Add @PropertyMapping support

Add @PropertyMapping annotation which can be used to mark annotation
attributes that should contribute Environment properties.

Provides a quick way for tests to change auto-configuration behavior in
a structured way.

Fixes gh-4901

spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/properties/AnnotationsPropertySource.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.properties;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Method;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.core.env.EnumerablePropertySource;
+import org.springframework.util.ObjectUtils;
+import org.springframework.util.ReflectionUtils;
+import org.springframework.util.StringUtils;
+
+/**
+ * {@link EnumerablePropertySource} to adapt annotations marked with
+ * {@link PropertyMapping @PropertyMapping}.
+ *
+ * @author Phillip Webb
+ * @since 1.4.0
+ */
+public class AnnotationsPropertySource extends EnumerablePropertySource<Class<?>> {
+
+	private static final Pattern CAMEL_CASE_PATTERN = Pattern.compile("([^A-Z-])([A-Z])");
+
+	private final Map<String, Object> properties;
+
+	public AnnotationsPropertySource(Class<?> source) {
+		this("Annotations", source);
+	}
+
+	public AnnotationsPropertySource(String name, Class<?> source) {
+		super(name, source);
+		this.properties = getProperties(source);
+	}
+
+	private Map<String, Object> getProperties(Class<?> source) {
+		Map<String, Object> properties = new LinkedHashMap<String, Object>();
+		collectProperties(source, properties);
+		return Collections.unmodifiableMap(properties);
+	}
+
+	private void collectProperties(Class<?> source, Map<String, Object> properties) {
+		if (source != null) {
+			for (Annotation annotation : source.getDeclaredAnnotations()) {
+				if (!AnnotationUtils.isInJavaLangAnnotationPackage(annotation)) {
+					PropertyMapping typeMapping = AnnotationUtils.getAnnotation(
+							annotation.annotationType(), PropertyMapping.class);
+					for (Method attribute : annotation.annotationType()
+							.getDeclaredMethods()) {
+						collectProperties(annotation, attribute, typeMapping, properties);
+					}
+				}
+			}
+			collectProperties(source.getSuperclass(), properties);
+		}
+	}
+
+	private void collectProperties(Annotation annotation, Method attribute,
+			PropertyMapping typeMapping, Map<String, Object> properties) {
+		PropertyMapping attributeMapping = AnnotationUtils.getAnnotation(attribute,
+				PropertyMapping.class);
+		if (isMapped(typeMapping, attributeMapping)) {
+			String name = getName(typeMapping, attributeMapping, attribute);
+			ReflectionUtils.makeAccessible(attribute);
+			Object value = ReflectionUtils.invokeMethod(attribute, annotation);
+			putProperties(name, value, properties);
+		}
+	}
+
+	private boolean isMapped(PropertyMapping typeMapping,
+			PropertyMapping attributeMapping) {
+		if (attributeMapping != null) {
+			return attributeMapping.map();
+		}
+		return (typeMapping != null && typeMapping.map());
+	}
+
+	private String getName(PropertyMapping typeMapping, PropertyMapping attributeMapping,
+			Method attribute) {
+		String prefix = (typeMapping == null ? "" : typeMapping.value());
+		String name = (attributeMapping == null ? "" : attributeMapping.value());
+		if (!StringUtils.hasText(name)) {
+			name = toKebabCase(attribute.getName());
+		}
+		return dotAppend(prefix, name);
+	}
+
+	private String toKebabCase(String name) {
+		Matcher matcher = CAMEL_CASE_PATTERN.matcher(name);
+		StringBuffer result = new StringBuffer();
+		while (matcher.find()) {
+			matcher.appendReplacement(result,
+					matcher.group(1) + '-' + StringUtils.uncapitalize(matcher.group(2)));
+		}
+		matcher.appendTail(result);
+		return result.toString().toLowerCase();
+	}
+
+	private String dotAppend(String prefix, String postfix) {
+		prefix = (prefix == null ? "" : prefix);
+		if (StringUtils.hasText(prefix)) {
+			return (prefix.endsWith(".") ? prefix + postfix : prefix + "." + postfix);
+		}
+		return postfix;
+	}
+
+	private void putProperties(String name, Object value,
+			Map<String, Object> properties) {
+		if (ObjectUtils.isArray(value)) {
+			Object[] array = ObjectUtils.toObjectArray(value);
+			for (int i = 0; i < array.length; i++) {
+				properties.put(name + "[" + i + "]", array[i]);
+			}
+		}
+		else {
+			properties.put(name, value);
+		}
+	}
+
+	@Override
+	public boolean containsProperty(String name) {
+		return this.properties.containsKey(name);
+	}
+
+	@Override
+	public Object getProperty(String name) {
+		return this.properties.get(name);
+	}
+
+	@Override
+	public String[] getPropertyNames() {
+		return StringUtils.toStringArray(this.properties.keySet());
+	}
+
+	public boolean isEmpty() {
+		return this.properties.isEmpty();
+	}
+
+	@Override
+	public int hashCode() {
+		return this.properties.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (obj == this) {
+			return true;
+		}
+		if (obj == null || getClass() != obj.getClass()) {
+			return false;
+		}
+		return this.properties.equals(((AnnotationsPropertySource) obj).properties);
+	}
+
+}

spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/properties/PropertyMapping.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.properties;
+
+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.context.annotation.PropertySource;
+import org.springframework.test.context.TestPropertySource;
+
+/**
+ * Indicates that attributes from a test annotation should be mapped into a
+ * {@link PropertySource}. Can be used at the type level, or on individual attributes. For
+ * example, the following annotation declaration: <pre class="code">
+ * &#064;Retention(RUNTIME)
+ * &#064;PropertyMapping("my.example")
+ * public &#064;interface Example {
+ *
+ *   String name();
+ *
+ * }
+ * </pre> When used on a test class as follows: <pre class="code">
+ * &#064;Example(name="Spring")
+ * public class MyTest {
+ * }
+ * </pre> will result in a {@literal my.example.name} property being added with the value
+ * {@literal "Spring"}.
+ * <p>
+ *
+ * @author Phillip Webb
+ * @since 1.4.0
+ * @see AnnotationsPropertySource
+ * @see TestPropertySource
+ */
+@Documented
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.TYPE, ElementType.METHOD })
+public @interface PropertyMapping {
+
+	/**
+	 * Defines the property mapping. When used at the type-level, this value will be used
+	 * as a prefix for all mapped attributes. When used on an attribute, the value
+	 * overrides the generated (kebab case) name.
+	 */
+	String value() default "";
+
+	/**
+	 * Determines if mapping should occur. When specified at the type-level indicates if
+	 * mapping should occur by default or not. When used at the attribute-level, overrides
+	 * the type-level default.
+	 */
+	boolean map() default true;
+
+}

spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/properties/PropertyMappingContextCustomizer.java

