Correctly handle adding imports when pasting into part files

pkg/analysis_server/test/integration/analysis/get_imported_elements_test.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol_generated.dart';
+import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../support/integration_tests.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisGetImportedElementsIntegrationTest);
   });
 }
@@ skipping 12 matching lines @@
   String text;
 
   /**
    * Check that an analysis.getImportedElements request on the region starting
    * with the first character that matches [target] and having the given
    * [length] matches the given list of [expected] imported elements.
    */
   checkElements(String target, List<ImportedElements> expected) async {
     bool equals(
         ImportedElements actualElements, ImportedElements expectedElements) {
-      // We can't test the path because the paths are relative to a generated
-      // temporary directory.
-      if (actualElements.prefix == expectedElements.prefix) {
+      if (actualElements.path.endsWith(expectedElements.path) &&
+          actualElements.prefix == expectedElements.prefix) {
         List<String> actual = actualElements.elements;
         List<String> expected = expectedElements.elements;
         if (actual.length == expected.length) {
           for (int i = 0; i < actual.length; i++) {
             if (!expected.contains(actual[i])) {
               return false;
             }
           }
           return true;
         }
@@ skipping 45 matching lines @@
   }
 
   test_getImportedElements_none() async {
     text = r'''
 main() {}
 ''';
     writeFile(pathname, text);
     standardAnalysisSetup();
     await analysisFinished;
 
-    List<Future> tests = [];
-    tests.add(checkNoElements('main() {}'));
-    return Future.wait(tests);
+    await checkNoElements('main() {}');
   }
 
   test_getImportedElements_some() async {
-    text = r'''
+    String selection = r'''
 main() {
-  String s = '';
+  Random r = new Random();
+  String s = r.nextBool().toString();
   print(s);
 }
 ''';
+    text = '''
+import 'dart:math';
+
+$selection
+''';
     writeFile(pathname, text);
     standardAnalysisSetup();
     await analysisFinished;
 
-    List<Future> tests = [];
-    tests.add(checkElements(text, [
-      new ImportedElements('', '', ['String', 'print'])
-    ]));
-    return Future.wait(tests);
+    await checkElements(selection, [
+      new ImportedElements(
+          path.join('lib', 'core', 'core.dart'), '', ['String', 'print']),
+      new ImportedElements(
+          path.join('lib', 'math', 'math.dart'), '', ['Random'])
+    ]);
   }
 }