Polish `EnvConfigData`

Rename classes to align with existing `SystemEnvironment...` classes
and extract common `FileExtensionHint` logic.

See gh-41609

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigDataResourceNotFoundException.java

@@ -116,7 +116,7 @@ public class ConfigDataResourceNotFoundException extends ConfigDataNotFoundExcep
 	 * @param pathToCheck the path to check
 	 */
 	public static void throwIfDoesNotExist(ConfigDataResource resource, Path pathToCheck) {
-		throwIfDoesNotExist(resource, Files.exists(pathToCheck));
+		throwIfNot(resource, Files.exists(pathToCheck));
 	}
 
 	/**
@@ -126,7 +126,7 @@ public class ConfigDataResourceNotFoundException extends ConfigDataNotFoundExcep
 	 * @param fileToCheck the file to check
 	 */
 	public static void throwIfDoesNotExist(ConfigDataResource resource, File fileToCheck) {
-		throwIfDoesNotExist(resource, fileToCheck.exists());
+		throwIfNot(resource, fileToCheck.exists());
 	}
 
 	/**
@@ -136,11 +136,11 @@ public class ConfigDataResourceNotFoundException extends ConfigDataNotFoundExcep
 	 * @param resourceToCheck the resource to check
 	 */
 	public static void throwIfDoesNotExist(ConfigDataResource resource, Resource resourceToCheck) {
-		throwIfDoesNotExist(resource, resourceToCheck.exists());
+		throwIfNot(resource, resourceToCheck.exists());
 	}
 
-	private static void throwIfDoesNotExist(ConfigDataResource resource, boolean exists) {
-		if (!exists) {
+	private static void throwIfNot(ConfigDataResource resource, boolean check) {
+		if (!check) {
 			throw new ConfigDataResourceNotFoundException(resource);
 		}
 	}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/EnvConfigDataLoader.java

@@ -1,58 +0,0 @@
-/*
- * Copyright 2012-2025 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.context.config;
-
-import java.io.IOException;
-import java.nio.charset.StandardCharsets;
-import java.util.function.Function;
-
-import org.springframework.core.io.ByteArrayResource;
-
-/**
- * {@link ConfigDataLoader} to load data from environment variables.
- *
- * @author Moritz Halbritter
- */
-class EnvConfigDataLoader implements ConfigDataLoader<EnvConfigDataResource> {
-
-	private final Function<String, String> readEnvVariable;
-
-	EnvConfigDataLoader() {
-		this.readEnvVariable = System::getenv;
-	}
-
-	EnvConfigDataLoader(Function<String, String> readEnvVariable) {
-		this.readEnvVariable = readEnvVariable;
-	}
-
-	@Override
-	public ConfigData load(ConfigDataLoaderContext context, EnvConfigDataResource resource)
-			throws IOException, ConfigDataResourceNotFoundException {
-		String content = this.readEnvVariable.apply(resource.getVariableName());
-		if (content == null) {
-			throw new ConfigDataResourceNotFoundException(resource);
-		}
-		String name = String.format("Environment variable '%s' via location '%s'", resource.getVariableName(),
-				resource.getLocation());
-		return new ConfigData(resource.getLoader().load(name, createResource(content)));
-	}
-
-	private ByteArrayResource createResource(String content) {
-		return new ByteArrayResource(content.getBytes(StandardCharsets.UTF_8));
-	}
-
-}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/EnvConfigDataResource.java