@@ -0,0 +1,94 @@
+/*
+ * 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.properties;
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.config.BeanPostProcessor;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.core.env.Environment;
+import org.springframework.stereotype.Component;
+import org.springframework.test.context.ContextCustomizer;
+import org.springframework.test.context.MergedContextConfiguration;
+import org.springframework.util.Assert;
+
+/**
+ * {@link ContextCustomizer} to map annotation attributes to {@link Environment}
+ * properties.
+ *
+ * @author Phillip Webb
+ */
+class PropertyMappingContextCustomizer implements ContextCustomizer {
+
+	private final AnnotationsPropertySource propertySource;
+
+	PropertyMappingContextCustomizer(AnnotationsPropertySource propertySource) {
+		this.propertySource = propertySource;
+	}
+
+	@Override
+	public void customizeContext(ConfigurableApplicationContext context,
+			MergedContextConfiguration mergedContextConfiguration) {
+		if (!this.propertySource.isEmpty()) {
+			context.getEnvironment().getPropertySources().addFirst(this.propertySource);
+		}
+		context.getBeanFactory().registerSingleton(
+				PropertyMappingCheckBeanPostProcessor.class.getName(),
+				new PropertyMappingCheckBeanPostProcessor());
+	}
+
+	@Override
+	public int hashCode() {
+		return this.propertySource.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		return (obj != null && getClass().equals(obj.getClass()) && this.propertySource
+				.equals(((PropertyMappingContextCustomizer) obj).propertySource));
+	}
+
+	/**
+	 * {@link BeanPostProcessor} to check that {@link PropertyMapping} is only used on
+	 * test classes.
+	 */
+	static class PropertyMappingCheckBeanPostProcessor implements BeanPostProcessor {
+
+		@Override
+		public Object postProcessBeforeInitialization(Object bean, String beanName)
+				throws BeansException {
+			Class<?> beanClass = bean.getClass();
+			boolean hasComponent = AnnotationUtils.findAnnotation(beanClass,
+					Component.class) != null;
+			boolean hasPropertyMapping = AnnotationUtils.findAnnotation(beanClass,
+					PropertyMapping.class) != null;
+			if (hasComponent) {
+				Assert.state(!hasPropertyMapping,
+						"@PropertyMapping annotations can only be used on test classes");
+			}
+			return bean;
+		}
+
+		@Override
+		public Object postProcessAfterInitialization(Object bean, String beanName)
+				throws BeansException {
+			return bean;
+		}
+
+	}
+
+}

spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/properties/PropertyMappingContextCustomizerFactory.java

@@ -0,0 +1,42 @@
+/*
+ * 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.properties;
+
+import java.util.List;
+
+import org.springframework.core.env.Environment;
+import org.springframework.test.context.ContextConfigurationAttributes;
+import org.springframework.test.context.ContextCustomizer;
+import org.springframework.test.context.ContextCustomizerFactory;
+
+/**
+ * {@link ContextCustomizerFactory} to map annotation attributes to {@link Environment}
+ * properties.
+ *
+ * @author Phillip Webb
+ */
+class PropertyMappingContextCustomizerFactory implements ContextCustomizerFactory {
+
+	@Override
+	public ContextCustomizer createContextCustomizer(Class<?> testClass,
+			List<ContextConfigurationAttributes> configurationAttributes) {
+		AnnotationsPropertySource propertySource = new AnnotationsPropertySource(
+				testClass);
+		return new PropertyMappingContextCustomizer(propertySource);
+	}
+
+}

spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/properties/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.
+ */
+
+/**
+ * Support for mapping annotation attribute values in the Spring {@code Environment}.
+ */
+package org.springframework.boot.test.autoconfigure.properties;

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

@@ -1,6 +1,7 @@
 # Spring Test ContextCustomizerFactories
 org.springframework.test.context.ContextCustomizerFactory=\
-org.springframework.boot.test.autoconfigure.OverrideAutoConfigurationContextCustomizerFactory
+org.springframework.boot.test.autoconfigure.OverrideAutoConfigurationContextCustomizerFactory,\
+org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizerFactory
 
 # Test Execution Listeners
 org.springframework.test.context.TestExecutionListener=\

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/properties/AnnotationsPropertySourceTests.java

