Issue 25252. Stop collecting covering expressions at void invocations.

pkg/analysis_server/test/services/refactoring/extract_local_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.services.refactoring.extract_local;
 
 import 'dart:async';
 import 'dart:convert';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
@@ skipping 132 matching lines @@
     _createRefactoringForString("c'");
     // apply refactoring
     return _assertSuccessfulRefactoring('''
 main() {
   var res = 'abc';
   var vvv = res;
 }
 ''');
   }
 
+  test_checkInitialConditions_voidExpression() async {
+    indexTestUnit('''
+main() {
+  print(42);
+}
+''');
+    _createRefactoringForString('print');
+    // check conditions
+    RefactoringStatus status = await refactoring.checkInitialConditions();
+    assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL,
+        expectedMessage: 'Cannot extract the void expression.');
+  }
+
   test_checkLocalName() {
     indexTestUnit('''
 main() {
   int a = 1 + 2;
 }
 ''');
     _createRefactoringForString('1 + 2');
     expect(refactoring.refactoringName, 'Extract Local Variable');
     // null
     refactoring.name = null;
@@ skipping 182 matching lines @@
 }
 int foo(int x) => x;
 ''');
     _createRefactoring(testCode.indexOf('11 +'), 0);
     // check conditions
     await refactoring.checkInitialConditions();
     List<String> subExpressions = _getCoveringExpressions();
     expect(subExpressions, ['111', '111 + 222', 'foo(111 + 222)']);
   }
 
+  test_coveringExpressions_inInvocationOfVoidFunction() async {
+    indexTestUnit('''
+main() {
+  foo(111 + 222);
+}
+void foo(int x) {}
+''');
+    _createRefactoring(testCode.indexOf('11 +'), 0);
+    // check conditions
+    await refactoring.checkInitialConditions();
+    List<String> subExpressions = _getCoveringExpressions();
+    expect(subExpressions, ['111', '111 + 222']);
+  }
+
   test_coveringExpressions_skipAssignments() async {
     indexTestUnit('''
 main() {
   int v;
   foo(v = 111 + 222);
 }
 int foo(x) => 42;
 ''');
     _createRefactoring(testCode.indexOf('11 +'), 0);
     // check conditions
@@ skipping 772 matching lines @@
   List<String> _getCoveringExpressions() {
     List<String> subExpressions = <String>[];
     for (int i = 0; i < refactoring.coveringExpressionOffsets.length; i++) {
       int offset = refactoring.coveringExpressionOffsets[i];
       int length = refactoring.coveringExpressionLengths[i];
       subExpressions.add(testCode.substring(offset, offset + length));
     }
     return subExpressions;
   }
 }