@@ -1,75 +0,0 @@
-/*
- * Copyright 2012-2025 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.context.config;
-
-import java.util.Objects;
-
-import org.springframework.boot.env.PropertySourceLoader;
-
-/**
- * {@link ConfigDataResource} used by {@link EnvConfigDataLoader}.
- *
- * @author Moritz Halbritter
- */
-class EnvConfigDataResource extends ConfigDataResource {
-
-	private final ConfigDataLocation location;
-
-	private final String variableName;
-
-	private final PropertySourceLoader loader;
-
-	EnvConfigDataResource(ConfigDataLocation location, String variableName, PropertySourceLoader loader) {
-		super(location.isOptional());
-		this.location = location;
-		this.variableName = variableName;
-		this.loader = loader;
-	}
-
-	ConfigDataLocation getLocation() {
-		return this.location;
-	}
-
-	String getVariableName() {
-		return this.variableName;
-	}
-
-	PropertySourceLoader getLoader() {
-		return this.loader;
-	}
-
-	@Override
-	public boolean equals(Object o) {
-		if (o == null || getClass() != o.getClass()) {
-			return false;
-		}
-		EnvConfigDataResource that = (EnvConfigDataResource) o;
-		return Objects.equals(this.location, that.location) && Objects.equals(this.variableName, that.variableName)
-				&& Objects.equals(this.loader, that.loader);
-	}
-
-	@Override
-	public int hashCode() {
-		return Objects.hash(this.location, this.variableName, this.loader);
-	}
-
-	@Override
-	public String toString() {
-		return "env variable [" + this.variableName + "]";
-	}
-
-}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/FileExtensionHint.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2012-2025 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.context.config;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * User provided hint for an otherwise missing file extension.
+ *
+ * @author Phillip Webb
+ */
+final class FileExtensionHint {
+
+	private static final Pattern PATTERN = Pattern.compile("^(.*)\\[(\\.\\w+)](?!\\[)$");
+
+	private static final FileExtensionHint NONE = new FileExtensionHint(null);
+
+	private final Matcher matcher;
+
+	private FileExtensionHint(Matcher matcher) {
+		this.matcher = matcher;
+	}
+
+	/**
+	 * Return {@code true} if the hint is present.
+	 * @return if the hint is present
+	 */
+	boolean isPresent() {
+		return this.matcher != null;
+	}
+
+	/**
+	 * Return the extension from the hint or return the parameter if the hint is not
+	 * {@link #isPresent() present}.
+	 * @param extension the fallback extension
+	 * @return the extension either from the hint or fallback
+	 */
+	String orElse(String extension) {
+		return (this.matcher != null) ? toString() : extension;
+	}
+
+	@Override
+	public String toString() {
+		return (this.matcher != null) ? this.matcher.group(2) : "";
+	}
+
+	/**
+	 * Return the {@link FileExtensionHint} from the given value.
+	 * @param value the source value
+	 * @return the {@link FileExtensionHint} (never {@code null})
+	 */
+	static FileExtensionHint from(String value) {
+		Matcher matcher = PATTERN.matcher(value);
+		return (matcher.matches()) ? new FileExtensionHint(matcher) : NONE;
+	}
+
+	/**
+	 * Remove any hint from the given value.
+	 * @param value the source value
+	 * @return the value without any hint
+	 */
+	static String removeFrom(String value) {
+		Matcher matcher = PATTERN.matcher(value);
+		return (matcher.matches()) ? matcher.group(1) : value;
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/StandardConfigDataLocationResolver.java

@@ -26,7 +26,6 @@ import java.util.Deque;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
-import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
@@ -68,8 +67,6 @@ public class StandardConfigDataLocationResolver
 
 	private static final Pattern URL_PREFIX = Pattern.compile("^([a-zA-Z][a-zA-Z0-9*]*?:)(.*$)");
 
-	private static final Pattern EXTENSION_HINT_PATTERN = Pattern.compile("^(.*)\\[(\\.\\w+)](?!\\[)$");
-
 	private static final String NO_PROFILE = null;
 
 	private final Log logger;
@@ -238,17 +235,16 @@ public class StandardConfigDataLocationResolver
 
