Suggest extension members for an implicit target in extension members

I added one test for this case and several other tests for already
passing cases. I think that some of these cases were failing before the
switch away from using available suggestions for imported libraries and
was originally trying to write a test for a different reported problem,
but the test passed.

Change-Id: I989d8419506c59b883fe5b52168e15fd7d68787c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/201300
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>

Author: bwilkerson

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

@@ -54,6 +54,7 @@ class ExtensionMemberContributor extends DartCompletionContributor {
                       extendedType.element, type.element);
               _addTypeMembers(type, inheritanceDistance);
             }
+            _addExtensionMembers(containingLibrary, extendedType);
           }
         }
       }

pkg/analysis_server/test/src/services/completion/dart/completion_test.dart

@@ -10,6 +10,7 @@ import '../../../../completion_test_support.dart';
 void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConstructorCompletionTest);
+    defineReflectiveTests(ExtensionCompletionTest);
     defineReflectiveTests(PropertyAccessorCompletionTest);
   });
 }
@@ -31,6 +32,142 @@ abstract class C {
   }
 }
 
+@reflectiveTest
+class ExtensionCompletionTest extends CompletionTestCase {
+  Future<void> test_explicitTarget_getter_sameUnit() async {
+    addTestFile('''
+void f(String s) {
+  s.^;
+}
+extension E on String {
+  int get g => length;
+}
+''');
+    await getSuggestions();
+    assertHasCompletion('g');
+  }
+
+  Future<void> test_explicitTarget_method_imported() async {
+    newFile(convertPath('/project/bin/lib.dart'), content: '''
+extension E on String {
+  void m() {}
+}
+''');
+    addTestFile('''
+import 'lib.dart';
+void f(String s) {
+  s.^;
+}
+''');
+    await getSuggestions();
+    assertHasCompletion('m');
+  }
+
+  Future<void> test_explicitTarget_method_inLibrary() async {
+    newFile(convertPath('/project/bin/lib.dart'), content: '''
+part 'test.dart';
+extension E on String {
+  void m() {}
+}
+''');
+    addTestFile('''
+part of 'lib.dart';
+void f(String s) {
+  s.^;
+}
+''');
+    await getSuggestions();
+    assertHasCompletion('m');
+  }
+
+  Future<void> test_explicitTarget_method_inPart() async {
+    newFile(convertPath('/project/bin/part.dart'), content: '''
+extension E on String {
+  void m() {}
+}
+''');
+    addTestFile('''
+part 'part.dart';
+void f(String s) {
+  s.^;
+}
+''');
+    await getSuggestions();
+    assertHasCompletion('m');
+  }
+
+  @failingTest
+  Future<void> test_explicitTarget_method_notImported() async {
+    // Available suggestions data doesn't yet have information about extension
+    // methods.
+    newFile(convertPath('/project/bin/lib.dart'), content: '''
+extension E on String {
+  void m() {}
+}
+''');
+    addTestFile('''
+void f(String s) {
+  s.^;
+}
+''');
+    await getSuggestions();
+    assertHasCompletion('m');
+  }
+
+  Future<void> test_explicitTarget_method_sameUnit() async {
+    addTestFile('''
+void f(String s) {
+  s.^;
+}
+extension E on String {
+  void m() {}
+}
+''');
+    await getSuggestions();
+    assertHasCompletion('m');
+  }
+
+  Future<void> test_explicitTarget_setter_sameUnit() async {
+    addTestFile('''
+void f(String s) {
+  s.^;
+}
+extension E on String {
+  set e(int v) {}
+}
+''');
+    await getSuggestions();
+    assertHasCompletion('e');
+  }
+
+  Future<void> test_implicitTarget_inClass_method_sameUnit() async {
+    addTestFile('''
+class C {
+  void c() {
+    ^
+  }
+}
+extension E on C {
+  void m() {}
+}
+''');
+    await getSuggestions();
+    assertHasCompletion('m');
+  }
+
+  Future<void> test_implicitTarget_inExtension_method_sameUnit() async {
+    addTestFile('''
+extension E on String {
+  void m() {
+    ^
+  }
+}
+''');
+    await getSuggestions();
+    assertHasCompletion('m');
+  }
+}
+
 @reflectiveTest
 class PropertyAccessorCompletionTest extends CompletionTestCase {
   Future<void> test_setter_deprecated() async {