Add @JsonTest annotation

Add @JsonTest and @AutoConfigureJsonTesters annotations to allow testing
of an application "slice" that only deals with JSON marshalling.

See gh-4901

spring-boot-test-autoconfigure/pom.xml

@@ -29,6 +29,11 @@
 			<artifactId>spring-boot-autoconfigure</artifactId>
 		</dependency>
 		<!-- Optional -->
+		<dependency>
+			<groupId>com.fasterxml.jackson.core</groupId>
+			<artifactId>jackson-databind</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework</groupId>
 			<artifactId>spring-test</artifactId>

spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/json/AutoConfigureJsonTesters.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.boot.test.json.BasicJsonTester;
+import org.springframework.boot.test.json.GsonTester;
+import org.springframework.boot.test.json.JacksonTester;
+import org.springframework.context.ApplicationContext;
+import org.springframework.test.context.TestExecutionListeners;
+import org.springframework.test.context.TestExecutionListeners.MergeMode;
+
+/**
+ * Annotation that can be applied to a test class to enable and configure
+ * auto-configuration of JSON Testers.
+ * <p>
+ * NOTE: {@code @AutoConfigureJsonTesters} works in conjunction with
+ * {@link JsonTesterInitializationTestExecutionListener}. If you declare your own
+ * {@link TestExecutionListeners @TestExecutionListeners} and don't
+ * {@link MergeMode#MERGE_WITH_DEFAULTS merge with defaults} you must include
+ * {@link JsonTesterInitializationTestExecutionListener} to use this annotation.
+ *
+ * @author Phillip Webb
+ * @see JsonTesterInitializationTestExecutionListener
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Inherited
+public @interface AutoConfigureJsonTesters {
+
+	/**
+	 * If {@link BasicJsonTester}, {@link JacksonTester} and {@link GsonTester} fields
+	 * should be initialized using marshallers from the {@link ApplicationContext}.
+	 */
+	boolean initFields() default true;
+
+}

spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/json/ImportJsonAutoConfiguration.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.boot.autoconfigure.ImportAutoConfiguration;
+import org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration;
+import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
+
+/**
+ * {@link ImportAutoConfiguration Auto-configuration imports} for typical JSON tests. Most
+ * tests should consider using {@link JsonTest @JsonTest} rather than using this
+ * annotation directly.
+ *
+ * @author Phillip Webb
+ * @since 1.4.0
+ * @see JsonTest
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@ImportAutoConfiguration({ GsonAutoConfiguration.class, JacksonAutoConfiguration.class })
+public @interface ImportJsonAutoConfiguration {
+
+}

spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/json/JsonExcludeFilter.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.Set;
+
+import com.fasterxml.jackson.databind.Module;
+
+import org.springframework.boot.context.TypeExcludeFilter;
+import org.springframework.boot.jackson.JsonComponent;
+import org.springframework.boot.test.autoconfigure.filter.AnnotationCustomizableTypeExcludeFilter;
+import org.springframework.context.annotation.ComponentScan.Filter;
+import org.springframework.core.annotation.AnnotatedElementUtils;
+
+/**
+ * {@link TypeExcludeFilter} for {@link JsonTest @JsonTest}.
+ *
+ * @author Phillip Webb
+ */
+class JsonExcludeFilter extends AnnotationCustomizableTypeExcludeFilter {
+
+	private static final Set<Class<?>> DEFAULT_INCLUDES;
+
+	static {
+		Set<Class<?>> includes = new LinkedHashSet<Class<?>>();
+		includes.add(Module.class);
+		includes.add(JsonComponent.class);
+		DEFAULT_INCLUDES = Collections.unmodifiableSet(includes);
+	};
+
+	private final JsonTest annotation;
+
+	JsonExcludeFilter(Class<?> testClass) {
+		this.annotation = AnnotatedElementUtils.getMergedAnnotation(testClass,
+				JsonTest.class);
+	}
+
+	@Override
+	protected boolean hasAnnotation() {
+		return this.annotation != null;
+	}
+
+	@Override
+	protected Filter[] getFilters(FilterType type) {
+		switch (type) {
+		case INCLUDE:
+			return this.annotation.includeFilters();
+		case EXCLUDE:
+			return this.annotation.excludeFilters();
+		}
+		throw new IllegalStateException("Unsupported type " + type);
+	}
+
+	@Override
+	protected boolean isUseDefaultFilters() {
+		return this.annotation.useDefaultFilters();
+	}
+
+	@Override
+	protected Set<Class<?>> getDefaultIncudes() {
+		return DEFAULT_INCLUDES;
+	}
+
+}

spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/json/JsonTest.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.test.autoconfigure.OverrideAutoConfiguration;
+import org.springframework.boot.test.autoconfigure.filter.TypeExcludeFilters;
+import org.springframework.boot.test.context.SpringBootTestContextBootstrapper;
+import org.springframework.context.annotation.ComponentScan.Filter;
+import org.springframework.test.context.BootstrapWith;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Inherited
+@BootstrapWith(SpringBootTestContextBootstrapper.class)
+@OverrideAutoConfiguration(enabled = false)
+@TypeExcludeFilters(JsonExcludeFilter.class)
+@ImportJsonAutoConfiguration
+@AutoConfigureJsonTesters
+public @interface JsonTest {
+
+	/**
+	 * Determines if default filtering should be used with
+	 * {@link SpringBootApplication @SpringBootApplication}. By default only
+	 * {@code @JsonComponent} and {@code Module} beans are included.
+	 * @see #includeFilters()
+	 * @see #excludeFilters()
+	 */
+	boolean useDefaultFilters() default true;
+
+	/**
+	 * A set of include filters which can be used to add otherwise filtered beans to the
+	 * application context.
+	 */
+	Filter[] includeFilters() default {};
+
+	/**
+	 * A set of exclude filters which can be used to filter beans that would otherwise be
+	 * added to the application context.
+	 */
+	Filter[] excludeFilters() default {};
+}

spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/json/JsonTesterInitializationTestExecutionListener.java

