Test dependency tracking of unused imports/exports.

pkg/analyzer/test/src/summary/summary_test.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.test.src.summary.summary_test;
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
@@ skipping 540 matching lines @@
    */
   void checkUnresolvedTypeRef(
       UnlinkedTypeRef typeRef, String expectedPrefix, String expectedName) {
     // When serializing from the element model, unresolved type refs lose their
     // name.
     checkTypeRef(typeRef, null, null, checkAstDerivedData ? expectedName : null,
         expectedPrefix: expectedPrefix,
         expectedKind: PrelinkedReferenceKind.unresolved);
   }
 
+  fail_dependencies_export_to_export_unused() {
+    // TODO(paulberry): fix this test.
+    addNamedSource('/a.dart', 'export "b.dart";');
+    addNamedSource('/b.dart', '');
+    serializeLibraryText('export "a.dart";');
+    // The main test library depends on b.dart, even though it doesn't
+    // re-export any names defined in b.dart, because a change to b.dart might
+    // cause it to start exporting a name that the main test library *does*
+    // use.
+    checkHasDependency(absUri('/b.dart'), 'b.dart');
+  }
+
+  fail_dependencies_export_unused() {
+    // TODO(paulberry): fix this test.
+    addNamedSource('/a.dart', '');
+    serializeLibraryText('export "a.dart";');
+    // The main test library depends on a.dart, even though it doesn't
+    // re-export any names defined in a.dart, because a change to a.dart might
+    // cause it to start exporting a name that the main test library *will*
+    // re-export.
+    checkHasDependency(absUri('/a.dart'), 'a.dart');
+  }
+
   fail_enum_value_documented() {
     // TODO(paulberry): currently broken because of dartbug.com/25385
     String text = '''
 enum E {
   /**
    * Docs
    */
   v
 }''';
     UnlinkedEnumValue value = serializeEnumText(text).values[0];
@@ skipping 951 matching lines @@
     addNamedSource('/a.dart', 'library a; export "b.dart"; class A {}');
     addNamedSource('/b.dart', 'library b; export "c.dart";');
     addNamedSource('/c.dart', 'library c;');
     serializeLibraryText('import "a.dart"; A a;');
     checkHasDependency(absUri('/a.dart'), 'a.dart');
     // The main test library depends on c.dart, because names defined in
     // c.dart are exported by b.dart and then re-exported by a.dart.
     checkHasDependency(absUri('/c.dart'), 'c.dart');
   }
 
+  test_dependencies_import_to_export_unused() {
+    addNamedSource('/a.dart', 'export "b.dart";');
+    addNamedSource('/b.dart', '');
+    serializeLibraryText('import "a.dart";', allowErrors: true);
+    // The main test library depends on b.dart, even though it doesn't use any
+    // names defined in b.dart, because a change to b.dart might cause it to
+    // start exporting a name that the main test library *does* use.
+    checkHasDependency(absUri('/b.dart'), 'b.dart');
+  }
+
   test_dependencies_import_transitive_closure() {
     addNamedSource(
         '/a.dart', 'library a; import "b.dart"; class A extends B {}');
     addNamedSource('/b.dart', 'library b; class B {}');
     serializeLibraryText('import "a.dart"; A a;');
     checkHasDependency(absUri('/a.dart'), 'a.dart');
     // The main test library doesn't depend on b.dart, because no change to
     // b.dart can possibly affect the serialized element model for it.
     checkLacksDependency(absUri('/b.dart'), 'b.dart');
   }
 
+  test_dependencies_import_unused() {
+    addNamedSource('/a.dart', '');
+    serializeLibraryText('import "a.dart";', allowErrors: true);
+    // The main test library depends on a.dart, even though it doesn't use any
+    // names defined in a.dart, because a change to a.dart might cause it to
+    // start exporting a name that the main test library *does* use.
+    checkHasDependency(absUri('/a.dart'), 'a.dart');
+  }
+
   test_dependencies_parts() {
     addNamedSource(
         '/a.dart', 'library a; part "b.dart"; part "c.dart"; class A {}');
     addNamedSource('/b.dart', 'part of a;');
     addNamedSource('/c.dart', 'part of a;');
     serializeLibraryText('import "a.dart"; A a;');
     PrelinkedDependency dep = checkHasDependency(absUri('/a.dart'), 'a.dart');
     checkDependencyParts(
         dep, [absUri('/b.dart'), absUri('/c.dart')], ['b.dart', 'c.dart']);
   }
@@ skipping 1404 matching lines @@
     UnlinkedVariable variable =
         serializeVariableText('int i;', variableName: 'i');
     checkTypeRef(variable.type, 'dart:core', 'dart:core', 'int');
   }
 
   test_varible_private() {
     serializeVariableText('int _i;', variableName: '_i');
     expect(unlinkedUnits[0].publicNamespace.names, isEmpty);
   }
 }