title: @TestPropertySource doesn't work for JUnit test with AnnotationConfigContextLoader in Spring 1.2.6
body: <p>It doesn't seem that anything I do in Spring 4.1.17 with Spring Boot 1.2.6.RELEASE works at all.  I just want to access the application properties and override them with test if necessary (without using the hack to inject a PropertySource manually)</p>
  
  <p>this doesn't work..</p>
  
  <pre><code>@TestPropertySource(properties = {"elastic.index=test_index"})
  </code></pre>
  
  <p>nor does this..</p>
  
  <pre><code>@TestPropertySource(locations = "/classpath:document.properties")
  </code></pre>
  
  <p>nor this..</p>
  
  <pre><code>@PropertySource("classpath:/document.properties")
  </code></pre>
  
  <p>full test case..</p>
  
  <pre><code>@RunWith(SpringJUnit4ClassRunner.class)
  @ContextConfiguration(loader = AnnotationConfigContextLoader.class)
  @TestPropertySource(properties = {"elastic.index=test_index"})
  public class PropertyTests {
      @Value("${elastic.index}")
      String index;
  
      @Configuration
      @TestPropertySource(properties = {"elastic.index=test_index"})
      static class ContextConfiguration {
      }
  
      @Test
      public void wtf() {
          assertEquals("test_index", index);
      }
  }
  </code></pre>
  
  <p>resulting in </p>
  
  <pre><code>org.junit.ComparisonFailure: 
  Expected :test_index
  Actual   :${elastic.index}
  </code></pre>
  
  <p>It seems there is a lot of conflicting information between 3.x and 4.x and I can't find anything that will work for sure.  </p>
  
  <p>Any insight would be gratefully appreciated.  Cheers!</p>