@@ -0,0 +1,174 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.gson.Gson;
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.ObjectFactory;
+import org.springframework.boot.test.json.BasicJsonTester;
+import org.springframework.boot.test.json.GsonTester;
+import org.springframework.boot.test.json.JacksonTester;
+import org.springframework.core.annotation.AnnotatedElementUtils;
+import org.springframework.test.context.TestContext;
+import org.springframework.test.context.TestExecutionListener;
+import org.springframework.test.context.support.AbstractTestExecutionListener;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.ReflectionUtils;
+import org.springframework.util.ReflectionUtils.FieldCallback;
+
+/**
+ * {@link TestExecutionListener} to initialize JSON tester fields.
+ *
+ * @author Phillip Webb
+ * @since 1.4.0
+ */
+public class JsonTesterInitializationTestExecutionListener
+		extends AbstractTestExecutionListener {
+
+	private static final String ASSERTJ_CLASS = "org.assertj.core.api.Assert";
+
+	private static final Map<String, Class<?>> INITALIZERS;
+
+	static {
+		Map<String, Class<?>> initializers = new LinkedHashMap<String, Class<?>>();
+		initializers.put("com.fasterxml.jackson.databind.ObjectMapper",
+				JacksonInitializer.class);
+		initializers.put("com.google.gson.Gson", GsonInitializer.class);
+		INITALIZERS = Collections.unmodifiableMap(initializers);
+	}
+
+	@Override
+	public void prepareTestInstance(TestContext testContext) throws Exception {
+		ClassLoader classLoader = getClass().getClassLoader();
+		if (ClassUtils.isPresent(ASSERTJ_CLASS, classLoader)
+				&& shouldInitializeFields(testContext)) {
+			initializeBasicJsonTesterFields(testContext);
+			initializeJsonMarshalTesterFields(classLoader, testContext);
+		}
+	}
+
+	private boolean shouldInitializeFields(TestContext testContext) {
+		AutoConfigureJsonTesters annotation = AnnotatedElementUtils.getMergedAnnotation(
+				testContext.getTestClass(), AutoConfigureJsonTesters.class);
+		return (annotation != null && annotation.initFields());
+	}
+
+	private void initializeBasicJsonTesterFields(final TestContext testContext) {
+		ReflectionUtils.doWithFields(testContext.getTestClass(), new FieldCallback() {
+
+			@Override
+			public void doWith(Field field)
+					throws IllegalArgumentException, IllegalAccessException {
+				if (BasicJsonTester.class.isAssignableFrom(field.getType())) {
+					setupField(field);
+				}
+			}
+
+			private void setupField(Field field) {
+				ReflectionUtils.makeAccessible(field);
+				Object existingInstance = ReflectionUtils.getField(field,
+						testContext.getTestInstance());
+				if (existingInstance == null) {
+					ReflectionUtils.setField(field, testContext.getTestInstance(),
+							new BasicJsonTester(testContext.getTestClass()));
+				}
+			}
+
+		});
+	}
+
+	private void initializeJsonMarshalTesterFields(ClassLoader classLoader,
+			TestContext testContext) {
+		for (Map.Entry<String, Class<?>> entry : INITALIZERS.entrySet()) {
+			if (ClassUtils.isPresent(entry.getKey(), classLoader)) {
+				initializeJsonMarshalTesterFields(classLoader, testContext,
+						entry.getKey(), entry.getValue());
+			}
+		}
+	}
+
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	private void initializeJsonMarshalTesterFields(ClassLoader classLoader,
+			TestContext testContext, String marshallerClassName, Class<?> initializer) {
+		try {
+			Constructor<?> constructor = initializer.getDeclaredConstructor();
+			ReflectionUtils.makeAccessible(constructor);
+			initializeJsonMarshalTesterFields(testContext,
+					ClassUtils.resolveClassName(marshallerClassName, classLoader),
+					(Initializer) constructor.newInstance());
+		}
+		catch (Throwable ex) {
+			throw new IllegalStateException(ex);
+		}
+	}
+
+	private <T> void initializeJsonMarshalTesterFields(final TestContext testContext,
+			final Class<T> marshallerClass, Initializer<T> initializer) {
+		initializer.initialize(testContext, new ObjectFactory<T>() {
+
+			@Override
+			public T getObject() throws BeansException {
+				return testContext.getApplicationContext().getBean(marshallerClass);
+			}
+
+		});
+	}
+
+	/**
+	 * Strategy used to initialize JSON testers without cause class not found exceptions.
+	 * @param <M> the marshaller type
+	 */
+	interface Initializer<M> {
+
+		void initialize(TestContext testContext, ObjectFactory<M> marshaller);
+
+	}
+
+	/**
+	 * {@link Initializer} for {@link JacksonTester}.
+	 */
+	static class JacksonInitializer implements Initializer<ObjectMapper> {
+
+		@Override
+		public void initialize(TestContext testContext,
+				ObjectFactory<ObjectMapper> marshaller) {
+			JacksonTester.initFields(testContext.getTestInstance(), marshaller);
+		}
+
+	}
+
+	/**
+	 * {@link Initializer} for {@link GsonTester}.
+	 */
+	static class GsonInitializer implements Initializer<Gson> {
+
+		@Override
+		public void initialize(TestContext testContext, ObjectFactory<Gson> marshaller) {
+			GsonTester.initFields(testContext.getTestInstance(), marshaller);
+		}
+
+	}
+
+}

spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/json/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-2016 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.
+ */
+
+/**
+ * Auto-configuration for JSON tests.
+ */
+package org.springframework.boot.test.autoconfigure.json;

spring-boot-test-autoconfigure/src/main/resources/META-INF/spring.factories

@@ -6,4 +6,5 @@ org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCus
 
 # Test Execution Listeners
 org.springframework.test.context.TestExecutionListener=\
-org.springframework.boot.test.autoconfigure.AutoConfigureReportTestExecutionListener
+org.springframework.boot.test.autoconfigure.AutoConfigureReportTestExecutionListener,\
+org.springframework.boot.test.autoconfigure.json.JsonTesterInitializationTestExecutionListener

