Statement completion framework with a few examples

pkg/analysis_server/test/edit/statement_completion_test.dart

+// Copyright (c) 2017, 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.edit.statement_completion;
+
+import 'package:analysis_server/plugin/protocol/protocol.dart';
+import 'package:analysis_server/src/edit/edit_domain.dart';
+import 'package:plugin/manager.dart';
+import 'package:test/test.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../analysis_abstract.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(StatementCompletionTest);
+  });
+}
+
+@reflectiveTest
+class StatementCompletionTest extends AbstractAnalysisTest {
+  SourceChange change;
+
+  @override
+  void setUp() {
+    enableNewAnalysisDriver = true;
+    super.setUp();
+    createProject();
+    ExtensionManager manager = new ExtensionManager();
+    manager.processPlugins([server.serverPlugin]);
+    handler = new EditDomainHandler(server);
+  }
+
+  test_plainEnterFromStart() async {
+    addTestFile('''
+main() {
+  int v = 1;
+}
+''');
+    await waitForTasksFinished();
+    await _prepareCompletion('v = 1;', atStart: true);
+    _assertHasChange(
+        'Insert a newline at the end of the current line',
+        '''
+main() {
+  int v = 1;
+  /*caret*/
+}
+''');
+  }
+
+  test_plainOleEnter() async {
+    addTestFile('''
+main() {
+  int v = 1;
+}
+''');
+    await waitForTasksFinished();
+    await _prepareCompletion('v = 1;', atEnd: true);
+    _assertHasChange(
+        'Insert a newline at the end of the current line',
+        '''
+main() {
+  int v = 1;
+  /*caret*/
+}
+''');
+  }
+
+  test_plainOleEnterWithError() async {
+    addTestFile('''
+main() {
+  int v =
+}
+''');
+    await waitForTasksFinished();
+    String match = 'v =';
+    await _prepareCompletion(match, atEnd: true);
+    _assertHasChange(
+        'Insert a newline at the end of the current line',
+        '''
+main() {
+  int v =
+  x
+}
+''',
+        (s) => s.indexOf(match) + match.length); // Ensure cursor after '='.
+  }
+
+  void _assertHasChange(String message, String expectedCode, [Function cmp]) {
+    if (change.message == message) {
+      if (!change.edits.isEmpty) {
+        String resultCode =
+            SourceEdit.applySequence(testCode, change.edits[0].edits);
+        expect(resultCode, expectedCode.replaceAll('/*caret*/', ''));
+        if (cmp != null) {
+          int offset = cmp(resultCode);
+          expect(change.selection.offset, offset);
+        }
+      } else {
+        if (cmp != null) {
+          int offset = cmp(testCode);
+          expect(change.selection.offset, offset);
+        }
+      }
+      return;
+    }
+    fail("Expected to find |$message| but got: " + change.message);
+  }
+
+  _prepareCompletion(String search,
+      {bool atStart: false, bool atEnd: false, int delta: 0}) async {
+    int offset = findOffset(search);
+    if (atStart) {
+      delta = 0;
+    } else if (atEnd) {
+      delta = search.length;
+    }
+    await _prepareCompletionAt(offset + delta);
+  }
+
+  _prepareCompletionAt(int offset) async {
+    Request request =
+        new EditGetStatementCompletionParams(testFile, offset).toRequest('0');
+    Response response = await waitResponse(request);
+    var result = new EditGetStatementCompletionResult.fromResponse(response);
+    change = result.change;
+  }
+}