Issue 21377. Specify that navigation regions are sorted and implement it.

pkg/analysis_server/test/analysis/notification_navigation_test.dart

 // Copyright (c) 2014, 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 test.analysis.notification.navigation;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
@@ skipping 105 matching lines @@
 
   /**
    * Validates that there is no a region for [search] string.
    */
   void assertNoRegionString(String search) {
     int offset = findOffset(search);
     int length = search.length;
     findRegion(offset, length, false);
   }
 
+  void assertRegionsSorted() {
+    int lastEnd = -1;
+    for (NavigationRegion region in regions) {
+      int offset = region.offset;
+      if (offset < lastEnd) {
+        fail('$lastEnd was expected to be > $offset in\n' + regions.join('\n'));
+      }
+      lastEnd = offset + region.length;
+    }
+  }
+
   /**
    * Finds the navigation region with the given [offset] and [length].
    * If [length] is `-1`, then it is ignored.
    *
    * If [exists] is `true`, then fails if such region does not exist.
    * Otherwise remembers this it into [testRegion].
    * Also fills [testTargets] with its targets.
    *
    * If [exists] is `false`, then fails if such region exists.
    */
@@ skipping 13 matching lines @@
     }
     if (exists == true) {
       fail(
           'Expected to find (offset=$offset; length=$length) in\n'
               '${regions.join('\n')}');
     }
   }
 
   Future prepareNavigation() {
     addAnalysisSubscription(AnalysisService.NAVIGATION, testFile);
-    return waitForTasksFinished();
+    return waitForTasksFinished().then((_) {
+      assertRegionsSorted();
+    });
   }
 
   void processNotification(Notification notification) {
     if (notification.event == ANALYSIS_NAVIGATION) {
       var params = new AnalysisNavigationParams.fromNotification(notification);
       if (params.file == testFile) {
         regions = params.regions;
       }
     }
   }
@@ skipping 106 matching lines @@
     addTestFile('''
 main() {
   print(vvv);
 }
 ''');
     return prepareNavigation().then((_) {
       assertNoRegionString('vvv');
     });
   }
 
+  test_identifier_whenStrayImportDirective() {
+    addTestFile('''
+main() {
+  int aaa = 42;
+  print(aaa);
+}
+import 'dart:math';
+''');
+    return prepareNavigation().then((_) {
+      assertHasRegionTarget('aaa);', 'aaa = 42');
+    });
+  }
+
   test_instanceCreation_implicit() {
     addTestFile('''
 class A {
 }
 main() {
   new A();
 }
 ''');
     return prepareNavigation().then((_) {
       findRegion(findOffset('new A'), 'new A'.length, true);
       assertHasTarget('A {');
     });
   }
 
   test_instanceCreation_named() {
     addTestFile('''
 class A {
   A.named() {}
 }
 main() {
   new A.named();
 }
 ''');
     return prepareNavigation().then((_) {
       {
-        findRegion(findOffset('new '), 'new '.length, true);
+        findRegion(findOffset('new '), 'new'.length, true);
         assertHasTarget('named() {}');
       }
       {
         findRegion(findOffset('A.named();'), 'A'.length, true);
         assertHasTarget('A {');
       }
       {
         findRegion(findOffset('.named();'), '.named'.length, true);
         assertHasTarget('named() {}');
       }
     });
   }
 
   test_instanceCreation_unnamed() {
     addTestFile('''
 class A {
   A() {}
 }
 main() {
   new A();
 }
 ''');
     return prepareNavigation().then((_) {
       {
-        findRegion(findOffset('new '), 'new '.length, true);
+        findRegion(findOffset('new '), 'new'.length, true);
         assertHasTarget('A() {}', 0);
       }
       {
         findRegion(findOffset('A();'), 'A'.length, true);
         assertHasTarget('A {');
       }
     });
   }
 
   test_operator_arithmetic() {
@@ skipping 164 matching lines @@
   test_type_void() {
     addTestFile('''
 void main() {
 }
 ''');
     return prepareNavigation().then((_) {
       assertNoRegionAt('void');
     });
   }
 }