
+	 * Pop the last system capture session from the stack.
 	 */
-	public final void expect(Matcher<? super String> matcher) {
-		this.matchers.add(matcher);
+	final void pop() {
+		this.systemCaptures.removeLast().release();
 	}
 
-	private static final class CaptureOutputStream extends OutputStream {
+	@Override
+	public boolean equals(Object obj) {
+		if (obj == this) {
+			return true;
+		}
+		if (obj instanceof CapturedOutput || obj instanceof CharSequence) {
+			return getAll().equals(obj.toString());
+		}
+		return false;
+	}
 
-		private final PrintStream original;
+	@Override
+	public int hashCode() {
+		return toString().hashCode();
+	}
 
-		private final OutputStream copy;
+	@Override
+	public String toString() {
+		return getAll();
+	}
 
-		private CaptureOutputStream(PrintStream original, OutputStream copy) {
-			this.original = original;
+	/**
+	 * Return all content (both {@link System#out System.out} and {@link System#err
+	 * System.err}) in the order that it was captured.
+	 * @return all captured output
+	 */
+	@Override
+	public String getAll() {
+		return get((type) -> true);
+	}
+
+	/**
+	 * Return {@link System#out System.out} content in the order that it was captured.
+	 * @return {@link System#out System.out} captured output
+	 */
+	@Override
+	public String getOut() {
+		return get(Type.OUT::equals);
+	}
+
+	/**
+	 * Return {@link System#err System.err} content in the order that it was captured.
+	 * @return {@link System#err System.err} captured output
+	 */
+	@Override
+	public String getErr() {
+		return get(Type.ERR::equals);
+	}
+
+	/**
+	 * Resets the current capture session, clearing its captured output.
+	 */
+	void reset() {
+		this.systemCaptures.peek().reset();
+	}
+
+	private String get(Predicate<Type> filter) {
+		Assert.state(!this.systemCaptures.isEmpty(),
+				"No system captures found. Please check your output capture registration.");
+		StringBuilder builder = new StringBuilder();
+		for (SystemCapture systemCapture : this.systemCaptures) {
+			systemCapture.append(builder, filter);
+		}
+		return builder.toString();
+	}
+
+	/**
+	 * A capture session that captures {@link System#out System.out} and {@link System#out
+	 * System.err}.
+	 */
+	private static class SystemCapture {
+
+		private final Object monitor = new Object();
+
+		private final PrintStreamCapture out;
+
+		private final PrintStreamCapture err;
+
+		private final List<CapturedString> capturedStrings = new ArrayList<>();
+
+		SystemCapture() {
+			this.out = new PrintStreamCapture(System.out, this::captureOut);
+			this.err = new PrintStreamCapture(System.err, this::captureErr);
+			System.setOut(this.out);
+			System.setErr(this.err);
+		}
+
+		void release() {
+			System.setOut(this.out.getParent());
+			System.setErr(this.err.getParent());
+		}
+
+		private void captureOut(String string) {
+			synchronized (this.monitor) {
+				this.capturedStrings.add(new CapturedString(Type.OUT, string));
+			}
+		}
+
+		private void captureErr(String string) {
+			synchronized (this.monitor) {
+				this.capturedStrings.add(new CapturedString(Type.ERR, string));
+			}
+		}
+
+		void append(StringBuilder builder, Predicate<Type> filter) {
+			synchronized (this.monitor) {
+				for (CapturedString stringCapture : this.capturedStrings) {
+					if (filter.test(stringCapture.getType())) {
+						builder.append(stringCapture);
+					}
+				}
+			}
+		}
+
+		void reset() {
+			synchronized (this.monitor) {
+				this.capturedStrings.clear();
+			}
+		}
+
+	}
+
+	/**
+	 * A {@link PrintStream} implementation that captures written strings.
+	 */
+	private static class PrintStreamCapture extends PrintStream {
+
+		private final PrintStream parent;
+
+		PrintStreamCapture(PrintStream parent, Consumer<String> copy) {
+			super(new OutputStreamCapture(getSystemStream(parent), copy));
+			this.parent = parent;
+		}
+
+		PrintStream getParent() {
+			return this.parent;
+		}
+
+		private static PrintStream getSystemStream(PrintStream printStream) {
+			while (printStream instanceof PrintStreamCapture) {
+				printStream = ((PrintStreamCapture) printStream).getParent();
+			}
+			return printStream;
+		}
+
+	}
+
+	/**
+	 * An {@link OutputStream} implementation that captures written strings.
+	 */
+	private static class OutputStreamCapture extends OutputStream {
+
+		private final PrintStream systemStream;
+
+		private final Consumer<String> copy;
+
+		OutputStreamCapture(PrintStream systemStream, Consumer<String> copy) {
+			this.systemStream = systemStream;
 			this.copy = copy;
 		}
 
