Add and use AnalysisCache.sources getter.

pkg/analyzer/test/src/context/cache_test.dart

Index: pkg/analyzer/test/src/context/cache_test.dart
diff --git a/pkg/analyzer/test/src/context/cache_test.dart b/pkg/analyzer/test/src/context/cache_test.dart
index f093931059f89867317e21c65fa702964fde4f8b..94ae434c211328a01ce3da9489f6ca994692cbba 100644
--- a/pkg/analyzer/test/src/context/cache_test.dart
+++ b/pkg/analyzer/test/src/context/cache_test.dart
@@ -183,6 +183,29 @@ class AnalysisCacheTest extends AbstractCacheTest {
     }
     expect(cache.size(), size);
   }
+
+  void test_sources() {
+    AnalysisTarget source1 = new TestSource('1.dart');
+    AnalysisTarget source2 = new TestSource('2.dart');
+    AnalysisTarget target1 = new _TestAnalysisTarget();
+    // no entries
+    expect(cache.sources, isEmpty);
+    // add source1
+    cache.put(new CacheEntry(source1));
+    expect(cache.sources, unorderedEquals([source1]));
+    // add target1
+    cache.put(new CacheEntry(target1));
+    expect(cache.sources, unorderedEquals([source1]));
+    // add source2
+    cache.put(new CacheEntry(source2));
+    expect(cache.sources, unorderedEquals([source1, source2]));
+    // remove source1
+    cache.remove(source1);
+    expect(cache.sources, unorderedEquals([source2]));
+    // remove source2
+    cache.remove(source2);
+    expect(cache.sources, isEmpty);
+  }
 }
 
 @reflectiveTest
@@ -842,3 +865,8 @@ class _InternalAnalysisContextMock extends TypedMock
     implements InternalAnalysisContext {
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }
+
+class _TestAnalysisTarget implements AnalysisTarget {

[Brian Wilkerson, 2015/05/21 13:52:31]

Don't we already have this class somewhere?

+  @override
+  Source get source => null;
+}