 	private Set<StandardConfigDataReference> getReferencesForFile(ConfigDataLocation configDataLocation, String file,
 			String profile) {
-		Matcher extensionHintMatcher = EXTENSION_HINT_PATTERN.matcher(file);
-		boolean extensionHintLocation = extensionHintMatcher.matches();
-		if (extensionHintLocation) {
-			file = extensionHintMatcher.group(1) + extensionHintMatcher.group(2);
+		FileExtensionHint fileExtensionHint = FileExtensionHint.from(file);
+		if (fileExtensionHint.isPresent()) {
+			file = FileExtensionHint.removeFrom(file) + fileExtensionHint;
 		}
 		for (PropertySourceLoader propertySourceLoader : this.propertySourceLoaders) {
-			String extension = getLoadableFileExtension(propertySourceLoader, file);
-			if (extension != null) {
-				String root = file.substring(0, file.length() - extension.length() - 1);
+			String fileExtension = getLoadableFileExtension(propertySourceLoader, file);
+			if (fileExtension != null) {
+				String root = file.substring(0, file.length() - fileExtension.length() - 1);
 				StandardConfigDataReference reference = new StandardConfigDataReference(configDataLocation, null, root,
-						profile, (!extensionHintLocation) ? extension : null, propertySourceLoader);
+						profile, (!fileExtensionHint.isPresent()) ? fileExtension : null, propertySourceLoader);
 				return Collections.singleton(reference);
 			}
 		}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/SystemEnvironmentConfigDataLoader.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2012-2025 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.context.config;
+
+import java.io.IOException;
+import java.util.List;
+
+import org.springframework.core.env.PropertySource;
+
+/**
+ * {@link ConfigDataLoader} to load data from system environment variables.
+ *
+ * @author Moritz Halbritter
+ */
+class SystemEnvironmentConfigDataLoader implements ConfigDataLoader<SystemEnvironmentConfigDataResource> {
+
+	@Override
+	public ConfigData load(ConfigDataLoaderContext context, SystemEnvironmentConfigDataResource resource)
+			throws IOException, ConfigDataResourceNotFoundException {
+		List<PropertySource<?>> loaded = resource.load();
+		if (loaded == null) {
+			throw new ConfigDataResourceNotFoundException(resource);
+		}
+		return new ConfigData(loaded);
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/SystemEnvironmentConfigDataLocationResolver.java

@@ -19,8 +19,6 @@ package org.springframework.boot.context.config;
 import java.util.Collections;
 import java.util.List;
 import java.util.function.Function;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
 import org.springframework.boot.env.PropertySourceLoader;
 import org.springframework.core.io.support.SpringFactoriesLoader;
@@ -29,27 +27,28 @@ import org.springframework.core.io.support.SpringFactoriesLoader;
  * {@link ConfigDataLocationResolver} to resolve {@code env:} locations.
  *
  * @author Moritz Halbritter
+ * @author Phillip Webb
  */
-class EnvConfigDataLocationResolver implements ConfigDataLocationResolver<EnvConfigDataResource> {
+class SystemEnvironmentConfigDataLocationResolver
+		implements ConfigDataLocationResolver<SystemEnvironmentConfigDataResource> {
 
 	private static final String PREFIX = "env:";
 
-	private static final Pattern EXTENSION_HINT_PATTERN = Pattern.compile("^(.*)\\[(\\.\\w+)](?!\\[)$");
-
 	private static final String DEFAULT_EXTENSION = ".properties";
 
 	private final List<PropertySourceLoader> loaders;
 
-	private final Function<String, String> readEnvVariable;
+	private final Function<String, String> environment;
 
-	EnvConfigDataLocationResolver() {
+	SystemEnvironmentConfigDataLocationResolver() {
 		this.loaders = SpringFactoriesLoader.loadFactories(PropertySourceLoader.class, getClass().getClassLoader());
-		this.readEnvVariable = System::getenv;
+		this.environment = System::getenv;
 	}
 
-	EnvConfigDataLocationResolver(List<PropertySourceLoader> loaders, Function<String, String> readEnvVariable) {
+	SystemEnvironmentConfigDataLocationResolver(List<PropertySourceLoader> loaders,
+			Function<String, String> environment) {
 		this.loaders = loaders;
-		this.readEnvVariable = readEnvVariable;
+		this.environment = environment;
 	}
 
 	@Override
@@ -58,15 +57,15 @@ class EnvConfigDataLocationResolver implements ConfigDataLocationResolver<EnvCon
 	}
 
 	@Override
-	public List<EnvConfigDataResource> resolve(ConfigDataLocationResolverContext context, ConfigDataLocation location)
+	public List<SystemEnvironmentConfigDataResource> resolve(ConfigDataLocationResolverContext context,
+			ConfigDataLocation location)
 			throws ConfigDataLocationNotFoundException, ConfigDataResourceNotFoundException {
 		String value = location.getNonPrefixedValue(PREFIX);
-		Matcher matcher = EXTENSION_HINT_PATTERN.matcher(value);
-		String extension = getExtension(matcher);
-		String variableName = getVariableName(matcher, value);
-		PropertySourceLoader loader = getLoader(extension);
+		FileExtensionHint fileExtensionHint = FileExtensionHint.from(value);
+		String variableName = FileExtensionHint.removeFrom(value);
+		PropertySourceLoader loader = getLoader(fileExtensionHint.orElse(DEFAULT_EXTENSION));
 		if (hasEnvVariable(variableName)) {
-			return List.of(new EnvConfigDataResource(location, variableName, loader));
+			return List.of(new SystemEnvironmentConfigDataResource(variableName, loader, this.environment));
 		}
 		if (location.isOptional()) {
 			return Collections.emptyList();
@@ -76,12 +75,7 @@ class EnvConfigDataLocationResolver implements ConfigDataLocationResolver<EnvCon
 	}
 
