Modify SpringApplication Environment rather than setting it

Update `SpringBootContextLoader` so that when possible the
`SpringApplication` remains in control of creating the `Environment`
instance.

Prior to this commit, we would always create the `Environment` in the
`SpringBootContextLoader` and then call `setEnvironment` on the
`SpringApplication`. This meant that the `ApplicationEnvironment`
classes were not used and that `isCustomEnvironment` was set to `true`
so no conversion was applied.

With the updated code, an `ApplicationListener` is used to mutate the
`Environment` instance and add the required test property sources.

Fixes gh-29169

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

@@ -18,12 +18,15 @@
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 import org.springframework.beans.BeanUtils;
 import org.springframework.boot.ApplicationContextFactory;
+import org.springframework.boot.DefaultPropertiesPropertySource;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.WebApplicationType;
+import org.springframework.boot.context.event.ApplicationEnvironmentPreparedEvent;
 import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
 import org.springframework.boot.test.mock.web.SpringBootMockServletContext;
 import org.springframework.boot.test.util.TestPropertyValues;
@@ -32,14 +35,18 @@
 import org.springframework.boot.web.servlet.support.ServletContextApplicationContextInitializer;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.ApplicationListener;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.Ordered;
+import org.springframework.core.PriorityOrdered;
 import org.springframework.core.SpringVersion;
 import org.springframework.core.annotation.MergedAnnotations;
 import org.springframework.core.annotation.MergedAnnotations.SearchStrategy;
 import org.springframework.core.annotation.Order;
+import org.springframework.core.env.CommandLinePropertySource;
 import org.springframework.core.env.ConfigurableEnvironment;
-import org.springframework.core.env.Environment;
+import org.springframework.core.env.MutablePropertySources;
+import org.springframework.core.env.PropertySource;
 import org.springframework.core.env.StandardEnvironment;
 import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.core.io.ResourceLoader;
@@ -53,6 +60,7 @@
 import org.springframework.test.context.web.WebMergedContextConfiguration;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.web.context.support.GenericWebApplicationContext;
 
@@ -81,6 +89,9 @@
  */
 public class SpringBootContextLoader extends AbstractContextLoader {
 
+	private static final String[] PRIORITY_PROPERTY_SOURCES = { "configurationProperties",
+			DefaultPropertiesPropertySource.NAME, CommandLinePropertySource.COMMAND_LINE_PROPERTY_SOURCE_NAME };
+
 	@Override
 	public ApplicationContext loadContext(MergedContextConfiguration config) throws Exception {
 		Class<?>[] configClasses = config.getClasses();
@@ -111,23 +122,49 @@ else if (config instanceof ReactiveWebMergedContextConfiguration) {
 			application.setWebApplicationType(WebApplicationType.NONE);
 		}
 		application.setInitializers(initializers);
-		ConfigurableEnvironment environment = getEnvironment();
-		setActiveProfiles(environment, config.getActiveProfiles());
+		boolean customEnvironent = ReflectionUtils.findMethod(getClass(), "getEnvironment")
+				.getDeclaringClass() != SpringBootContextLoader.class;
+		if (customEnvironent) {
+			ConfigurableEnvironment environment = getEnvironment();
+			prepareEnvironment(config, application, environment, false);
+			application.setEnvironment(environment);
+		}
+		else {
+			application.addListeners(new PrepareEnvironmentListener(config));
+		}
+		String[] args = SpringBootTestArgs.get(config.getContextCustomizers());
+		return application.run(args);
+	}
+
+	private void prepareEnvironment(MergedContextConfiguration config, SpringApplication application,
+			ConfigurableEnvironment environment, boolean applicationEnvironment) {
+		MutablePropertySources propertySources = environment.getPropertySources();
+		List<PropertySource<?>> priorityPropertySources = new ArrayList<>();
+		if (applicationEnvironment) {
+			for (String priorityPropertySourceName : PRIORITY_PROPERTY_SOURCES) {
+				PropertySource<?> priorityPropertySource = propertySources.get(priorityPropertySourceName);
+				if (priorityPropertySource != null) {
+					priorityPropertySources.add(priorityPropertySource);
+					propertySources.remove(priorityPropertySourceName);
+				}
+			}
+		}
+		setActiveProfiles(environment, config.getActiveProfiles(), applicationEnvironment);
 		ResourceLoader resourceLoader = (application.getResourceLoader() != null) ? application.getResourceLoader()
 				: new DefaultResourceLoader(null);
 		TestPropertySourceUtils.addPropertiesFilesToEnvironment(environment, resourceLoader,
 				config.getPropertySourceLocations());
 		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(environment, getInlinedProperties(config));
-		application.setEnvironment(environment);
-		String[] args = SpringBootTestArgs.get(config.getContextCustomizers());
-		return application.run(args);
+		Collections.reverse(priorityPropertySources);
+		priorityPropertySources.forEach(propertySources::addFirst);
 	}
 