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/json/ExampleBasicObject.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+/**
+ * Example object to read/write as JSON.
+ *
+ * @author Phillip Webb
+ */
+public class ExampleBasicObject {
+
+	private String value;
+
+	public String getValue() {
+		return this.value;
+	}
+
+	public void setValue(String value) {
+		this.value = value;
+	}
+
+	@Override
+	public int hashCode() {
+		return this.value.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (obj != null && obj.getClass().equals(getClass())) {
+			return this.value.equals(((ExampleBasicObject) obj).value);
+		}
+		return false;
+	}
+
+}

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/json/ExampleCustomObject.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+/**
+ * Example object to read/write as JSON via {@link ExampleJsonComponent}.
+ *
+ * @author Phillip Webb
+ */
+public class ExampleCustomObject {
+
+	private String value;
+
+	public ExampleCustomObject(String value) {
+		this.value = value;
+	}
+
+	@Override
+	public int hashCode() {
+		return this.value.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (obj != null && obj.getClass().equals(getClass())) {
+			return this.value.equals(((ExampleCustomObject) obj).value);
+		}
+		return false;
+	}
+
+	@Override
+	public String toString() {
+		return this.value;
+	}
+
+}

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/json/ExampleJsonApplication.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+/**
+ * Example {@link SpringBootApplication @SpringBootApplication} for use with
+ * {@link JsonTest @JsonTest} tests.
+ *
+ * @author Phillip Webb
+ */
+@SpringBootApplication
+public class ExampleJsonApplication {
+
+}

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/json/ExampleJsonComponent.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+import java.io.IOException;
+
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.ObjectCodec;
+import com.fasterxml.jackson.databind.DeserializationContext;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.SerializerProvider;
+
+import org.springframework.boot.jackson.JsonComponent;
+import org.springframework.boot.jackson.JsonObjectDeserializer;
+import org.springframework.boot.jackson.JsonObjectSerializer;
+
+/**
+ * Example {@link JsonComponent} for use with {@link JsonTest @JsonTest} tests.
+ *
+ * @author Phillip Webb
+ */
+@JsonComponent
+public class ExampleJsonComponent {
+
+	public static class Serializer extends JsonObjectSerializer<ExampleCustomObject> {
+
+		@Override
+		protected void serializeObject(ExampleCustomObject value, JsonGenerator jgen,
+				SerializerProvider provider) throws IOException {
+			jgen.writeStringField("value", value.toString());
+		}
+
+	}
+
+	public static class Deserialzer extends JsonObjectDeserializer<ExampleCustomObject> {
+
+		@Override
+		protected ExampleCustomObject deserializeObject(JsonParser jasonParser,
+				DeserializationContext context, ObjectCodec codec, JsonNode tree)
+						throws IOException {
+			return new ExampleCustomObject(
+					nullSafeValue(tree.get("value"), String.class));
+		}
+
+	}
+
+}

