Improve tests for PropertySourcesPlaceholderConfigurer

spring-context/src/test/java/org/springframework/context/annotation/configuration/ConfigurationClassWithPlaceholderConfigurerBeanTests.java

 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -16,7 +16,6 @@
 
 package org.springframework.context.annotation.configuration;
 
-import org.junit.Ignore;
 import org.junit.Test;
 
 import org.springframework.beans.factory.annotation.Value;
@@ -31,28 +30,37 @@ import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.*;
 
 /**
- * A configuration class that registers a placeholder configurer @Bean method
- * cannot also have @Value fields.  Logically, the config class must be instantiated
- * in order to invoke the placeholder configurer bean method, and it is a
- * chicken-and-egg problem to process the @Value field.
+ * A configuration class that registers a non-static placeholder configurer {@code @Bean}
+ * method cannot also have {@code @Value} fields. Logically, the config class must be
+ * instantiated in order to invoke the placeholder configurer bean method, and it is a
+ * chicken-and-egg problem to process the {@code @Value} field.
  *
- * Therefore, placeholder configurers should be put in separate configuration classes
- * as has been done in the test below. Simply said, placeholder configurer @Bean methods
- * and @Value fields in the same configuration class are mutually exclusive.
+ * <p>Therefore, placeholder configurer bean methods should either be {@code static} or
+ * put in separate configuration classes as has been done in the tests below. Simply said,
+ * placeholder configurer {@code @Bean} methods and {@code @Value} fields in the same
+ * configuration class are mutually exclusive unless the placeholder configurer
+ * {@code @Bean} method is {@code static}.
  *
  * @author Chris Beams
  * @author Juergen Hoeller
+ * @author Sam Brannen
  */
 public class ConfigurationClassWithPlaceholderConfigurerBeanTests {
 
 	/**
-	 * Intentionally ignored test proving that a property placeholder bean
-	 * cannot be declared in the same configuration class that has a @Value
-	 * field in need of placeholder replacement. It's an obvious chicken-and-egg issue.
-	 * The solution is to do as {@link #valueFieldsAreProcessedWhenPlaceholderConfigurerIsSegregated()}
+	 * Test which proves that a non-static property placeholder bean cannot be declared
+	 * in the same configuration class that has a {@code @Value} field in need of
+	 * placeholder replacement. It's an obvious chicken-and-egg issue.
+	 *
+	 * <p>One solution is to do as {@link #valueFieldsAreProcessedWhenPlaceholderConfigurerIsSegregated()}
 	 * does and segregate the two bean definitions across configuration classes.
+	 *
+	 * <p>Another solution is to simply make the {@code @Bean} method for the property
+	 * placeholder {@code static} as in
+	 * {@link #valueFieldsAreProcessedWhenStaticPlaceholderConfigurerIsIntegrated()}.
 	 */
-	@Ignore @Test
+	@Test
+	@SuppressWarnings("resource")
 	public void valueFieldsAreNotProcessedWhenPlaceholderConfigurerIsIntegrated() {
 		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
 		ctx.register(ConfigWithValueFieldAndPlaceholderConfigurer.class);
@@ -61,10 +69,25 @@ public class ConfigurationClassWithPlaceholderConfigurerBeanTests {
 		System.clearProperty("test.name");
 
 		TestBean testBean = ctx.getBean(TestBean.class);
+		// Proof that the @Value field did not get set:
 		assertThat(testBean.getName(), nullValue());
 	}
 
 	@Test
+	@SuppressWarnings("resource")
+	public void valueFieldsAreProcessedWhenStaticPlaceholderConfigurerIsIntegrated() {
+		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
+		ctx.register(ConfigWithValueFieldAndStaticPlaceholderConfigurer.class);
+		System.setProperty("test.name", "foo");
+		ctx.refresh();
+		System.clearProperty("test.name");
+
+		TestBean testBean = ctx.getBean(TestBean.class);
+		assertThat(testBean.getName(), equalTo("foo"));
+	}
+
+	@Test
+	@SuppressWarnings("resource")
 	public void valueFieldsAreProcessedWhenPlaceholderConfigurerIsSegregated() {
 		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
 		ctx.register(ConfigWithValueField.class);
@@ -78,7 +101,8 @@ public class ConfigurationClassWithPlaceholderConfigurerBeanTests {
 	}
 
 	@Test
-	public void valueFieldsResolveToPlaceholderSpecifiedDefaultValue() {
+	@SuppressWarnings("resource")
+	public void valueFieldsResolveToPlaceholderSpecifiedDefaultValuesWithPlaceholderConfigurer() {
 		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
 		ctx.register(ConfigWithValueField.class);
 		ctx.register(ConfigWithPlaceholderConfigurer.class);
@@ -88,6 +112,18 @@ public class ConfigurationClassWithPlaceholderConfigurerBeanTests {
 		assertThat(testBean.getName(), equalTo("bar"));
 	}
 
+	@Test
+	@SuppressWarnings("resource")
+	public void valueFieldsResolveToPlaceholderSpecifiedDefaultValuesWithoutPlaceholderConfigurer() {
+		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
+		ctx.register(ConfigWithValueField.class);
+		// ctx.register(ConfigWithPlaceholderConfigurer.class);
+		ctx.refresh();
+
+		TestBean testBean = ctx.getBean(TestBean.class);
+		assertThat(testBean.getName(), equalTo("bar"));
+	}
+
 
 	@Configuration
 	static class ConfigWithValueField {
@@ -129,4 +165,21 @@ public class ConfigurationClassWithPlaceholderConfigurerBeanTests {
 		}
 	}
 
+	@Configuration
+	static class ConfigWithValueFieldAndStaticPlaceholderConfigurer {
+
+		@Value("${test.name}")
+		private String name;
+
+		@Bean
+		public ITestBean testBean() {
+			return new TestBean(this.name);
+		}
+
+		@Bean
+		public static PropertySourcesPlaceholderConfigurer ppc() {
+			return new PropertySourcesPlaceholderConfigurer();
+		}
+	}
+
 }