 	private PropertySourceLoader getLoader(String extension) {
-		if (extension == null) {
-			extension = DEFAULT_EXTENSION;
-		}
-		if (extension.startsWith(".")) {
-			extension = extension.substring(1);
-		}
+		extension = (!extension.startsWith(".")) ? extension : extension.substring(1);
 		for (PropertySourceLoader loader : this.loaders) {
 			for (String supportedExtension : loader.getFileExtensions()) {
 				if (supportedExtension.equalsIgnoreCase(extension)) {
@@ -94,21 +88,7 @@ class EnvConfigDataLocationResolver implements ConfigDataLocationResolver<EnvCon
 	}
 
 	private boolean hasEnvVariable(String variableName) {
-		return this.readEnvVariable.apply(variableName) != null;
-	}
-
-	private String getVariableName(Matcher matcher, String value) {
-		if (matcher.matches()) {
-			return matcher.group(1);
-		}
-		return value;
-	}
-
-	private String getExtension(Matcher matcher) {
-		if (matcher.matches()) {
-			return matcher.group(2);
-		}
-		return null;
+		return this.environment.apply(variableName) != null;
 	}
 
 }

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/SystemEnvironmentConfigDataResource.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2012-2025 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.context.config;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import java.util.Objects;
+import java.util.function.Function;
+
+import org.springframework.boot.env.PropertySourceLoader;
+import org.springframework.core.env.PropertySource;
+import org.springframework.core.io.ByteArrayResource;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.StringUtils;
+
+/**
+ * {@link ConfigDataResource} used by {@link SystemEnvironmentConfigDataLoader}.
+ *
+ * @author Moritz Halbritter
+ */
+class SystemEnvironmentConfigDataResource extends ConfigDataResource {
+
+	private final String variableName;
+
+	private final PropertySourceLoader loader;
+
+	private final Function<String, String> environment;
+
+	SystemEnvironmentConfigDataResource(String variableName, PropertySourceLoader loader,
+			Function<String, String> environment) {
+		this.variableName = variableName;
+		this.loader = loader;
+		this.environment = environment;
+	}
+
+	String getVariableName() {
+		return this.variableName;
+	}
+
+	PropertySourceLoader getLoader() {
+		return this.loader;
+	}
+
+	List<PropertySource<?>> load() throws IOException {
+		String content = this.environment.apply(this.variableName);
+		return (content != null) ? this.loader.load(StringUtils.capitalize(toString()), asResource(content)) : null;
+	}
+
+	private ByteArrayResource asResource(String content) {
+		return new ByteArrayResource(content.getBytes(StandardCharsets.UTF_8));
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) {
+			return true;
+		}
+		if (obj == null || getClass() != obj.getClass()) {
+			return false;
+		}
+		SystemEnvironmentConfigDataResource other = (SystemEnvironmentConfigDataResource) obj;
+		return Objects.equals(this.loader.getClass(), other.loader.getClass())
+				&& Objects.equals(this.variableName, other.variableName);
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(this.variableName, this.loader.getClass());
+	}
+
+	@Override
+	public String toString() {
+		return "system envionement variable [" + this.variableName + "] content loaded using "
+				+ ClassUtils.getShortName(this.loader.getClass());
+	}
+
+}

spring-boot-project/spring-boot/src/main/resources/META-INF/spring.factories

@@ -12,14 +12,14 @@ org.springframework.boot.env.YamlPropertySourceLoader
 # ConfigData Location Resolvers
 org.springframework.boot.context.config.ConfigDataLocationResolver=\
 org.springframework.boot.context.config.ConfigTreeConfigDataLocationResolver,\
-org.springframework.boot.context.config.EnvConfigDataLocationResolver,\
-org.springframework.boot.context.config.StandardConfigDataLocationResolver
+org.springframework.boot.context.config.StandardConfigDataLocationResolver,\
+org.springframework.boot.context.config.SystemEnvironmentConfigDataLocationResolver
 