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/json/JsonTestIntegrationTests.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.boot.test.json.BasicJsonTester;
+import org.springframework.boot.test.json.GsonTester;
+import org.springframework.boot.test.json.JacksonTester;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests for {@link JsonTest}.
+ *
+ * @author Phillip Webb
+ */
+@RunWith(SpringRunner.class)
+@JsonTest
+public class JsonTestIntegrationTests {
+
+	private BasicJsonTester basicJson;
+
+	private JacksonTester<ExampleBasicObject> jacksonBasicJson;
+
+	private JacksonTester<ExampleCustomObject> jacksonCustomJson;
+
+	private GsonTester<ExampleBasicObject> gsonJson;
+
+	@Test
+	public void basicJson() throws Exception {
+		assertThat(this.basicJson.from("{\"a\":\"b\"}")).hasJsonPathStringValue("@.a");
+	}
+
+	@Test
+	public void jacksonBasic() throws Exception {
+		ExampleBasicObject object = new ExampleBasicObject();
+		object.setValue("spring");
+		assertThat(this.jacksonBasicJson.write(object)).isEqualToJson("example.json");
+	}
+
+	@Test
+	public void jacksonCustom() throws Exception {
+		ExampleCustomObject object = new ExampleCustomObject("spring");
+		assertThat(this.jacksonCustomJson.write(object)).isEqualToJson("example.json");
+	}
+
+	@Test
+	public void gson() throws Exception {
+		ExampleBasicObject object = new ExampleBasicObject();
+		object.setValue("spring");
+		assertThat(this.gsonJson.write(object)).isEqualToJson("example.json");
+	}
+
+}

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/json/JsonTestWithAutoConfigureJsonTestersTests.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.boot.test.json.BasicJsonTester;
+import org.springframework.boot.test.json.GsonTester;
+import org.springframework.boot.test.json.JacksonTester;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests for {@link JsonTest} with {@link AutoConfigureJsonTesters}.
+ *
+ * @author Phillip Webb
+ */
+@RunWith(SpringRunner.class)
+@JsonTest
+@AutoConfigureJsonTesters(initFields = false)
+public class JsonTestWithAutoConfigureJsonTestersTests {
+
+	private BasicJsonTester basicJson;
+
+	private JacksonTester<ExampleBasicObject> jacksonTester;
+
+	private GsonTester<ExampleBasicObject> gsonTester;
+
+	@Test
+	public void basicJson() throws Exception {
+		assertThat(this.basicJson).isNull();
+	}
+
+	@Test
+	public void jackson() throws Exception {
+		assertThat(this.jacksonTester).isNull();
+	}
+
+	@Test
+	public void gson() throws Exception {
+		assertThat(this.gsonTester).isNull();
+	}
+
+}

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/json/JsonTesterInitializationTestExecutionListenerTests.java