@@ -0,0 +1,265 @@
+/*
+ * 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.properties;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link AnnotationsPropertySource}.
+ *
+ * @author Phillip Webb
+ */
+public class AnnotationsPropertySourceTests {
+
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
+	@Test
+	public void createWhenSourceIsNullShouldThrowException() throws Exception {
+		this.thrown.expect(IllegalArgumentException.class);
+		this.thrown.expectMessage("Property source must not be null");
+		new AnnotationsPropertySource(null);
+	}
+
+	@Test
+	public void propertiesWhenHasNoAnnotationShouldBeEmpty() throws Exception {
+		AnnotationsPropertySource source = new AnnotationsPropertySource(
+				NoAnnotation.class);
+		assertThat(source.getPropertyNames()).isEmpty();
+		assertThat(source.getProperty("value")).isNull();
+	}
+
+	@Test
+	public void propertiesWhenHasTypeLevelAnnotationShouldUseAttributeName()
+			throws Exception {
+		AnnotationsPropertySource source = new AnnotationsPropertySource(TypeLevel.class);
+		assertThat(source.getPropertyNames()).containsExactly("value");
+		assertThat(source.getProperty("value")).isEqualTo("abc");
+	}
+
+	@Test
+	public void propertiesWhenHasTypeLevelWithPrefixShouldUsePrefixedName()
+			throws Exception {
+		AnnotationsPropertySource source = new AnnotationsPropertySource(
+				TypeLevelWithPrefix.class);
+		assertThat(source.getPropertyNames()).containsExactly("test.value");
+		assertThat(source.getProperty("test.value")).isEqualTo("abc");
+	}
+
+	@Test
+	public void propertiesWhenHasAttributeLevelWithPrefixShouldUsePrefixedName()
+			throws Exception {
+		AnnotationsPropertySource source = new AnnotationsPropertySource(
+				AttributeLevelWithPrefix.class);
+		assertThat(source.getPropertyNames()).containsExactly("test");
+		assertThat(source.getProperty("test")).isEqualTo("abc");
+	}
+
+	@Test
+	public void propertiesWhenHasTypeAndAttributeLevelWithPrefixShouldUsePrefixedName()
+			throws Exception {
+		AnnotationsPropertySource source = new AnnotationsPropertySource(
+				TypeAndAttributeLevelWithPrefix.class);
+		assertThat(source.getPropertyNames()).containsExactly("test.example");
+		assertThat(source.getProperty("test.example")).isEqualTo("abc");
+	}
+
+	@Test
+	public void propertiesWhenNotMappedAtTypeLevelShouldIgnoreAttributes()
+			throws Exception {
+		AnnotationsPropertySource source = new AnnotationsPropertySource(
+				NotMappedAtTypeLevel.class);
+		assertThat(source.getPropertyNames()).containsExactly("value");
+		assertThat(source.getProperty("ignore")).isNull();
+	}
+
+	@Test
+	public void propertiesWhenNotMappedAtAttributeLevelShouldIgnoreAttributes()
+			throws Exception {
+		AnnotationsPropertySource source = new AnnotationsPropertySource(
+				NotMappedAtAttributeLevel.class);
+		assertThat(source.getPropertyNames()).containsExactly("value");
+		assertThat(source.getProperty("ignore")).isNull();
+	}
+
+	@Test
+	public void propertiesWhenCountainsArryasShouldExpandNames() throws Exception {
+		AnnotationsPropertySource source = new AnnotationsPropertySource(Arrays.class);
+		assertThat(source.getPropertyNames()).contains("strings[0]", "strings[1]",
+				"classes[0]", "classes[1]", "ints[0]", "ints[1]", "longs[0]", "longs[1]",
+				"floats[0]", "floats[1]", "doubles[0]", "doubles[1]", "booleans[0]",
+				"booleans[1]");
+		assertThat(source.getProperty("strings[0]")).isEqualTo("a");
+		assertThat(source.getProperty("strings[1]")).isEqualTo("b");