 		@Override
 		public void write(int b) throws IOException {
-			this.copy.write(b);
-			this.original.write(b);
-			this.original.flush();
-		}
-
-		@Override
-		public void write(byte[] b) throws IOException {
-			write(b, 0, b.length);
+			write(new byte[] { (byte) (b & 0xFF) });
 		}
 
 		@Override
 		public void write(byte[] b, int off, int len) throws IOException {
-			this.copy.write(b, off, len);
-			this.original.write(b, off, len);
-		}
-
-		private PrintStream getOriginal() {
-			return this.original;
+			this.copy.accept(new String(b, off, len));
+			this.systemStream.write(b, off, len);
 		}
 
 		@Override
 		public void flush() throws IOException {
-			this.copy.flush();
-			this.original.flush();
+			this.systemStream.flush();
 		}
 
 	}
 
+	/**
+	 * A captured string that forms part of the full output.
+	 */
+	private static class CapturedString {
+
+		private final Type type;
+
+		private final String string;
+
+		CapturedString(Type type, String string) {
+			this.type = type;
+			this.string = string;
+		}
+
+		Type getType() {
+			return this.type;
+		}
+
+		@Override
+		public String toString() {
+			return this.string;
+		}
+
+	}
+
+	/**
+	 * Types of content that can be captured.
+	 */
+	private enum Type {
+
+		OUT, ERR
+
+	}
+
 }

spring-restdocs-core/src/testFixtures/java/org/springframework/restdocs/testfixtures/OutputCaptureRule.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2014-2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.restdocs.testfixtures;
+
+import org.junit.Rule;
+import org.junit.rules.TestRule;
+import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
+
+/**
+ * JUnit {@code @Rule} to capture output from System.out and System.err.
+ * <p>
+ * To use add as a {@link Rule @Rule}:
+ *
+ * <pre class="code">
+ * public class MyTest {
+ *
+ *     &#064;Rule
+ *     public OutputCaptureRule output = new OutputCaptureRule();
+ *
+ *     &#064;Test
+ *     public void test() {
+ *         assertThat(output).contains("ok");
+ *     }
+ *
+ * }
+ * </pre>
+ *
+ * @author Phillip Webb
+ * @author Andy Wilkinson
+ */
+public class OutputCaptureRule implements TestRule, CapturedOutput {
+
+	private final OutputCapture delegate = new OutputCapture();
+
+	@Override
+	public Statement apply(Statement base, Description description) {
+		return new Statement() {
+			@Override
+			public void evaluate() throws Throwable {
+				OutputCaptureRule.this.delegate.push();
+				try {
+					base.evaluate();
+				}
+				finally {
+					OutputCaptureRule.this.delegate.pop();
+				}
+			}
+		};
+	}
+
+	@Override
+	public String getAll() {
+		return this.delegate.getAll();
+	}
+
+	@Override
+	public String getOut() {
+		return this.delegate.getOut();
+	}
+
+	@Override
+	public String getErr() {
+		return this.delegate.getErr();
+	}
+
+	@Override
+	public String toString() {
+		return this.delegate.toString();
+	}
+
+}