Add YamlPropertySourceFactory and @TestYamlPropertySource

that can be applied to a test class to add PropertySource
loaded from YAML files to the Environment

This commit introduces new functionality to load properties
from YAML files in tests. The @TestYamlPropertySource annotation
is added to allow test classes to specify YAML files as property sources.

The @TestYamlPropertySource provides a convenient alternative for @TestPropertySource(factory=YamlPropertySourceFactory.class).

The YamlPropertySourceFactory class is also introduced to enable the loading of YAML files into the Environment through @TestPropertySource.

spring-boot-project/spring-boot-docs/src/docs/antora/modules/reference/pages/features/external-config.adoc

@@ -26,7 +26,7 @@ Sources are considered in the following order:
 . `properties` attribute on your tests.
   Available on javadoc:org.springframework.boot.test.context.SpringBootTest[format=annotation] and the xref:testing/spring-boot-applications.adoc#testing.spring-boot-applications.autoconfigured-tests[test annotations for testing a particular slice of your application].
 . javadoc:{url-spring-framework-javadoc}/org.springframework.test.context.DynamicPropertySource[format=annotation] annotations in your tests.
-. javadoc:{url-spring-framework-javadoc}/org.springframework.test.context.TestPropertySource[format=annotation] annotations on your tests.
+. javadoc:{url-spring-framework-javadoc}/org.springframework.test.context.TestPropertySource[format=annotation] or javadoc:org.springframework.boot.test.context.TestYamlPropertySource[format=annotation] annotations on your tests.
 . xref:using/devtools.adoc#using.devtools.globalsettings[Devtools global settings properties] in the `$HOME/.config/spring-boot` directory when devtools is active.
 
 Config data files are considered in the following order:
@@ -525,7 +525,7 @@ The lines immediately before and after the separator must not be same comment pr
 TIP: Multi-document property files are often used in conjunction with activation properties such as `spring.config.activate.on-profile`.
 See the xref:features/external-config.adoc#features.external-config.files.activation-properties[next section] for details.
 
-WARNING: Multi-document property files cannot be loaded by using the `@PropertySource` or `@TestPropertySource` annotations.
+WARNING: Multi-document property files cannot be loaded by using the `@PropertySource`, `@TestPropertySource` or `@TestYamlPropertySource` annotations.
 
 
 
@@ -640,7 +640,7 @@ TIP: Properties that use the `[index]` notation can be bound to Java `List` or `
 For more details see the xref:features/external-config.adoc#features.external-config.typesafe-configuration-properties[] section below.
 
 WARNING: YAML files cannot be loaded by using the `@PropertySource` or `@TestPropertySource` annotations.
-So, in the case that you need to load values that way, you need to use a properties file.
+So, in the case that you need to load values that way, you need to use a properties file or use `@TestYamlPropertySource`
 
 
 

spring-boot-project/spring-boot-test/build.gradle

@@ -59,5 +59,5 @@ dependencies {
 	testImplementation("org.testng:testng")
 
 	testRuntimeOnly("org.junit.vintage:junit-vintage-engine")
+	testRuntimeOnly("org.yaml:snakeyaml")
 }
-

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/TestYamlPropertySource.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2012-2024 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.boot.test.context;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Repeatable;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.core.annotation.AliasFor;
+import org.springframework.test.context.TestPropertySource;
+
+/**
+ * {@code @TestYamlPropertySource} is an annotation that can be applied to a test class to
+ * configure the locations of YAML files and inlined properties to be added to the
+ * Environment's set of PropertySources for an ApplicationContext for integration tests.
+ * <p>
+ * Provides a convenient alternative for
+ * {@code @TestPropertySource(locations = "...", factory = YamlPropertySourceFactory.class)}.
+ * <p>
+ * {@code @TestYamlPropertySource} should be considered as {@code @TestPropertySource} but
+ * for YAML files. It intentionally does not support multi-document YAML files to maintain
+ * consistency with the behavior of {@code @TestPropertySource}.
+ *
+ * @author Dmytro Nosan
+ * @since 3.5.0
+ * @see YamlPropertySourceFactory
+ * @see TestPropertySource
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Inherited
+@TestPropertySource(factory = YamlPropertySourceFactory.class)
+@Repeatable(TestYamlPropertySources.class)
+public @interface TestYamlPropertySource {
+
+	/**
+	 * Alias for {@link TestPropertySource#value()}.
+	 * @return The resource locations of YAML files.
+	 * @see TestPropertySource#value() for more details.
+	 */
+	@AliasFor(attribute = "value", annotation = TestPropertySource.class)
+	String[] value() default {};
+
+	/**
+	 * Alias for {@link TestPropertySource#locations()}.
+	 * @return The resource locations of YAML files.
+	 * @see TestPropertySource#locations() for more details.
+	 */
+	@AliasFor(attribute = "locations", annotation = TestPropertySource.class)
+	String[] locations() default {};
+
+	/**
+	 * Alias for {@link TestPropertySource#inheritLocations()}.
+	 * @return Whether test property source {@link #locations} from superclasses and
+	 * enclosing classes should be <em>inherited</em>.
+	 * @see TestPropertySource#inheritLocations() for more details.
+	 */
+	@AliasFor(attribute = "inheritLocations", annotation = TestPropertySource.class)
+	boolean inheritLocations() default true;
+
+	/**
+	 * Alias for {@link TestPropertySource#properties()}.
+	 * @return <em>Inlined properties</em> in the form of <em>key-value</em> pairs that
+	 * should be added to the Environment
+	 * @see TestPropertySource#properties() for more details.
+	 */
+	@AliasFor(attribute = "properties", annotation = TestPropertySource.class)
+	String[] properties() default {};
+
+	/**
+	 * Alias for {@link TestPropertySource#inheritProperties()}.
+	 * @return Whether inlined test {@link #properties} from superclasses and enclosing
+	 * classes should be <em>inherited</em>.
+	 * @see TestPropertySource#inheritProperties() for more details.
+	 */
+	@AliasFor(attribute = "inheritProperties", annotation = TestPropertySource.class)
+	boolean inheritProperties() default true;
+
+}

