Use futures uniformly rather than a mix of futures and CPS in tests.

pkg/analysis_server/test/analysis_notification_occurrences_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.domain.analysis.notification.occurrences;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/computer/computer_occurrences.dart';
@@ skipping 64 matching lines @@
         }
       }
     }
     if (exists == true) {
       fail(
           'Expected to find (offset=$offset; length=$length) in\n'
               '${occurrencesList.join('\n')}');
     }
   }
 
-  Future prepareOccurrences(then()) {
+  Future prepareOccurrences() {
     addAnalysisSubscription(AnalysisService.OCCURRENCES, testFile);
-    return waitForTasksFinished().then((_) {
-      then();
-    });
+    return waitForTasksFinished();
   }
 
   void processNotification(Notification notification) {
     if (notification.event == ANALYSIS_OCCURRENCES) {
       String file = notification.getParameter(FILE);
       if (file == testFile) {
         occurrencesList = <Occurrences>[];
         List<Map<String, Object>> jsonList =
             notification.getParameter(OCCURRENCES);
         for (Map<String, Object> json in jsonList) {
@@ skipping 10 matching lines @@
   }
 
   test_afterAnalysis() {
     addTestFile('''
 main() {
   var vvv = 42;
   print(vvv);
 }
 ''');
     return waitForTasksFinished().then((_) {
-      return prepareOccurrences(() {
+      return prepareOccurrences().then((_) {
         assertHasRegion('vvv =');
         expect(testOccurences.element.kind, ElementKind.LOCAL_VARIABLE);
         expect(testOccurences.element.name, 'vvv');
         assertHasOffset('vvv = 42');
         assertHasOffset('vvv);');
       });
     });
   }
 
   test_classType() {
     addTestFile('''
 main() {
   int a = 1;
   int b = 2;
   int c = 3;
 }
 int VVV = 4;
 ''');
-    return prepareOccurrences(() {
+    return prepareOccurrences().then((_) {
       assertHasRegion('int a');
       expect(testOccurences.element.kind, ElementKind.CLASS);
       expect(testOccurences.element.name, 'int');
       assertHasOffset('int a');
       assertHasOffset('int b');
       assertHasOffset('int c');
       assertHasOffset('int VVV');
     });
   }
 
   test_field() {
     addTestFile('''
 class A {
   int fff;
   A(this.fff); // constructor
   main() {
     fff = 42;
     print(fff); // print
   }
 }
 ''');
-    return prepareOccurrences(() {
+    return prepareOccurrences().then((_) {
       assertHasRegion('fff;');
       expect(testOccurences.element.kind, ElementKind.FIELD);
       assertHasOffset('fff); // constructor');
       assertHasOffset('fff = 42;');
       assertHasOffset('fff); // print');
     });
   }
 
   test_localVariable() {
     addTestFile('''
 main() {
   var vvv = 42;
   vvv += 5;
   print(vvv);
 }
 ''');
-    return prepareOccurrences(() {
+    return prepareOccurrences().then((_) {
       assertHasRegion('vvv =');
       expect(testOccurences.element.kind, ElementKind.LOCAL_VARIABLE);
       expect(testOccurences.element.name, 'vvv');
       assertHasOffset('vvv = 42');
       assertHasOffset('vvv += 5');
       assertHasOffset('vvv);');
     });
   }
 
   test_memberField() {
     addTestFile('''
 class A<T> {
   T fff;
 }
 main() {
   var a = new A<int>();
   var b = new A<String>();
   a.fff = 1;
   b.fff = 2;
 }
 ''');
-    return prepareOccurrences(() {
+    return prepareOccurrences().then((_) {
       assertHasRegion('fff;');
       expect(testOccurences.element.kind, ElementKind.FIELD);
       assertHasOffset('fff = 1;');
       assertHasOffset('fff = 2;');
     });
   }
 
   test_memberMethod() {
     addTestFile('''
 class A<T> {
   T mmm() {}
 }
 main() {
   var a = new A<int>();
   var b = new A<String>();
   a.mmm(); // a
   b.mmm(); // b
 }
 ''');
-    return prepareOccurrences(() {
+    return prepareOccurrences().then((_) {
       assertHasRegion('mmm() {}');
       expect(testOccurences.element.kind, ElementKind.METHOD);
       assertHasOffset('mmm(); // a');
       assertHasOffset('mmm(); // b');
     });
   }
 
   test_topLevelVariable() {
     addTestFile('''
 var VVV = 1;
 main() {
   VVV = 2;
   print(VVV);
 }
 ''');
-    return prepareOccurrences(() {
+    return prepareOccurrences().then((_) {
       assertHasRegion('VVV = 1;');
       expect(testOccurences.element.kind, ElementKind.TOP_LEVEL_VARIABLE);
       assertHasOffset('VVV = 2;');
       assertHasOffset('VVV);');
     });
   }
 }