Suggest constructors for implicit creation in previewDart2.

R=brianwilkerson@google.com

Bug: https://github.com/flutter/flutter-intellij/issues/998
Change-Id: I43270f47fb43402d1a9e0f7d9814494ffd83bb5e
Reviewed-on: https://dart-review.googlesource.com/43080
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analysis_server/lib/src/services/completion/dart/static_member_contributor.dart

@@ -67,6 +67,13 @@ class _SuggestionBuilder extends GeneralizingElementVisitor {
     // ignored
   }
 
+  @override
+  visitConstructorElement(ConstructorElement element) {
+    if (element.context.analysisOptions.previewDart2) {
+      _addSuggestion(element);
+    }
+  }
+
   @override
   visitFieldElement(FieldElement element) {
     if (element.isStatic) {

pkg/analysis_server/test/abstract_context.dart

@@ -89,6 +89,12 @@ class Required {
     return source;
   }
 
+  void configurePreviewDart2() {
+    driver.configure(
+        analysisOptions: new AnalysisOptionsImpl.from(driver.analysisOptions)
+          ..previewDart2 = true);
+  }
+
   void processRequiredPlugins() {
     AnalysisEngine.instance.processRequiredPlugins();
   }

pkg/analysis_server/test/completion_test.dart

@@ -781,21 +781,17 @@ main() {
         <String>["1+fooConst", "1-fooNotConst", "1-bar"],
         failingTests: '1');
 
-    buildTests(
-        'testCompletion_annotation_type',
-        '''
+    buildTests('testCompletion_annotation_type', '''
 class AAA {
   const AAA({int a, int b});
   const AAA.nnn(int c, int d);
 }
 @AAA!1
 main() {
-}''',
-        <String>[
-          "1+AAA" /*":" + ProposalKind.CONSTRUCTOR*/,
-          "1+AAA.nnn" /*":" + ProposalKind.CONSTRUCTOR*/
-        ],
-        failingTests: '1');
+}''', <String>[
+      "1+AAA" /*":" + ProposalKind.CONSTRUCTOR*/,
+      "1+AAA.nnn" /*":" + ProposalKind.CONSTRUCTOR*/
+    ]);
 
     buildTests('testCompletion_annotation_type_inClass_withoutMember', '''
 class AAA {

pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart

@@ -198,6 +198,7 @@ abstract class DartCompletionContributorTest extends AbstractContextTest {
   CompletionSuggestion assertSuggestConstructor(String name,
       {int relevance: DART_RELEVANCE_DEFAULT,
       String importUri,
+      String elementName,
       int elemOffset,
       String defaultArgListString: _UNCHECKED,
       List<int> defaultArgumentListTextRanges}) {
@@ -211,7 +212,8 @@ abstract class DartCompletionContributorTest extends AbstractContextTest {
     expect(element, isNotNull);
     expect(element.kind, equals(ElementKind.CONSTRUCTOR));
     int index = name.indexOf('.');
-    expect(element.name, index >= 0 ? name.substring(index + 1) : '');
+    elementName ??= index >= 0 ? name.substring(index + 1) : '';
+    expect(element.name, elementName);
     return cs;
   }
 

pkg/analysis_server/test/services/completion/dart/imported_reference_contributor_test.dart

@@ -2381,6 +2381,36 @@ class B extends A {
     assertNotSuggested('int');
   }
 
+  test_implicitCreation() async {
+    configurePreviewDart2();
+    addSource('/a.dart', '''
+class A {
+  A.a1();
+  A.a2();
+}
+class B {
+  B.b1();
+  B.b2();
+}
+''');
+    addTestSource('''
+import 'a.dart';
+
+main() {
+  ^;
+}
+''');
+    await computeSuggestions();
+
+    assertSuggestClass('A');
+    assertSuggestConstructor('A.a1');
+    assertSuggestConstructor('A.a2');
+
+    assertSuggestClass('B');
+    assertSuggestConstructor('B.b1');
+    assertSuggestConstructor('B.b2');
+  }
+
   test_ImportDirective_dart() async {
     // SimpleStringLiteral  ImportDirective
     addTestSource('''

pkg/analysis_server/test/services/completion/dart/static_member_contributor_test.dart

@@ -97,6 +97,27 @@ class StaticMemberContributorTest extends DartCompletionContributorTest {
     assertSuggestField('values', 'List<E>', isDeprecated: true);
   }
 
+  test_implicitCreation() async {
+    configurePreviewDart2();
+    addSource('/a.dart', '''
+class A {
+  A.foo();
+  A.bar();
+}
+''');
+    addTestSource('''
+import 'a.dart';
+
+main() {
+  A.^;
+}
+''');
+    await computeSuggestions();
+
+    assertSuggestConstructor('foo', elementName: 'foo');
+    assertSuggestConstructor('bar', elementName: 'bar');
+  }
+
   test_keyword() async {
     addTestSource('class C { static C get instance => null; } main() {C.in^}');
     await computeSuggestions();

pkg/analysis_server/test/services/correction/assist_test.dart

@@ -3258,7 +3258,7 @@ class FakeFlutter {
   }
 
   test_flutterWrapCenter_OK_implicitNew() async {
-    _configurePreviewDart2();
+    configurePreviewDart2();
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -3352,7 +3352,7 @@ class FakeFlutter {
   }
 
   test_flutterWrapColumn_OK_implicitNew() async {
-    _configurePreviewDart2();
+    configurePreviewDart2();
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -5330,12 +5330,6 @@ main() {
     return await processor.compute();
   }
 
-  void _configurePreviewDart2() {
-    driver.configure(
-        analysisOptions: new AnalysisOptionsImpl.from(driver.analysisOptions)
-          ..previewDart2 = true);
-  }
-
   List<Position> _findResultPositions(List<String> searchStrings) {
     List<Position> positions = <Position>[];
     for (String search in searchStrings) {

pkg/analyzer_plugin/lib/src/utilities/completion/optype.dart

@@ -125,6 +125,16 @@ class OpType {
         target.containingNode.getAncestor((p) => p is MethodDeclaration);
     optype.inStaticMethodBody =
         mthDecl is MethodDeclaration && mthDecl.isStatic;
+
+    // If a value should be suggested, suggest also constructors.
+    if (optype.includeReturnValueSuggestions) {
+      CompilationUnitElement unitElement = target.unit.element;
+      if (unitElement != null &&
+          unitElement.context.analysisOptions.previewDart2) {
+        optype.includeConstructorSuggestions = true;
+      }
+    }
+
     return optype;
   }