+		assertThat(source.getProperty("classes[0]")).isEqualTo(Integer.class);
+		assertThat(source.getProperty("classes[1]")).isEqualTo(Long.class);
+		assertThat(source.getProperty("ints[0]")).isEqualTo(1);
+		assertThat(source.getProperty("ints[1]")).isEqualTo(2);
+		assertThat(source.getProperty("longs[0]")).isEqualTo(1L);
+		assertThat(source.getProperty("longs[1]")).isEqualTo(2L);
+		assertThat(source.getProperty("floats[0]")).isEqualTo(1.0f);
+		assertThat(source.getProperty("floats[1]")).isEqualTo(2.0f);
+		assertThat(source.getProperty("doubles[0]")).isEqualTo(1.0);
+		assertThat(source.getProperty("doubles[1]")).isEqualTo(2.0);
+		assertThat(source.getProperty("booleans[0]")).isEqualTo(false);
+		assertThat(source.getProperty("booleans[1]")).isEqualTo(true);
+	}
+
+	@Test
+	public void propertiesWhenHasCamelCaseShouldConvertToKebabCase() throws Exception {
+		AnnotationsPropertySource source = new AnnotationsPropertySource(
+				CamelCaseToKebabCase.class);
+		assertThat(source.getPropertyNames()).contains("camel-case-to-kebab-case");
+	}
+
+	static class NoAnnotation {
+
+	}
+
+	@TypeLevelAnnotation("abc")
+	static class TypeLevel {
+
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@PropertyMapping
+	static @interface TypeLevelAnnotation {
+
+		String value();
+
+	}
+
+	@TypeLevelWithPrefixAnnotation("abc")
+	static class TypeLevelWithPrefix {
+
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@PropertyMapping("test")
+	static @interface TypeLevelWithPrefixAnnotation {
+
+		String value();
+
+	}
+
+	@AttributeLevelWithPrefixAnnotation("abc")
+	static class AttributeLevelWithPrefix {
+
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	static @interface AttributeLevelWithPrefixAnnotation {
+
+		@PropertyMapping("test")
+		String value();
+
+	}
+
+	@TypeAndAttributeLevelWithPrefixAnnotation("abc")
+	static class TypeAndAttributeLevelWithPrefix {
+
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@PropertyMapping("test")
+	static @interface TypeAndAttributeLevelWithPrefixAnnotation {
+
+		@PropertyMapping("example")
+		String value();
+
+	}
+
+	@NotMappedAtTypeLevelAnnotation("abc")
+	static class NotMappedAtTypeLevel {
+
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@PropertyMapping(map = false)
+	static @interface NotMappedAtTypeLevelAnnotation {
+
+		@PropertyMapping
+		String value();
+
+		String ignore() default "xyz";
+
+	}
+
+	@NotMappedAtAttributeLevelAnnotation("abc")
+	static class NotMappedAtAttributeLevel {
+
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@PropertyMapping
+	static @interface NotMappedAtAttributeLevelAnnotation {
+
+		String value();
+
+		@PropertyMapping(map = false)
+		String ignore() default "xyz";
+
+	}
+
+	@ArraysAnnotation(strings = { "a", "b" }, classes = { Integer.class,
+			Long.class }, ints = { 1, 2 }, longs = { 1, 2 }, floats = { 1.0f,
+					2.0f }, doubles = { 1.0, 2.0 }, booleans = { false, true })
+	static class Arrays {
+
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@PropertyMapping
+	static @interface ArraysAnnotation {
+
+		String[] strings();
+
+		Class<?>[] classes();
+
+		int[] ints();
+
+		long[] longs();
+
+		float[] floats();
+
+		double[] doubles();
+
+		boolean[] booleans();
+
+	}
+
+	@CamelCaseToKebabCaseAnnotation
+	static class CamelCaseToKebabCase {
+
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@PropertyMapping
+	static @interface CamelCaseToKebabCaseAnnotation {
+
+		String camelCaseToKebabCase() default "abc";
+
+	}
+
+}

