Add special completion for control-flow block exits

pkg/analysis_server/test/services/completion/statement/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.services.completion.statement;
 
 import 'package:analysis_server/src/protocol_server.dart';
 import 'package:analysis_server/src/services/completion/statement/statement_completion.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../../../abstract_single_unit.dart';
 
 main() {
   defineReflectiveSuite(() {
+    defineReflectiveTests(_ControlFlowCompletionTest);
     defineReflectiveTests(_DoCompletionTest);
     defineReflectiveTests(_ForCompletionTest);
     defineReflectiveTests(_ForEachCompletionTest);
     defineReflectiveTests(_IfCompletionTest);
     defineReflectiveTests(_SimpleCompletionTest);
     defineReflectiveTests(_SwitchCompletionTest);
     defineReflectiveTests(_TryCompletionTest);
     defineReflectiveTests(_WhileCompletionTest);
   });
 }
@@ skipping 59 matching lines @@
   }
 
   _prepareCompletionAt(int offset, String sourceCode) async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit(sourceCode);
     await _computeCompletion(offset);
   }
 }
 
 @reflectiveTest
+class _ControlFlowCompletionTest extends StatementCompletionTest {
+  test_doReturnExprLineComment() async {
+    await _prepareCompletion(
+        'return 3',
+        '''
+ex(e) {
+  do {
+    return 3//
+  } while (true);
+}
+''',
+        atEnd: true);
+    _assertHasChange(
+        'Complete control flow block',
+        '''
+ex(e) {
+  do {
+    return 3;//
+  } while (true);
+  ////
+}
+''',
+        (s) => _afterLast(s, '  '));
+  }
+
+  test_doReturnUnterminated() async {
+    await _prepareCompletion(
+        'return',
+        '''
+ex(e) {
+  do {
+    return
+  } while (true);
+}
+''',
+        atEnd: true);
+    _assertHasChange(
+        'Complete control flow block',
+        '''
+ex(e) {
+  do {
+    return;
+  } while (true);
+  ////
+}
+''',
+        (s) => _afterLast(s, '  '));
+  }
+
+  test_forEachReturn() async {
+    await _prepareCompletion(
+        'return;',
+        '''
+ex(e) {
+  for (var x in e) {
+    return;
+  }
+}
+''',
+        atEnd: true);
+    _assertHasChange(
+        'Complete control flow block',
+        '''
+ex(e) {
+  for (var x in e) {
+    return;
+  }
+  ////
+}
+''',
+        (s) => _afterLast(s, '  '));
+  }
+
+  test_forThrowUnterminated() async {
+    await _prepareCompletion(
+        'throw e',
+        '''
+ex(e) {
+  for (int i = 0; i < 3; i++) {
+    throw e
+  }
+}
+''',
+        atEnd: true);
+    _assertHasChange(
+        'Complete control flow block',
+        '''
+ex(e) {
+  for (int i = 0; i < 3; i++) {
+    throw e;
+  }
+  ////
+}
+''',
+        (s) => _afterLast(s, '  '));
+  }
+
+  test_ifThrow() async {
+    await _prepareCompletion(
+        'throw e;',
+        '''
+ex(e) {
+  if (true) {
+    throw e;
+  }
+}
+''',
+        atEnd: true);
+    _assertHasChange(
+        'Complete control flow block',
+        '''
+ex(e) {
+  if (true) {
+    throw e;
+  }
+  ////
+}
+''',
+        (s) => _afterLast(s, '  '));
+  }
+
+  test_ifThrowUnterminated() async {
+    await _prepareCompletion(
+        'throw e',
+        '''
+ex(e) {
+  if (true) {
+    throw e
+  }
+}
+''',
+        atEnd: true);
+    _assertHasChange(
+        'Complete control flow block',
+        '''
+ex(e) {
+  if (true) {
+    throw e;
+  }
+  ////
+}
+''',
+        (s) => _afterLast(s, '  '));
+  }

[Brian Wilkerson, 2017/04/21 21:45:45]

Would it be useful to have a test like

if (true) return

+
+  test_whileReturnExpr() async {
+    await _prepareCompletion(
+        '+ 4',
+        '''
+ex(e) {
+  while (true) {
+    return 3 + 4
+  }
+}
+''',
+        atEnd: true);
+    _assertHasChange(
+        'Complete control flow block',
+        '''
+ex(e) {
+  while (true) {
+    return 3 + 4;
+  }
+  ////
+}
+''',
+        (s) => _afterLast(s, '  '));
+  }
+}
+
+@reflectiveTest
 class _DoCompletionTest extends StatementCompletionTest {
   test_emptyCondition() async {
     await _prepareCompletion(
         'while ()',
         '''
 main() {
   do {
   } while ()
 }
 ''',
@@ skipping 787 matching lines @@
         '''
 main() {
   while () {
     ////
   }
 }
 ''',
         (s) => _after(s, 'while ('));
   }
 }