 # ConfigData Loaders
 org.springframework.boot.context.config.ConfigDataLoader=\
 org.springframework.boot.context.config.ConfigTreeConfigDataLoader,\
-org.springframework.boot.context.config.EnvConfigDataLoader,\
-org.springframework.boot.context.config.StandardConfigDataLoader
+org.springframework.boot.context.config.StandardConfigDataLoader,\
+org.springframework.boot.context.config.SystemEnvironmentConfigDataLoader
 
 # Application Context Factories
 org.springframework.boot.ApplicationContextFactory=\

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

@@ -1,65 +0,0 @@
-/*
- * Copyright 2012-2025 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.context.config;
-
-import org.junit.jupiter.api.Test;
-
-import org.springframework.boot.env.PropertiesPropertySourceLoader;
-import org.springframework.boot.env.PropertySourceLoader;
-import org.springframework.boot.env.YamlPropertySourceLoader;
-
-import static org.assertj.core.api.Assertions.assertThat;
-
-/**
- * Tests for {@link EnvConfigDataResource}.
- *
- * @author Moritz Halbritter
- */
-class EnvConfigDataResourceTests {
-
-	private final YamlPropertySourceLoader yamlPropertySourceLoader = new YamlPropertySourceLoader();
-
-	private final PropertiesPropertySourceLoader propertiesPropertySourceLoader = new PropertiesPropertySourceLoader();
-
-	@Test
-	void shouldHaveEqualsAndHashcode() {
-		EnvConfigDataResource var1 = createResource("VAR1");
-		EnvConfigDataResource var2 = createResource("VAR2");
-		EnvConfigDataResource var3 = createResource("VAR1", this.yamlPropertySourceLoader);
-		EnvConfigDataResource var4 = createResource("VAR1");
-		assertThat(var1).isNotEqualTo(var2);
-		assertThat(var1).isNotEqualTo(var3);
-		assertThat(var1).isEqualTo(var4);
-		assertThat(var1).hasSameHashCodeAs(var4);
-	}
-
-	@Test
-	void shouldHaveToString() {
-		EnvConfigDataResource resource = createResource("VAR1");
-		assertThat(resource).hasToString("env variable [VAR1]");
-	}
-
-	private EnvConfigDataResource createResource(String variableName) {
-		return createResource(variableName, this.propertiesPropertySourceLoader);
-	}
-
-	private EnvConfigDataResource createResource(String variableName, PropertySourceLoader propertySourceLoader) {
-		return new EnvConfigDataResource(ConfigDataLocation.of("env:" + variableName), variableName,
-				propertySourceLoader);
-	}
-
-}

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

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2012-2025 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.context.config;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link FileExtensionHint}.
+ *
+ * @author Phillip Webb
+ */
+class FileExtensionHintTests {
+
+	@Test
+	void isPresentWhenHasHint() {
+		assertThat(FileExtensionHint.from("foo[.bar]").isPresent()).isTrue();
+	}
+
+	@Test
+	void isPresentWhenHasNoHint() {
+		assertThat(FileExtensionHint.from("foo").isPresent()).isFalse();
+		assertThat(FileExtensionHint.from("foo[bar]").isPresent()).isFalse();
+		assertThat(FileExtensionHint.from("foo[.b[ar]").isPresent()).isFalse();
+	}
+
+	@Test
+	void orElseWhenHasHint() {
+		assertThat(FileExtensionHint.from("foo[.bar]").orElse(".txt")).isEqualTo(".bar");
+	}
+
+	@Test
+	void orElseWhenHasNoHint() {
+		assertThat(FileExtensionHint.from("foo").orElse(".txt")).isEqualTo(".txt");
+	}
+
+	@Test
+	void toStringWhenHasHintReturnsDotExtension() {
+		assertThat(FileExtensionHint.from("foo[.bar]")).hasToString(".bar");
+	}
+
+	@Test
+	void toStringWhenHasNoHintReturnsEmpty() {
+		assertThat(FileExtensionHint.from("foo")).hasToString("");
+	}
+
+	@Test
+	void removeFromWhenHasHint() {
+		assertThat(FileExtensionHint.removeFrom("foo[.bar]")).isEqualTo("foo");
+	}
+
+	@Test
+	void removeFromWhenHasNoHint() {
+		assertThat(FileExtensionHint.removeFrom("foo[bar]")).isEqualTo("foo[bar]");
+	}
+
+}

