Add incremental parser test for splitting a combinator.

pkg/analyzer/test/generated/parser_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 engine.parser_test;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/incremental_scanner.dart';
@@ skipping 2781 matching lines @@
     // "f() => a * c - b;"
     _assertParse("f() => a ", "+", "* c -", " b;");
   }
 
   void test_replace_operator_oneForOne() {
     // "f() => a + b;"
     // "f() => a * b;"
     _assertParse("f() => a ", "+", "*", " b;");
   }
 
+  void test_split_combinator() {
+    // "import 'foo.dart' show A;"
+    // "import 'foo.dart' show B hide A;"
+    _assertParse("import 'foo.dart' show ", "", "B hide ", "A;");
+  }
+
   /**
    * Given a description of the original and modified contents, perform an incremental scan of the
    * two pieces of text.
    *
    * @param prefix the unchanged text before the edit region
    * @param removed the text that was removed from the original contents
    * @param added the text that was added to the modified contents
    * @param suffix the unchanged text after the edit region
    */
   void _assertParse(String prefix, String removed, String added,
@@ skipping 8046 matching lines @@
     // Parse the source.
     //
     Parser parser = new Parser(null, listener);
     return invokeParserMethodImpl(
         parser,
         methodName,
         <Object>[tokenStream],
         tokenStream) as Token;
   }
 }