Improve testing of PropertyPlaceholderAutoConfiguration

Since Spring Framework 4.3.0.RC2, a default embedded value resolver
has been registered with the bean factory when one is not otherwise
configured. This meant that placeholders in `@Value` would be resolved
with or without PropertyPlaceholderAutoConfiguration defining a
PropertySourcesPlaceholderConfigurer bean. However, placeholders in
bean definitions would only be resolved if a
PropertySourcesPlaceholderConfigurer was defined.

This commit updates PropertyPlaceholderAutoConfigurationTests to align
with this change in Framework. We now test that placeholders are
resolved in `@Value` annotations with or without the auto-configuration
and that placeholders in bean definitions are only resolved with the
auto-configured.

Closes gh-22230

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -16,12 +16,14 @@
 
 package org.springframework.boot.autoconfigure.context;
 
-import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.annotation.Value;
-import org.springframework.boot.test.util.TestPropertyValues;
-import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.beans.factory.support.BeanDefinitionBuilder;
+import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
@@ -33,43 +35,75 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for {@link PropertyPlaceholderAutoConfiguration}.
  *
  * @author Dave Syer
+ * @author Andy Wilkinson
  */
 class PropertyPlaceholderAutoConfigurationTests {
 
-	private final AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner();
 
-	@AfterEach
-	void close() {
-		if (this.context != null) {
-			this.context.close();
-		}
+	@Test
+	void whenTheAutoConfigurationIsNotUsedThenBeanDefinitionPlaceholdersAreNotResolved() {
+		this.contextRunner.withPropertyValues("fruit:banana").withInitializer(this::definePlaceholderBean)
+				.run((context) -> assertThat(context.getBean(PlaceholderBean.class).fruit).isEqualTo("${fruit:apple}"));
 	}
 
 	@Test
-	void propertyPlaceholders() {
-		this.context.register(PropertyPlaceholderAutoConfiguration.class, PlaceholderConfig.class);
-		TestPropertyValues.of("foo:two").applyTo(this.context);
-		this.context.refresh();
-		assertThat(this.context.getBean(PlaceholderConfig.class).getFoo()).isEqualTo("two");
+	void whenTheAutoConfigurationIsUsedThenBeanDefinitionPlaceholdersAreResolved() {
+		this.contextRunner.withPropertyValues("fruit:banana").withInitializer(this::definePlaceholderBean)
+				.withConfiguration(AutoConfigurations.of(PropertyPlaceholderAutoConfiguration.class))
+				.run((context) -> assertThat(context.getBean(PlaceholderBean.class).fruit).isEqualTo("banana"));
 	}
 
 	@Test
-	void propertyPlaceholdersOverride() {
-		this.context.register(PropertyPlaceholderAutoConfiguration.class, PlaceholderConfig.class,
-				PlaceholdersOverride.class);
-		TestPropertyValues.of("foo:two").applyTo(this.context);
-		this.context.refresh();
-		assertThat(this.context.getBean(PlaceholderConfig.class).getFoo()).isEqualTo("spam");
+	void whenTheAutoConfigurationIsNotUsedThenValuePlaceholdersAreResolved() {
+		this.contextRunner.withPropertyValues("fruit:banana").withUserConfiguration(PlaceholderConfig.class)
+				.run((context) -> assertThat(context.getBean(PlaceholderConfig.class).fruit).isEqualTo("banana"));
+	}
+
+	@Test
+	void whenTheAutoConfigurationIsUsedThenValuePlaceholdersAreResolved() {
+		this.contextRunner.withPropertyValues("fruit:banana")
+				.withConfiguration(AutoConfigurations.of(PropertyPlaceholderAutoConfiguration.class))
+				.withUserConfiguration(PlaceholderConfig.class)
+				.run((context) -> assertThat(context.getBean(PlaceholderConfig.class).fruit).isEqualTo("banana"));
+	}
+
+	@Test
+	void whenThereIsAUserDefinedPropertySourcesPlaceholderConfigurerThenItIsUsedForBeanDefinitionPlaceholderResolution() {
+		this.contextRunner.withPropertyValues("fruit:banana").withInitializer(this::definePlaceholderBean)
+				.withConfiguration(AutoConfigurations.of(PropertyPlaceholderAutoConfiguration.class))
+				.withUserConfiguration(PlaceholdersOverride.class)
+				.run((context) -> assertThat(context.getBean(PlaceholderBean.class).fruit).isEqualTo("orange"));
+	}
+
+	@Test
+	void whenThereIsAUserDefinedPropertySourcesPlaceholderConfigurerThenItIsUsedForValuePlaceholderResolution() {
+		this.contextRunner.withPropertyValues("fruit:banana")
+				.withConfiguration(AutoConfigurations.of(PropertyPlaceholderAutoConfiguration.class))
+				.withUserConfiguration(PlaceholderConfig.class, PlaceholdersOverride.class)
+				.run((context) -> assertThat(context.getBean(PlaceholderConfig.class).fruit).isEqualTo("orange"));
+	}
+
+	private void definePlaceholderBean(ConfigurableApplicationContext context) {
+		((BeanDefinitionRegistry) context.getBeanFactory()).registerBeanDefinition("placeholderBean",
+				BeanDefinitionBuilder.genericBeanDefinition(PlaceholderBean.class)
+						.addConstructorArgValue("${fruit:apple}").getBeanDefinition());
 	}
 
 	@Configuration(proxyBeanMethods = false)
 	static class PlaceholderConfig {
 
-		@Value("${foo:bar}")
-		private String foo;
+		@Value("${fruit:apple}")
+		private String fruit;
 
-		String getFoo() {
-			return this.foo;
+	}
+
+	static class PlaceholderBean {
+
+		private final String fruit;
+
+		PlaceholderBean(String fruit) {
+			this.fruit = fruit;
 		}
 
 	}
@@ -80,7 +114,8 @@ class PropertyPlaceholderAutoConfigurationTests {
 		@Bean
 		static PropertySourcesPlaceholderConfigurer morePlaceholders() {
 			PropertySourcesPlaceholderConfigurer configurer = new PropertySourcesPlaceholderConfigurer();
-			configurer.setProperties(StringUtils.splitArrayElementsIntoProperties(new String[] { "foo=spam" }, "="));
+			configurer
+					.setProperties(StringUtils.splitArrayElementsIntoProperties(new String[] { "fruit=orange" }, "="));
 			configurer.setLocalOverride(true);
 			configurer.setOrder(0);
 			return configurer;