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

@@ -31,28 +31,28 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.mockito.Mockito.mock;
 
 /**
- * Tests for {@link EnvConfigDataLoader}.
+ * Tests for {@link SystemEnvironmentConfigDataLoader}.
  *
  * @author Moritz Halbritter
  */
-class EnvConfigDataLoaderTests {
+class SystemEnvironmentConfigDataLoaderTests {
 
 	private ConfigDataLoaderContext context;
 
-	private Map<String, String> envVariables;
+	private Map<String, String> environment;
 
-	private EnvConfigDataLoader loader;
+	private SystemEnvironmentConfigDataLoader loader;
 
 	@BeforeEach
 	void setUp() {
 		this.context = mock(ConfigDataLoaderContext.class);
-		this.envVariables = new HashMap<>();
-		this.loader = new EnvConfigDataLoader(this.envVariables::get);
+		this.environment = new HashMap<>();
+		this.loader = new SystemEnvironmentConfigDataLoader();
 	}
 
 	@Test
-	void shouldLoadFromVariable() throws IOException {
-		this.envVariables.put("VAR1", "key1=value1");
+	void loadLoadsConfigData() throws IOException {
+		this.environment.put("VAR1", "key1=value1");
 		ConfigData data = this.loader.load(this.context, createResource("VAR1"));
 		assertThat(data.getPropertySources()).hasSize(1);
 		PropertySource<?> propertySource = data.getPropertySources().get(0);
@@ -60,15 +60,16 @@ class EnvConfigDataLoaderTests {
 	}
 
 	@Test
-	void shouldFailIfVariableIsNotSet() {
+	void loadWhenNoContentThrowsException() {
 		assertThatExceptionOfType(ConfigDataResourceNotFoundException.class)
 			.isThrownBy(() -> this.loader.load(this.context, createResource("VAR1")))
-			.withMessage("Config data resource 'env variable [VAR1]' cannot be found");
+			.withMessage("Config data resource 'system envionement variable [VAR1] content "
+					+ "loaded using PropertiesPropertySourceLoader' cannot be found");
 	}
 
-	private static EnvConfigDataResource createResource(String variableName) {
-		return new EnvConfigDataResource(ConfigDataLocation.of("env:" + variableName), variableName,
-				new PropertiesPropertySourceLoader());
+	private SystemEnvironmentConfigDataResource createResource(String variableName) {
+		return new SystemEnvironmentConfigDataResource(variableName, new PropertiesPropertySourceLoader(),
+				this.environment::get);
 	}
 
 }

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

@@ -32,24 +32,24 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 import static org.mockito.Mockito.mock;
 
 /**
- * Tests for {@link EnvConfigDataLocationResolver}.
+ * Tests for {@link SystemEnvironmentConfigDataLocationResolver}.
  *
  * @author Moritz Halbritter
  */
-class EnvConfigDataLocationResolverTests {
+class SystemEnvironmentConfigDataLocationResolverTests {
 
-	private EnvConfigDataLocationResolver resolver;
+	private SystemEnvironmentConfigDataLocationResolver resolver;
 
-	private Map<String, String> envVariables;
+	private Map<String, String> environment;
 
 	private ConfigDataLocationResolverContext context;
 
 	@BeforeEach
 	void setUp() {
 		this.context = mock(ConfigDataLocationResolverContext.class);
-		this.envVariables = new HashMap<>();
-		this.resolver = new EnvConfigDataLocationResolver(
-				List.of(new PropertiesPropertySourceLoader(), new YamlPropertySourceLoader()), this.envVariables::get);
+		this.environment = new HashMap<>();
+		this.resolver = new SystemEnvironmentConfigDataLocationResolver(
+				List.of(new PropertiesPropertySourceLoader(), new YamlPropertySourceLoader()), this.environment::get);
 	}
 
