StubRunnerExtension can't be registered around non static field

fixes gh-1458

spring-cloud-contract-stub-runner/src/main/java/org/springframework/cloud/contract/stubrunner/junit/StubRunnerExtension.java

@@ -26,7 +26,9 @@ import java.util.Map;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.junit.jupiter.api.extension.AfterAllCallback;
+import org.junit.jupiter.api.extension.AfterEachCallback;
 import org.junit.jupiter.api.extension.BeforeAllCallback;
+import org.junit.jupiter.api.extension.BeforeEachCallback;
 import org.junit.jupiter.api.extension.ExtensionContext;
 
 import org.springframework.cloud.contract.spec.Contract;
@@ -48,7 +50,7 @@ import org.springframework.cloud.contract.verifier.messaging.MessageVerifier;
  * @author Olga Maciaszek-Sharma
  * @since 2.1.0
  */
-public class StubRunnerExtension implements BeforeAllCallback, AfterAllCallback,
+public class StubRunnerExtension implements BeforeAllCallback, AfterAllCallback, BeforeEachCallback, AfterEachCallback,
 		StubFinder, StubRunnerExtensionOptions {
 
 	private static final String DELIMITER = ":";
@@ -73,15 +75,33 @@ public class StubRunnerExtension implements BeforeAllCallback, AfterAllCallback,
 		this.delegate = delegate;
 	}
 
+	@Override
+	public void afterAll(ExtensionContext extensionContext) {
+		after();
+	}
+
+	@Override
+	public void afterEach(ExtensionContext context) throws Exception {
+		after();
+	}
+
 	@Override
 	public void beforeAll(ExtensionContext extensionContext) {
+		before();
+	}
+
+	@Override
+	public void beforeEach(ExtensionContext context) throws Exception {
+		before();
+	}
+
+	private void before() {
 		stubFinder(new BatchStubRunnerFactory(builder().build(), verifier())
 				.buildBatchStubRunner());
 		stubFinder().runStubs();
 	}
 
-	@Override
-	public void afterAll(ExtensionContext extensionContext) {
+	private void after() {
 		try {
 			stubFinder().close();
 		}
@@ -90,6 +110,7 @@ public class StubRunnerExtension implements BeforeAllCallback, AfterAllCallback,
 		}
 	}
 
+
 	@Override
 	public URL findStubUrl(String groupId, String artifactId)
 			throws StubNotFoundException {

spring-cloud-contract-stub-runner/src/main/java/org/springframework/cloud/contract/stubrunner/junit/StubRunnerRule.java

@@ -199,7 +199,7 @@ public class StubRunnerRule implements TestRule, StubFinder, StubRunnerRuleOptio
 	@Override
 	public StubRunnerRule failOnNoStubs(boolean failOnNoStubs) {
 		builder().withFailOnNoStubs(failOnNoStubs);
-		return null;
+		return this.delegate;
 	}
 
 	@Override

spring-cloud-contract-stub-runner/src/test/java/org/springframework/cloud/contract/stubrunner/junit/StubRunnerJUnit5MethodExtensionTests.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright 2018-2020 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.cloud.contract.stubrunner.junit;
+
+import java.io.File;
+import java.net.URL;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import org.springframework.cloud.contract.stubrunner.spring.StubRunnerProperties;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Olga Maciaszek-Sharma
+ * @since 2.1.0
+ */
+class StubRunnerJUnit5MethodExtensionTests {
+
+	// tag::extension[]
+	// Visible for Junit
+	@RegisterExtension
+	StubRunnerExtension stubRunnerExtension = new StubRunnerExtension()
+			.repoRoot(repoRoot()).stubsMode(StubRunnerProperties.StubsMode.REMOTE)
+			.downloadStub("org.springframework.cloud.contract.verifier.stubs",
+					"loanIssuance")
+			.downloadStub(
+					"org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")
+			.withMappingsOutputFolder("target/outputmappingsforrule");
+
+	@BeforeEach
+	@AfterEach
+	void setupProps() {
+		System.clearProperty("stubrunner.repository.root");
+		System.clearProperty("stubrunner.classifier");
+	}
+
+	private static String repoRoot() {
+		try {
+			return StubRunnerRuleJUnitTest.class.getResource("/m2repo/repository/")
+					.toURI().toString();
+		}
+		catch (Exception e) {
+			return "";
+		}
+	}
+	// end::extension[]
+
+	@Test
+	void should_start_WireMock_servers() {
+		assertThat(stubRunnerExtension.findStubUrl(
+				"org.springframework.cloud.contract.verifier.stubs", "loanIssuance"))
+						.isNotNull();
+		assertThat(stubRunnerExtension.findStubUrl("loanIssuance")).isNotNull();
+		assertThat(stubRunnerExtension.findStubUrl("loanIssuance"))
+				.isEqualTo(stubRunnerExtension.findStubUrl(
+						"org.springframework.cloud.contract.verifier.stubs",
+						"loanIssuance"));
+		assertThat(stubRunnerExtension.findStubUrl(
+				"org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer"))
+						.isNotNull();
+	}
+
+	@Test
+	void should_output_mappings_to_output_folder() {
+		// when
+		URL url = stubRunnerExtension.findStubUrl("fraudDetectionServer");
+
+		// then
+		assertThat(new File("target/outputmappingsforrule",
+				"fraudDetectionServer_" + url.getPort())).exists();
+	}
+
+}