Introduce test for PropertySource + ACI in the TCF

This commit introduces an explicit integration test to verify that a
PropertySource can be set via a custom ApplicationContextInitializer in
the Spring TestContext Framework.

Issue: SPR-11666

spring-test/src/test/java/org/springframework/test/context/junit4/aci/annotation/PropertySourcesInitializerTests.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2002-2014 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
+ *
+ * http://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.test.context.junit4.aci.annotation;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
+import org.springframework.core.env.PropertySource;
+import org.springframework.mock.env.MockPropertySource;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import static org.junit.Assert.*;
+
+/**
+ * Integration tests that verify that a {@link PropertySource} can be set via a
+ * custom {@link ApplicationContextInitializer} in the Spring TestContext Framework.
+ *
+ * @author Sam Brannen
+ * @since 4.1
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(initializers = PropertySourcesInitializerTests.PropertySourceInitializer.class)
+public class PropertySourcesInitializerTests {
+
+	@Configuration
+	static class Config {
+
+		@Value("${enigma}")
+		// If the PropertySourcesPlaceholderConfigurer is not configured as a
+		// static @Bean, then the following can be used to directly access the
+		// environment instead of relying on placeholder replacement.
+		// @Value("#{ environment['enigma'] }")
+		private String enigma;
+
+
+		@Bean
+		public String enigma() {
+			return enigma;
+		}
+
+		@Bean
+		public static PropertySourcesPlaceholderConfigurer placeholderConfigurer() {
+			return new PropertySourcesPlaceholderConfigurer();
+		}
+	}
+
+
+	@Autowired
+	private String enigma;
+
+
+	@Test
+	public void customPropertySourceConfiguredViaContextInitializer() {
+		assertEquals("foo", enigma);
+	}
+
+
+	public static class PropertySourceInitializer implements
+			ApplicationContextInitializer<ConfigurableApplicationContext> {
+
+		@Override
+		public void initialize(ConfigurableApplicationContext applicationContext) {
+			applicationContext.getEnvironment().getPropertySources().addFirst(
+				new MockPropertySource().withProperty("enigma", "foo"));
+		}
+	}
+
+}