 	@Test
@@ -60,69 +60,65 @@ class EnvConfigDataLocationResolverTests {
 	}
 
 	@Test
-	void shouldResolve() {
-		this.envVariables.put("VAR1", "VALUE1");
+	void resolveResolves() {
+		this.environment.put("VAR1", "VALUE1");
 		ConfigDataLocation location = ConfigDataLocation.of("env:VAR1");
-		List<EnvConfigDataResource> resolved = this.resolver.resolve(this.context, location);
+		List<SystemEnvironmentConfigDataResource> resolved = this.resolver.resolve(this.context, location);
 		assertThat(resolved).hasSize(1);
-		EnvConfigDataResource resource = resolved.get(0);
-		assertThat(resource.getLocation()).isEqualTo(location);
+		SystemEnvironmentConfigDataResource resource = resolved.get(0);
 		assertThat(resource.getVariableName()).isEqualTo("VAR1");
 		assertThat(resource.getLoader()).isInstanceOf(PropertiesPropertySourceLoader.class);
 	}
 
 	@Test
-	void shouldResolveOptional() {
-		this.envVariables.put("VAR1", "VALUE1");
-		ConfigDataLocation location = ConfigDataLocation.of("optional:env:VAR1");
-		List<EnvConfigDataResource> resolved = this.resolver.resolve(this.context, location);
-		assertThat(resolved).hasSize(1);
-		EnvConfigDataResource resource = resolved.get(0);
-		assertThat(resource.getLocation()).isEqualTo(location);
-		assertThat(resource.getVariableName()).isEqualTo("VAR1");
-		assertThat(resource.getLoader()).isInstanceOf(PropertiesPropertySourceLoader.class);
-	}
-
-	@Test
-	void shouldResolveOptionalIfVariableIsNotSet() {
-		ConfigDataLocation location = ConfigDataLocation.of("optional:env:VAR1");
-		List<EnvConfigDataResource> resolved = this.resolver.resolve(this.context, location);
-		assertThat(resolved).isEmpty();
-	}
-
-	@Test
-	void shouldResolveWithPropertiesExtension() {
-		this.envVariables.put("VAR1", "VALUE1");
-		ConfigDataLocation location = ConfigDataLocation.of("env:VAR1[.properties]");
-		List<EnvConfigDataResource> resolved = this.resolver.resolve(this.context, location);
-		assertThat(resolved).hasSize(1);
-		EnvConfigDataResource resource = resolved.get(0);
-		assertThat(resource.getLocation()).isEqualTo(location);
-		assertThat(resource.getVariableName()).isEqualTo("VAR1");
-		assertThat(resource.getLoader()).isInstanceOf(PropertiesPropertySourceLoader.class);
-	}
-
-	@Test
-	void shouldResolveWithYamlExtension() {
-		this.envVariables.put("VAR1", "VALUE1");
-		ConfigDataLocation location = ConfigDataLocation.of("env:VAR1[.yaml]");
-		List<EnvConfigDataResource> resolved = this.resolver.resolve(this.context, location);
-		assertThat(resolved).hasSize(1);
-		EnvConfigDataResource resource = resolved.get(0);
-		assertThat(resource.getLocation()).isEqualTo(location);
-		assertThat(resource.getVariableName()).isEqualTo("VAR1");
-		assertThat(resource.getLoader()).isInstanceOf(YamlPropertySourceLoader.class);
-	}
-
-	@Test
-	void shouldFailIfVariableIsNotSet() {
+	void resolveWhenHasNoVariableThrowsException() {
 		assertThatExceptionOfType(ConfigDataLocationNotFoundException.class)
 			.isThrownBy(() -> this.resolver.resolve(this.context, ConfigDataLocation.of("env:VAR1")))
 			.withMessage("Environment variable 'VAR1' is not set");
 	}
 
