Fix analysis server 'analysis.getHover' when there is no hover information.

pkg/analysis_server/test/analysis_hover_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.hover;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/computer/computer_hover.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_testing/reflective_tests.dart';
 import 'package:unittest/unittest.dart';
 
 import 'analysis_abstract.dart';
 
 
 main() {
   group('notification.hover', () {
     runReflectiveTests(AnalysisHoverTest);
   });
 }
 
 
 @ReflectiveTestCase()
 class AnalysisHoverTest extends AbstractAnalysisTest {
-  List<Hover> hovers;
-  Hover hover;
-
-  Future prepareHover(String search, then()) {
+  Future<Hover> prepareHover(String search) {
     int offset = findOffset(search);
-    return prepareHoverAt(offset, then);
+    return prepareHoverAt(offset);
   }
 
-  Future prepareHoverAt(int offset, then()) {
+  Future<Hover> prepareHoverAt(int offset) {
     return waitForTasksFinished().then((_) {
       Request request = new Request('0', ANALYSIS_GET_HOVER);
       request.setParameter(FILE, testFile);
       request.setParameter(OFFSET, offset);
       Response response = handleSuccessfulRequest(request);
       List<Map<String, Object>> hoverJsons = response.getResult(HOVERS);
-      hovers = hoverJsons.map((json) {
+      List<Hover> hovers = hoverJsons.map((json) {
         return new Hover.fromJson(json);
       }).toList();
-      hover = hovers.isNotEmpty ? hovers.first : null;
-      then();
+      return hovers.isNotEmpty ? hovers.first : null;
     });
   }
 
   @override
   void setUp() {
     super.setUp();
     createProject();
   }
 
   test_dartDoc_clunky() {
     addTestFile('''
 library my.library;
 /**
  * doc aaa
  * doc bbb
  */
 main() {
 }
 ''');
-    return prepareHover('main() {', () {
+    return prepareHover('main() {').then((Hover hover) {
       expect(hover.dartDoc, '''doc aaa\ndoc bbb''');
     });
   }
 
   test_dartDoc_elegant() {
     addTestFile('''
 library my.library;
 /// doc aaa
 /// doc bbb
 main() {
 }
 ''');
-    return prepareHover('main() {', () {
+    return prepareHover('main() {').then((Hover hover) {
       expect(hover.dartDoc, '''doc aaa\ndoc bbb''');
     });
   }
 
   test_expression_function() {
     addTestFile('''
 library my.library;
 /// doc aaa
 /// doc bbb
 List<String> fff(int a, String b) {
 }
 ''');
-    return prepareHover('fff(int a', () {
+    return prepareHover('fff(int a').then((Hover hover) {
       // element
       expect(hover.containingLibraryName, 'my.library');
       expect(hover.containingLibraryPath, testFile);
       expect(hover.dartDoc, '''doc aaa\ndoc bbb''');
       expect(hover.elementDescription, 'fff(int a, String b) → List<String>');
       expect(hover.elementKind, 'function');
       // types
       expect(hover.staticType, '(int, String) → List<String>');
       expect(hover.propagatedType, isNull);
       // no parameter
       expect(hover.parameter, isNull);
     });
   }
 
   test_expression_literal_noElement() {
     addTestFile('''
 main() {
   foo(123);
 }
 foo(Object myParameter) {}
 ''');
-    return prepareHover('123', () {
+    return prepareHover('123').then((Hover hover) {
       // literal, no Element
       expect(hover.elementDescription, isNull);
       expect(hover.elementKind, isNull);
       // types
       expect(hover.staticType, 'int');
       expect(hover.propagatedType, isNull);
       // parameter
       expect(hover.parameter, 'Object myParameter');
     });
   }
 
   test_expression_method() {
     addTestFile('''
 library my.library;
 class A {
   /// doc aaa
   /// doc bbb
   List<String> mmm(int a, String b) {
   }
 }
 ''');
-    return prepareHover('mmm(int a', () {
+    return prepareHover('mmm(int a').then((Hover hover) {
       // element
       expect(hover.containingLibraryName, 'my.library');
       expect(hover.containingLibraryPath, testFile);
       expect(hover.dartDoc, '''doc aaa\ndoc bbb''');
       expect(hover.elementDescription, 'A.mmm(int a, String b) → List<String>');
       expect(hover.elementKind, 'method');
       // types
       expect(hover.staticType, '(int, String) → List<String>');
       expect(hover.propagatedType, isNull);
       // no parameter
       expect(hover.parameter, isNull);
     });
   }
 
   test_expression_method_nvocation() {
     addTestFile('''
 library my.library;
 class A {
   List<String> mmm(int a, String b) {
   }
 }
 main(A a) {
   a.mmm(42, 'foo');
 }
 ''');
-    return prepareHover('mm(42, ', () {
+    return prepareHover('mm(42, ').then((Hover hover) {
       // range
       expect(hover.offset, findOffset('mmm(42, '));
       expect(hover.length, 'mmm'.length);
       // element
       expect(hover.containingLibraryName, 'my.library');
       expect(hover.containingLibraryPath, testFile);
       expect(hover.elementDescription, 'A.mmm(int a, String b) → List<String>');
       expect(hover.elementKind, 'method');
       // types
       expect(hover.staticType, isNull);
       expect(hover.propagatedType, isNull);
       // no parameter
       expect(hover.parameter, isNull);
     });
   }
 
   test_expression_syntheticGetter() {
     addTestFile('''
 library my.library;
 class A {
   /// doc aaa
   /// doc bbb
   String fff;
 }
 main(A a) {
   print(a.fff);
 }
 ''');
-    return prepareHover('fff);', () {
+    return prepareHover('fff);').then((Hover hover) {
       // element
       expect(hover.containingLibraryName, 'my.library');
       expect(hover.containingLibraryPath, testFile);
       expect(hover.dartDoc, '''doc aaa\ndoc bbb''');
       expect(hover.elementDescription, 'String fff');
       expect(hover.elementKind, 'field');
       // types
       expect(hover.staticType, 'String');
       expect(hover.propagatedType, isNull);
     });
   }
 
   test_expression_variable_hasPropagatedType() {
     addTestFile('''
 library my.library;
 main() {
   var vvv = 123;
   print(vvv);
 }
 ''');
-    return prepareHover('vvv);', () {
+    return prepareHover('vvv);').then((Hover hover) {
       // element
       expect(hover.containingLibraryName, 'my.library');
       expect(hover.containingLibraryPath, testFile);
       expect(hover.dartDoc, isNull);
       expect(hover.elementDescription, 'dynamic vvv');
       expect(hover.elementKind, 'local variable');
       // types
       expect(hover.staticType, 'dynamic');
       expect(hover.propagatedType, 'int');
     });
   }
+
+  test_noHoverInfo() {
+    addTestFile('''
+library my.library;
+main() {
+  // nothing
 }
+''');
+    return prepareHover('nothing').then((Hover hover) {
+      expect(hover, isNull);
+    });
+  }
+}