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/TestYamlPropertySources.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2012-2024 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.boot.test.context;
+
+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;
+
+/**
+ * {@code @TestYamlPropertySources} is a container for one or more
+ * {@link TestYamlPropertySource @TestYamlPropertySource} declarations.
+ *
+ * @author Dmytro Nosan
+ * @since 3.5.0
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Inherited
+public @interface TestYamlPropertySources {
+
+	/**
+	 * An array of one or more {@link TestYamlPropertySource @TestYamlPropertySource}
+	 * declarations.
+	 * @return {@link TestYamlPropertySource @TestYamlPropertySource} annotations.
+	 */
+	TestYamlPropertySource[] value();
+
+}

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/YamlPropertySourceFactory.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2012-2024 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.boot.test.context;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.List;
+
+import org.springframework.boot.env.YamlPropertySourceLoader;
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.PropertySource;
+import org.springframework.core.io.Resource;
+import org.springframework.core.io.support.EncodedResource;
+import org.springframework.core.io.support.PropertySourceFactory;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+/**
+ * An implementation of {@link PropertySourceFactory} that delegates the loading of
+ * {@code PropertySource} to {@link YamlPropertySourceLoader}.
+ * <p>
+ * Even though {@link YamlPropertySourceLoader} supports multi-document YAML files, the
+ * {@code YamlPropertySourceFactory} intentionally does not allow this.
+ *
+ * @author Dmytro Nosan
+ * @since 3.5.0
+ * @see TestYamlPropertySource
+ */
+public class YamlPropertySourceFactory implements PropertySourceFactory {
+
+	private static final YamlPropertySourceLoader loader = new YamlPropertySourceLoader();
+
+	@Override
+	public PropertySource<?> createPropertySource(String name, EncodedResource encodedResource) throws IOException {
+		Resource resource = encodedResource.getResource();
+		String propertySourceName = getPropertySourceName(name, resource);
+		List<PropertySource<?>> propertySources = loader.load(propertySourceName, resource);
+		Assert.isTrue(propertySources.size() <= 1, () -> resource + " is a multi-document YAML file");
+		if (propertySources.isEmpty()) {
+			return new MapPropertySource(name, Collections.emptyMap());
+		}
+		return propertySources.get(0);
+	}
+
+	private static String getPropertySourceName(String name, Resource resource) {
+		if (StringUtils.hasText(name)) {
+			return name;
+		}
+		String description = resource.getDescription();
+		if (StringUtils.hasText(description)) {
+			return description;
+		}
+		return resource.getClass().getSimpleName() + "@" + System.identityHashCode(resource);
+	}
+
+}

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/context/TestYamlPropertySourceIntegrationTests.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2012-2024 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.boot.test.context;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.env.Environment;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests for {@link YamlPropertySourceFactory} with
+ * {@link TestYamlPropertySource}.
+ *
+ * @author Dmytro Nosan
+ */
+@SpringJUnitConfig
+@TestYamlPropertySource({ "test.yaml", "test1.yaml" })
+@TestYamlPropertySource(locations = "test2.yaml", properties = "key:value")
+class TestYamlPropertySourceIntegrationTests {
+
+	@Autowired
+	private Environment environment;
+
+	@Test
+	void loadProperties() {
+		assertThat(this.environment.getProperty("spring.bar")).isEqualTo("bar");
+		assertThat(this.environment.getProperty("spring.foo")).isEqualTo("baz");
+		assertThat(this.environment.getProperty("spring.buzz")).isEqualTo("fazz");
+		assertThat(this.environment.getProperty("spring.boot")).isEqualTo("boot");
+		assertThat(this.environment.getProperty("key")).isEqualTo("value");
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	static class Config {
+
+	}
+
+}