-	private void setActiveProfiles(ConfigurableEnvironment environment, String[] profiles) {
+	private void setActiveProfiles(ConfigurableEnvironment environment, String[] profiles,
+			boolean applicationEnvironment) {
 		if (ObjectUtils.isEmpty(profiles)) {
 			return;
 		}
-		if (!(environment instanceof TestEnvironment)) {
+		if (!applicationEnvironment) {
 			environment.setActiveProfiles(profiles);
 		}
 		String[] pairs = new String[profiles.length];
@@ -152,7 +189,7 @@ protected SpringApplication getSpringApplication() {
 	 * @return a {@link ConfigurableEnvironment} instance
 	 */
 	protected ConfigurableEnvironment getEnvironment() {
-		return new TestEnvironment();
+		return new StandardEnvironment();
 	}
 
 	protected String[] getInlinedProperties(MergedContextConfiguration config) {
@@ -304,19 +341,25 @@ public void initialize(ConfigurableApplicationContext applicationContext) {
 	}
 
 	/**
-	 * Side-effect free {@link Environment} that doesn't set profiles directly from
-	 * properties.
+	 * {@link ApplicationListener} used to prepare the application created environment.
 	 */
-	static class TestEnvironment extends StandardEnvironment {
+	private class PrepareEnvironmentListener
+			implements ApplicationListener<ApplicationEnvironmentPreparedEvent>, PriorityOrdered {
+
+		private final MergedContextConfiguration config;
+
+		PrepareEnvironmentListener(MergedContextConfiguration config) {
+			this.config = config;
+		}
 
 		@Override
-		protected String doGetActiveProfilesProperty() {
-			return null;
+		public int getOrder() {
+			return Ordered.HIGHEST_PRECEDENCE;
 		}
 
 		@Override
-		protected String doGetDefaultProfilesProperty() {
-			return null;
+		public void onApplicationEvent(ApplicationEnvironmentPreparedEvent event) {
+			prepareEnvironment(this.config, event.getSpringApplication(), event.getEnvironment(), true);
 		}
 
 	}

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

@@ -16,19 +16,24 @@
 
 package org.springframework.boot.test.context;
 
+import java.util.List;
 import java.util.Map;
+import java.util.stream.Collectors;
 
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.test.util.TestPropertyValues;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.env.PropertySource;
 import org.springframework.core.env.StandardEnvironment;
 import org.springframework.test.context.ActiveProfiles;
 import org.springframework.test.context.MergedContextConfiguration;
 import org.springframework.test.context.TestContext;
 import org.springframework.test.context.TestContextManager;
+import org.springframework.test.context.TestPropertySource;
 import org.springframework.test.context.support.TestPropertySourceUtils;
 import org.springframework.test.util.ReflectionTestUtils;
 
@@ -127,6 +132,20 @@ void testPropertyValuesShouldTakePrecedenceWhenInlinedPropertiesPresentAndProfil
 		assertThat(environment.getPropertySources().get("active-test-profiles")).isNotNull();
 	}
 
+	@Test
+	void propertySourceOrdering() throws Exception {
+		TestContext context = new ExposedTestContextManager(PropertySourceOrdering.class).getExposedTestContext();
+		ConfigurableEnvironment environment = (ConfigurableEnvironment) context.getApplicationContext()
+				.getEnvironment();
+		List<String> names = environment.getPropertySources().stream().map(PropertySource::getName)
+				.collect(Collectors.toList());
+		String last = names.remove(names.size() - 1);
+		assertThat(names).containsExactly("configurationProperties", "commandLineArgs", "Inlined Test Properties",
+				"servletConfigInitParams", "servletContextInitParams", "systemProperties", "systemEnvironment",
+				"random");
+		assertThat(last).startsWith("Config resource");
+	}
+
 	private String[] getActiveProfiles(Class<?> testClass) {
 		TestContext testContext = new ExposedTestContextManager(testClass).getExposedTestContext();
 		ApplicationContext applicationContext = testContext.getApplicationContext();
@@ -198,6 +217,12 @@ static class ActiveProfileWithInlinedProperties {
 
 	}
 
+	@SpringBootTest(classes = Config.class, args = "args", properties = "one=1")
+	@TestPropertySource(properties = "two=2")
+	static class PropertySourceOrdering {
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class Config {
 

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-profile/src/test/java/smoketest/profile/ActiveProfilesTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -21,6 +21,7 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.env.EnvironmentPostProcessor;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
 import org.springframework.core.env.Environment;
 import org.springframework.test.context.ActiveProfiles;
 
@@ -32,7 +33,7 @@
  *
  * @author Madhura Bhave
  */
-@SpringBootTest(properties = "enableEnvironmentPostProcessor=true") // gh-28530
+@SpringBootTest(webEnvironment = WebEnvironment.NONE, properties = "enableEnvironmentPostProcessor=true") // gh-28530
 @ActiveProfiles("hello")
 class ActiveProfilesTests {