Share LibrarySpecificUnits when possible

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

Index: pkg/analyzer/test/src/context/context_test.dart
diff --git a/pkg/analyzer/test/src/context/context_test.dart b/pkg/analyzer/test/src/context/context_test.dart
index a851f55013cb35dd0e1293a146ce75ee23a92449..042ce4e228c41dace5d908687ef81fc52ac3d11a 100644
--- a/pkg/analyzer/test/src/context/context_test.dart
+++ b/pkg/analyzer/test/src/context/context_test.dart
@@ -1422,6 +1422,104 @@ Stream S = null;
     }
   }
 
+  void test_getLibrarySpecificUnit_definingCU_different() {
+    Source source1 = newSource('/lib1.dart');
+    Source source2 = newSource('/lib2.dart');
+    context.applyChanges(
+        new ChangeSet()..addedSource(source1)..addedSource(source2));
+    LibrarySpecificUnit lsu1 = context.getLibrarySpecificUnit(source1, source1);
+    expect(lsu1, isNotNull);
+    expect(lsu1.library, same(source1));
+    expect(lsu1.unit, same(source1));
+    LibrarySpecificUnit lsu2 = context.getLibrarySpecificUnit(source2, source2);
+    expect(lsu2, isNotNull);
+    expect(lsu2.library, same(source2));
+    expect(lsu2.unit, same(source2));
+  }
+
+  void test_getLibrarySpecificUnit_definingCU_explicit() {
+    Source source = newSource('/test.dart');
+    context.applyChanges(new ChangeSet()..addedSource(source));
+    LibrarySpecificUnit lsu1 = context.getLibrarySpecificUnit(source, source);
+    expect(lsu1, isNotNull);
+    expect(lsu1.library, same(source));
+    expect(lsu1.unit, same(source));
+    LibrarySpecificUnit lsu2 = context.getLibrarySpecificUnit(source, source);
+    expect(lsu2, same(lsu1));
+  }
+
+  void test_getLibrarySpecificUnit_definingCU_implicit() {
+    Source source = newSource('/test.dart');
+    LibrarySpecificUnit lsu1 = context.getLibrarySpecificUnit(source, source);
+    expect(lsu1, isNotNull);
+    expect(lsu1.library, same(source));
+    expect(lsu1.unit, same(source));
+    LibrarySpecificUnit lsu2 = context.getLibrarySpecificUnit(source, source);
+    expect(lsu2, equals(lsu1));
+  }
+
+  void test_getLibrarySpecificUnit_part_differentLibraries() {
+    Source library1 = newSource('/lib1.dart');
+    Source library2 = newSource('/lib2.dart');
+    Source part = newSource('/part.dart');
+    context.applyChanges(new ChangeSet()
+      ..addedSource(library1)
+      ..addedSource(library2)
+      ..addedSource(part));
+    LibrarySpecificUnit lsu1 = context.getLibrarySpecificUnit(library1, part);
+    expect(lsu1, isNotNull);
+    expect(lsu1.library, same(library1));
+    expect(lsu1.unit, same(part));
+    LibrarySpecificUnit lsu2 = context.getLibrarySpecificUnit(library2, part);
+    expect(lsu2, isNotNull);
+    expect(lsu2.library, same(library2));
+    expect(lsu2.unit, same(part));
+  }
+
+  void test_getLibrarySpecificUnit_part_differentParts() {
+    Source library = newSource('/lib.dart');
+    Source part1 = newSource('/part1.dart');
+    Source part2 = newSource('/part2.dart');
+    context.applyChanges(new ChangeSet()
+      ..addedSource(library)
+      ..addedSource(part1)
+      ..addedSource(part2));
+    LibrarySpecificUnit lsu1 = context.getLibrarySpecificUnit(library, part1);
+    expect(lsu1, isNotNull);
+    expect(lsu1.library, same(library));
+    expect(lsu1.unit, same(part1));
+    LibrarySpecificUnit lsu2 = context.getLibrarySpecificUnit(library, part2);
+    expect(lsu2, isNotNull);
+    expect(lsu2.library, same(library));
+    expect(lsu2.unit, same(part2));
+  }
+
+  void test_getLibrarySpecificUnit_part_explicit() {
+    Source library = newSource('/lib.dart');
+    Source part = newSource('/part.dart');
+    context
+        .applyChanges(new ChangeSet()..addedSource(library)..addedSource(part));
+    LibrarySpecificUnit lsu1 = context.getLibrarySpecificUnit(library, part);
+    expect(lsu1, isNotNull);
+    expect(lsu1.library, same(library));
+    expect(lsu1.unit, same(part));
+    LibrarySpecificUnit lsu2 = context.getLibrarySpecificUnit(library, part);
+    expect(lsu2, same(lsu1));
+  }
+
+  void test_getLibrarySpecificUnit_part_implicit() {
+    Source library = newSource('/lib.dart');
+    Source part = newSource('/part.dart');
+    LibrarySpecificUnit lsu1 = context.getLibrarySpecificUnit(library, part);
+    expect(lsu1, isNotNull);
+    expect(lsu1.library, same(library));
+    expect(lsu1.unit, same(part));
+    LibrarySpecificUnit lsu2 = context.getLibrarySpecificUnit(library, part);
+    expect(lsu2, isNotNull);
+    expect(lsu2.library, same(library));
+    expect(lsu2.unit, same(part));
+  }
+
   void test_getLineInfo() {
     Source source = addSource(
         "/test.dart",