Perform placeholder resolution in test env post processor

Fixes gh-15354

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/web/SpringBootTestRandomPortEnvironmentPostProcessor.java

@@ -19,7 +19,7 @@ import java.util.Objects;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.env.EnvironmentPostProcessor;
-import org.springframework.core.convert.ConversionService;
+import org.springframework.core.convert.ConversionFailedException;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.MapPropertySource;
 import org.springframework.core.env.PropertySource;
@@ -46,8 +46,7 @@ class SpringBootTestRandomPortEnvironmentPostProcessor
 			SpringApplication application) {
 		MapPropertySource source = (MapPropertySource) environment.getPropertySources()
 				.get(TestPropertySourceUtils.INLINED_PROPERTIES_PROPERTY_SOURCE_NAME);
-		if (source == null
-				|| isTestServerPortFixed(source, environment.getConversionService())
+		if (source == null || isTestServerPortFixed(source, environment)
 				|| isTestManagementPortConfigured(source)) {
 			return;
 		}
@@ -67,9 +66,9 @@ class SpringBootTestRandomPortEnvironmentPostProcessor
 	}
 
 	private boolean isTestServerPortFixed(MapPropertySource source,
-			ConversionService conversionService) {
-		return !Integer.valueOf(0).equals(
-				getPropertyAsInteger(source, SERVER_PORT_PROPERTY, conversionService));
+			ConfigurableEnvironment environment) {
+		return !Integer.valueOf(0)
+				.equals(getPropertyAsInteger(source, SERVER_PORT_PROPERTY, environment));
 	}
 
 	private boolean isTestManagementPortConfigured(PropertySource<?> source) {
@@ -81,13 +80,12 @@ class SpringBootTestRandomPortEnvironmentPostProcessor
 		return environment.getPropertySources().stream()
 				.filter((source) -> !source.getName().equals(
 						TestPropertySourceUtils.INLINED_PROPERTIES_PROPERTY_SOURCE_NAME))
-				.map((source) -> getPropertyAsInteger(source, property,
-						environment.getConversionService()))
+				.map((source) -> getPropertyAsInteger(source, property, environment))
 				.filter(Objects::nonNull).findFirst().orElse(defaultValue);
 	}
 
 	private Integer getPropertyAsInteger(PropertySource<?> source, String property,
-			ConversionService conversionService) {
+			ConfigurableEnvironment environment) {
 		Object value = source.getProperty(property);
 		if (value == null) {
 			return null;
@@ -95,7 +93,21 @@ class SpringBootTestRandomPortEnvironmentPostProcessor
 		if (ClassUtils.isAssignableValue(Integer.class, value)) {
 			return (Integer) value;
 		}
-		return conversionService.convert(value, Integer.class);
+		try {
+			return environment.getConversionService().convert(value, Integer.class);
+		}
+		catch (ConversionFailedException ex) {
+			if (ClassUtils.isAssignable(value.getClass(), String.class)) {
+				return getResolvedValueIfPossible(environment, (String) value);
+			}
+			throw ex;
+		}
+	}
+
+	private Integer getResolvedValueIfPossible(ConfigurableEnvironment environment,
+			String value) {
+		String resolvedValue = environment.resolveRequiredPlaceholders(value);
+		return environment.getConversionService().convert(resolvedValue, Integer.class);
 	}
 
 }

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/web/SpringBootTestRandomPortEnvironmentPostProcessorTests.java

@@ -28,6 +28,7 @@ import org.springframework.mock.env.MockEnvironment;
 import org.springframework.test.context.support.TestPropertySourceUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 
 /**
  * Tests for {@link SpringBootTestRandomPortEnvironmentPostProcessor}.
@@ -141,6 +142,56 @@ public class SpringBootTestRandomPortEnvironmentPostProcessorTests {
 		assertThat(this.environment.getProperty("management.server.port")).isEqualTo("0");
 	}
 
+	@Test
+	public void postProcessWhenManagementServerPortPlaceholderPresentShouldResolvePlaceholder() {
+		addTestPropertySource("0", null);
+		MapPropertySource testPropertySource = (MapPropertySource) this.propertySources
+				.get(TestPropertySourceUtils.INLINED_PROPERTIES_PROPERTY_SOURCE_NAME);
+		testPropertySource.getSource().put("port", "9090");
+		this.propertySources.addLast(new MapPropertySource("other",
+				Collections.singletonMap("management.server.port", "${port}")));
+		this.postProcessor.postProcessEnvironment(this.environment, null);
+		assertThat(this.environment.getProperty("server.port")).isEqualTo("0");
+		assertThat(this.environment.getProperty("management.server.port")).isEqualTo("0");
+	}
+
+	@Test
+	public void postProcessWhenManagementServerPortPlaceholderAbsentShouldFail() {
+		addTestPropertySource("0", null);
+		this.propertySources.addLast(new MapPropertySource("other",
+				Collections.singletonMap("management.server.port", "${port}")));
+		assertThatIllegalArgumentException().isThrownBy(
+				() -> this.postProcessor.postProcessEnvironment(this.environment, null))
+				.withMessage("Could not resolve placeholder 'port' in value \"${port}\"");
+	}
+
+	@Test
+	public void postProcessWhenServerPortPlaceholderPresentShouldResolvePlaceholder() {
+		addTestPropertySource("0", null);
+		MapPropertySource testPropertySource = (MapPropertySource) this.propertySources
+				.get(TestPropertySourceUtils.INLINED_PROPERTIES_PROPERTY_SOURCE_NAME);
+		testPropertySource.getSource().put("port", "8080");
+		Map<String, Object> source = new HashMap<>();
+		source.put("server.port", "${port}");
+		source.put("management.server.port", "9090");
+		this.propertySources.addLast(new MapPropertySource("other", source));
+		this.postProcessor.postProcessEnvironment(this.environment, null);
+		assertThat(this.environment.getProperty("server.port")).isEqualTo("0");
+		assertThat(this.environment.getProperty("management.server.port")).isEqualTo("0");
+	}
+
+	@Test
+	public void postProcessWhenServerPortPlaceholderAbsentShouldFail() {
+		addTestPropertySource("0", null);
+		Map<String, Object> source = new HashMap<>();
+		source.put("server.port", "${port}");
+		source.put("management.server.port", "9090");
+		this.propertySources.addLast(new MapPropertySource("other", source));
+		assertThatIllegalArgumentException().isThrownBy(
+				() -> this.postProcessor.postProcessEnvironment(this.environment, null))
+				.withMessage("Could not resolve placeholder 'port' in value \"${port}\"");
+	}
+
 	private void addTestPropertySource(String serverPort, String managementPort) {
 		Map<String, Object> source = new HashMap<>();
 		source.put("server.port", serverPort);