@@ -0,0 +1,179 @@
+/*
+ * Copyright 2012-2016 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.boot.test.autoconfigure.json;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.gson.GsonBuilder;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import org.springframework.boot.test.json.BasicJsonTester;
+import org.springframework.boot.test.json.GsonTester;
+import org.springframework.boot.test.json.JacksonTester;
+import org.springframework.context.support.StaticApplicationContext;
+import org.springframework.test.context.TestContext;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link JsonTesterInitializationTestExecutionListener}.
+ *
+ * @author Phillip Webb
+ */
+public class JsonTesterInitializationTestExecutionListenerTests {
+
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
+	private JsonTesterInitializationTestExecutionListener listener = new JsonTesterInitializationTestExecutionListener();
+
+	@Test
+	public void prepareTestContextShouldInitializeBasicJsonTester() throws Exception {
+		WithBasicJsonTester instance = new WithBasicJsonTester();
+		this.listener.prepareTestInstance(mockTestContext(instance));
+		assertThat(instance.tester).isNotNull();
+	}
+
+	@Test
+	public void prepareTestContextShouldInitializeJacksonTester() throws Exception {
+		WithJacksonTester instance = new WithJacksonTester();
+		this.listener.prepareTestInstance(mockTestContext(instance, new ObjectMapper()));
+		assertThat(instance.tester).isNotNull();
+	}
+
+	@Test
+	public void prepareTestContextShouldInitializeGsonTester() throws Exception {
+		WithGsonTester instance = new WithGsonTester();
+		this.listener.prepareTestInstance(
+				mockTestContext(instance, new GsonBuilder().create()));
+		assertThat(instance.tester).isNotNull();
+	}
+
+	@Test
+	public void prepareTestContextWhenInitFieldsFalseShouldNotInitializeTesters()
+			throws Exception {
+		WithInitFieldsFalse instance = new WithInitFieldsFalse();
+		this.listener.prepareTestInstance(mockTestContext(instance, new ObjectMapper()));
+		assertThat(instance.basicTester).isNull();
+		assertThat(instance.jacksonTester).isNull();
+		assertThat(instance.gsonTester).isNull();
+	}
+
+	@Test
+	public void prepareTestContextWhenInitFieldsTrueShouldInitializeTesters()
+			throws Exception {
+		WithInitFieldsTrue instance = new WithInitFieldsTrue();
+		this.listener.prepareTestInstance(mockTestContext(instance));
+		assertThat(instance.tester).isNotNull();
+	}
+
+	@Test
+	public void prepareTestContextWhenMissingAnnotationShouldNotInitializeTesters()
+			throws Exception {
+		WithoutAnnotation instance = new WithoutAnnotation();
+		this.listener.prepareTestInstance(mockTestContext(instance));
+		assertThat(instance.basicTester).isNull();
+		assertThat(instance.jacksonTester).isNull();
+		assertThat(instance.gsonTester).isNull();
+	}
+
+	@Test
+	public void prepareTestContextWhenHasJacksonTesterButNoObjectMapperBeanShouldThrowException()
+			throws Exception {
+		WithJacksonTester instance = new WithJacksonTester();
+		this.thrown.expect(IllegalStateException.class);
+		this.thrown.expectMessage("ObjectMapper");
+		this.listener.prepareTestInstance(mockTestContext(instance));
+	}
+
+	@Test
+	public void prepareTestContextWhenHasJacksonTesterButNoGsonBeanShouldThrowException()
+			throws Exception {
+		WithGsonTester instance = new WithGsonTester();
+		this.thrown.expect(IllegalStateException.class);
+		this.thrown.expectMessage("Gson");
+		this.listener.prepareTestInstance(mockTestContext(instance));
+	}
+
+	private TestContext mockTestContext(Object testInstance) {
+		return mockTestContext(testInstance, null);
+	}
+
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	private TestContext mockTestContext(Object testInstance, Object bean) {
+		TestContext testContext = mock(TestContext.class);
+		StaticApplicationContext applicationContext = new StaticApplicationContext();
+		if (bean != null) {
+			applicationContext.getBeanFactory().registerSingleton("bean", bean);
+		}
+		given(testContext.getApplicationContext()).willReturn(applicationContext);
+		given(testContext.getTestClass()).willReturn((Class) testInstance.getClass());
+		given(testContext.getTestInstance()).willReturn(testInstance);
+		return testContext;
+	}
+
+	@AutoConfigureJsonTesters
+	static class WithBasicJsonTester {
+
+		private BasicJsonTester tester;
+
+	}
+
+	@AutoConfigureJsonTesters
+	static class WithJacksonTester {
+
+		private JacksonTester<Object> tester;
+	}
+
+	@AutoConfigureJsonTesters
+	static class WithGsonTester {
+
+		private GsonTester<Object> tester;
+	}
+
+	@AutoConfigureJsonTesters(initFields = false)
+	static class WithInitFieldsFalse {
+
+		private BasicJsonTester basicTester;
+
+		private JacksonTester<Object> jacksonTester;
+
+		private GsonTester<Object> gsonTester;
+
+	}
+
+	@AutoConfigureJsonTesters(initFields = true)
+	static class WithInitFieldsTrue {
+
+		private BasicJsonTester tester;
+
+	}
+
+	static class WithoutAnnotation {
+
+		private BasicJsonTester basicTester;
+
+		private JacksonTester<Object> jacksonTester;
+
+		private GsonTester<Object> gsonTester;
+
+	}
+
+}

spring-boot-test-autoconfigure/src/test/resources/org/springframework/boot/test/autoconfigure/json/example.json

@@ -0,0 +1,3 @@
+{
+   "value" : "spring"
+}