Check for one-to-many source mappings.

pkg/js_ast/test/printer_callback_test.dart

 // Copyright (c) 2015, 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.
 
 // Note: This test relies on LF line endings in the source file.
 
 // Test that JS printer callbacks occur when expected.
 
 library js_ast.printer.callback_test;
 
@@ skipping 143 matching lines @@
   [1,, 2];
 @0}""",
    TestMode.EXIT: """
 function() {
   a@4.b@5@3;
 @2  [1@8,,@9 2@10]@7;
 @6}@1@0""",
   }),
 
   const TestCase(const {
-    TestMode.INPUT: "a.#nameTemplate",
-    TestMode.NONE: "a.nameValue",
-    TestMode.ENTER: "@0@1a.@2nameValue",
-    TestMode.DELIMITER: "a.nameValue",
-    TestMode.EXIT: "a@1.nameValue@2@0",
+    TestMode.INPUT: "a.#nameTemplate = #nameTemplate",
+    TestMode.NONE: "a.nameValue = nameValue",
+    TestMode.ENTER: "@0@1@2a.@3nameValue = @3nameValue",
+    TestMode.DELIMITER: "a.nameValue = nameValue",
+    TestMode.EXIT: "a@2.nameValue@3@1 = nameValue@3@0",
   }, const {'nameTemplate': 'nameValue'}),
 ];
 
 class FixedName extends Name {
   final String name;
   String get key => name;
 
   FixedName(this.name);
 
   @override
@@ skipping 68 matching lines @@
     if (offset < text.length) {
       sb.write(text.substring(offset));
     }
     return sb.toString();
   }
 }
 
 void main() {
   DATA.forEach(check);
 }