 	@Test
-	void shouldFailIfUnknownExtensionIsGiven() {
+	void resolveWhenOptionalAndHasVariableResolves() {
+		this.environment.put("VAR1", "VALUE1");
+		ConfigDataLocation location = ConfigDataLocation.of("optional:env:VAR1");
+		List<SystemEnvironmentConfigDataResource> resolved = this.resolver.resolve(this.context, location);
+		assertThat(resolved).hasSize(1);
+		SystemEnvironmentConfigDataResource resource = resolved.get(0);
+		assertThat(resource.getVariableName()).isEqualTo("VAR1");
+		assertThat(resource.getLoader()).isInstanceOf(PropertiesPropertySourceLoader.class);
+	}
+
+	@Test
+	void resolveWhenOptionalAndHasNoVariableResolvesEmpty() {
+		ConfigDataLocation location = ConfigDataLocation.of("optional:env:VAR1");
+		List<SystemEnvironmentConfigDataResource> resolved = this.resolver.resolve(this.context, location);
+		assertThat(resolved).isEmpty();
+	}
+
+	@Test
+	void resolveWhenHasPropertiesExtensionHintResolves() {
+		this.environment.put("VAR1", "VALUE1");
+		ConfigDataLocation location = ConfigDataLocation.of("env:VAR1[.properties]");
+		List<SystemEnvironmentConfigDataResource> resolved = this.resolver.resolve(this.context, location);
+		assertThat(resolved).hasSize(1);
+		SystemEnvironmentConfigDataResource resource = resolved.get(0);
+		assertThat(resource.getVariableName()).isEqualTo("VAR1");
+		assertThat(resource.getLoader()).isInstanceOf(PropertiesPropertySourceLoader.class);
+	}
+
+	@Test
+	void resolveWhenHasYamlExtensionHintResolves() {
+		this.environment.put("VAR1", "VALUE1");
+		ConfigDataLocation location = ConfigDataLocation.of("env:VAR1[.yaml]");
+		List<SystemEnvironmentConfigDataResource> resolved = this.resolver.resolve(this.context, location);
+		assertThat(resolved).hasSize(1);
+		SystemEnvironmentConfigDataResource resource = resolved.get(0);
+		assertThat(resource.getVariableName()).isEqualTo("VAR1");
+		assertThat(resource.getLoader()).isInstanceOf(YamlPropertySourceLoader.class);
+	}
+
+	@Test
+	void resolveWhenHasUnknownExtensionHintThrowsException() {
 		assertThatIllegalStateException()
 			.isThrownBy(() -> this.resolver.resolve(this.context, ConfigDataLocation.of("env:VAR1[.dummy]")))
 			.withMessage("File extension 'dummy' is not known to any PropertySourceLoader");

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

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2012-2025 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.context.config;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.env.PropertiesPropertySourceLoader;
+import org.springframework.boot.env.PropertySourceLoader;
+import org.springframework.boot.env.YamlPropertySourceLoader;
+import org.springframework.core.env.PropertySource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link SystemEnvironmentConfigDataResource}.
+ *
+ * @author Moritz Halbritter
+ */
+class SystemEnvironmentConfigDataResourceTests {
+
+	private Map<String, String> environment = new HashMap<>();
+
+	private final YamlPropertySourceLoader yamlLoader = new YamlPropertySourceLoader();
+
+	private final PropertiesPropertySourceLoader propertiesLoader = new PropertiesPropertySourceLoader();
+
+	@Test
+	void loadLoadsPropertySources() throws IOException {
+		this.environment.put("VAR1", "key1=value1");
+		List<PropertySource<?>> loaded = createResource("VAR1").load();
+		assertThat(loaded).hasSize(1);
+		assertThat(loaded.get(0).getProperty("key1")).isEqualTo("value1");
+	}
+
+	@Test
+	void loadWhenNoContentReturnsNull() throws IOException {
+		List<PropertySource<?>> loaded = createResource("VAR1").load();
+		assertThat(loaded).isNull();
+	}
+
+	@Test
+	void equalsAndHashcode() {
+		SystemEnvironmentConfigDataResource var1 = createResource("VAR1");
+		SystemEnvironmentConfigDataResource var2 = createResource("VAR2");
+		SystemEnvironmentConfigDataResource var3 = createResource("VAR1", this.yamlLoader);
+		SystemEnvironmentConfigDataResource var4 = createResource("VAR1");
+		assertThat(var1).isNotEqualTo(var2);
+		assertThat(var1).isNotEqualTo(var3);
+		assertThat(var1).isEqualTo(var4);
+		assertThat(var1).hasSameHashCodeAs(var4);
+	}
+
+	@Test
+	void toStringReturnsString() {
+		SystemEnvironmentConfigDataResource resource = createResource("VAR1");
+		assertThat(resource)
+			.hasToString("system envionement variable [VAR1] content loaded using PropertiesPropertySourceLoader");
+	}
+
+	private SystemEnvironmentConfigDataResource createResource(String variableName) {
+		return createResource(variableName, this.propertiesLoader);
+	}
+
+	private SystemEnvironmentConfigDataResource createResource(String variableName,
+			PropertySourceLoader propertySourceLoader) {
+		return new SystemEnvironmentConfigDataResource(variableName, propertySourceLoader, this.environment::get);
+	}
+
+}