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/properties/ExampleMapping.java

@@ -0,0 +1,33 @@
+/*
+ * 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.properties;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * Example {@link PropertyMapping} annotation for use wuth {@link PropertyMappingTests}.
+ *
+ * @author Phillip Webb
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@PropertyMapping
+@interface ExampleMapping {
+
+	String exampleProperty();
+
+}

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/properties/PropertyMappingContextCustomizerFactoryTests.java

@@ -0,0 +1,158 @@
+/*
+ * 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.properties;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import org.springframework.beans.factory.BeanCreationException;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.test.context.ContextCustomizer;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verifyZeroInteractions;
+
+/**
+ * Tests for {@link PropertyMappingContextCustomizerFactory}.
+ *
+ * @author Phillip Webb
+ */
+public class PropertyMappingContextCustomizerFactoryTests {
+
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
+	private PropertyMappingContextCustomizerFactory factory = new PropertyMappingContextCustomizerFactory();
+
+	@Test
+	public void getContextCustomizerWhenHasNoMappingShouldNotAddPropertySource() {
+		ContextCustomizer customizer = this.factory
+				.createContextCustomizer(NoMapping.class, null);
+		ConfigurableApplicationContext context = mock(
+				ConfigurableApplicationContext.class);
+		ConfigurableEnvironment environment = mock(ConfigurableEnvironment.class);
+		ConfigurableListableBeanFactory beanFactory = mock(
+				ConfigurableListableBeanFactory.class);
+		given(context.getEnvironment()).willReturn(environment);
+		given(context.getBeanFactory()).willReturn(beanFactory);
+		customizer.customizeContext(context, null);
+		verifyZeroInteractions(environment);
+	}
+
+	@Test
+	public void getContextCustomizerWhenHasTypeMappingShouldReturnCustomizer() {
+		ContextCustomizer customizer = this.factory
+				.createContextCustomizer(TypeMapping.class, null);
+		assertThat(customizer).isNotNull();
+	}
+
+	@Test
+	public void getContextCustomizerWhenHasAttributeMappingShouldReturnCustomizer() {
+		ContextCustomizer customizer = this.factory
+				.createContextCustomizer(AttributeMapping.class, null);
+		assertThat(customizer).isNotNull();
+	}
+
+	@Test
+	public void hashCodeAndEqualsShoudBeBasedOnPropertyValues() throws Exception {
+		ContextCustomizer customizer1 = this.factory
+				.createContextCustomizer(TypeMapping.class, null);
+		ContextCustomizer customizer2 = this.factory
+				.createContextCustomizer(AttributeMapping.class, null);
+		ContextCustomizer customizer3 = this.factory
+				.createContextCustomizer(OtherMapping.class, null);
+		assertThat(customizer1.hashCode()).isEqualTo(customizer2.hashCode());
+		assertThat(customizer1).isEqualTo(customizer1).isEqualTo(customizer2)
+				.isNotEqualTo(customizer3);
+	}
+
+	@Test
+	public void prepareContextShouldAddPropertySource() throws Exception {
+		ContextCustomizer customizer = this.factory
+				.createContextCustomizer(AttributeMapping.class, null);
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		customizer.customizeContext(context, null);
+		assertThat(context.getEnvironment().getProperty("mapped")).isEqualTo("Mapped");
+	}
+
+	@Test
+	public void propertyMappingShouldNotBeUsedWithComponent() throws Exception {
+		ContextCustomizer customizer = this.factory
+				.createContextCustomizer(AttributeMapping.class, null);
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		context.register(ConfigMapping.class);
+		customizer.customizeContext(context, null);
+		this.thrown.expect(BeanCreationException.class);
+		this.thrown.expectMessage(
+				"@PropertyMapping annotations can only be used on test classes");
+		context.refresh();
+	}
+
+	@NoMappingAnnotation
+	static class NoMapping {
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	static @interface NoMappingAnnotation {
+
+	}
+
+	@TypeMappingAnnotation
+	static class TypeMapping {
+	}
+
+	@Configuration
+	@TypeMappingAnnotation
+	static class ConfigMapping {
+
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@PropertyMapping
+	static @interface TypeMappingAnnotation {
+
+		String mapped() default "Mapped";
+
+	}
+
+	@AttributeMappingAnnotation
+	static class AttributeMapping {
+	}
+
+	@AttributeMappingAnnotation("Other")
+	static class OtherMapping {
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	static @interface AttributeMappingAnnotation {
+
+		@PropertyMapping("mapped")
+		String value() default "Mapped";
+
+	}
+
+}

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/properties/PropertyMappingTests.java

@@ -0,0 +1,45 @@
+/*
+ * 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.properties;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.core.env.Environment;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests for {@link PropertyMapping @PropertyMapping} annotaions.
+ *
+ * @author Phillip Webb
+ */
+@RunWith(SpringRunner.class)
+@ExampleMapping(exampleProperty = "abc")
+public class PropertyMappingTests {
+
+	@Autowired
+	private Environment environment;
+
+	@Test
+	public void hasProperty() throws Exception {
+		assertThat(this.environment.getProperty("example-property")).isEqualTo("abc");
+	}
+
+}