From 81c28166935fb59666aef2d0736d4f5fd8bfce5c Mon Sep 17 00:00:00 2001
From: Andy Wilkinson <awilkinson@pivotal.io>
Date: Wed, 8 Mar 2017 12:35:30 +0000
Subject: [PATCH] Relax field type validation when marked as optional and value
 is null

Previously, if a field was marked as optional and it appeared in a
payload with a null value a failure would occur if the field's type
was configured to be a JsonFieldType other than NULL.

This commit relaxes this restriction so that a null value is tolerated
when a field has been marked as optional.

Closes gh-365
---
 .../restdocs/payload/JsonContentHandler.java  |  6 ++-
 .../payload/JsonContentHandlerTests.java      | 54 +++++++++++++++++++
 2 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100644 spring-restdocs-core/src/test/java/org/springframework/restdocs/payload/JsonContentHandlerTests.java

diff --git a/spring-restdocs-core/src/main/java/org/springframework/restdocs/payload/JsonContentHandler.java b/spring-restdocs-core/src/main/java/org/springframework/restdocs/payload/JsonContentHandler.java
index f1fff9ce..ae569937 100644
--- a/spring-restdocs-core/src/main/java/org/springframework/restdocs/payload/JsonContentHandler.java
+++ b/spring-restdocs-core/src/main/java/org/springframework/restdocs/payload/JsonContentHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2016 the original author or authors.
+ * Copyright 2014-2017 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.
@@ -108,7 +108,9 @@ class JsonContentHandler implements ContentHandler {
 			JsonFieldType actualFieldType = this.fieldTypeResolver
 					.resolveFieldType(fieldDescriptor.getPath(), readContent());
 			if (descriptorFieldType == JsonFieldType.VARIES
-					|| descriptorFieldType == actualFieldType) {
+					|| descriptorFieldType == actualFieldType
+					|| (fieldDescriptor.isOptional()
+							&& actualFieldType == JsonFieldType.NULL)) {
 				return descriptorFieldType;
 			}
 			throw new FieldTypesDoNotMatchException(fieldDescriptor, actualFieldType);
diff --git a/spring-restdocs-core/src/test/java/org/springframework/restdocs/payload/JsonContentHandlerTests.java b/spring-restdocs-core/src/test/java/org/springframework/restdocs/payload/JsonContentHandlerTests.java
new file mode 100644
index 00000000..b5f74523
--- /dev/null
+++ b/spring-restdocs-core/src/test/java/org/springframework/restdocs/payload/JsonContentHandlerTests.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2014-2017 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
+ *
+ *      http://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.payload;
+
+import java.io.IOException;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Tests for {@link JsonContentHandler}.
+ *
+ * @author Andy Wilkinson
+ */
+public class JsonContentHandlerTests {
+
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
+	@Test
+	public void typeForFieldWithNullValueMustMatch() throws IOException {
+		this.thrown.expect(FieldTypesDoNotMatchException.class);
+		new JsonContentHandler("{\"a\": null}".getBytes())
+				.determineFieldType(new FieldDescriptor("a").type(JsonFieldType.STRING));
+	}
+
+	@Test
+	public void typeForOptionalFieldWithNullValueDoesNotHaveToMatch() throws IOException {
+		Object fieldType = new JsonContentHandler("{\"a\": null}".getBytes())
+				.determineFieldType(
+						new FieldDescriptor("a").type(JsonFieldType.STRING).optional());
+		assertThat((JsonFieldType) fieldType, is(equalTo(JsonFieldType.STRING)));
+	}
+
+}