Change output of string equality match failures.

pkg/unittest/lib/src/basematcher.dart

 // Copyright (c) 2012, 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.
 
 part of matcher;
 
 /**
  * MatchState is a simple wrapper around an arbitrary object.
  * [Matcher] [matches] methods can use this to store useful
  * information upon match failures, and this information will
@@ skipping 13 matching lines @@
 /**
  * BaseMatcher is the base class for all matchers. To implement a new
  * matcher, either add a class that implements Matcher or a class that
  * extends BaseMatcher. Extending BaseMatcher has the benefit that a
  * default implementation of describeMismatch will be provided.
  */
 abstract class BaseMatcher implements Matcher {
   const BaseMatcher();
 
   /**
+   * Whether failures should include the actual value in the output.
+   * The reason is passed in so that it can be inspected if necessary
+   * for some more complex cases.
+   */
+  bool includeActual(reason) => !reason.toString().startsWith('was ');

[Siggi Cherem (dart-lang), 2013/05/23 00:43:47]

2 comments:
a) how about storing a boolean property in your matcher instead? In the end it
is the same instance of this class that will print the mismatch.


b) rename to phrase it as a question or a statement. Ideas:
 - "includesActual" (see the extra 's'), which would mean the opposite of what
your method currently does.
 - "shouldIncludeActual"

I prefer the former, since it better represents a property of this object.

+
+
+  /**
    * Tests the matcher against a given [item]
    * and return true if the match succeeds; false otherwise.
    * [matchState] may be used to return additional info for
    * the use of [describeMismatch].
    */
   bool matches(item, MatchState matchState);
 
   /**
    * Creates a textual description of a matcher,
    * by appending to [mismatchDescription].
    */
   Description describe(Description mismatchDescription);
 
   /**
    * Generates a description of the matcher failed for a particular
    * [item], by appending the description to [mismatchDescription].
    * It does not check whether the [item] fails the match, as it is
    * only called after a failed match. There may be additional info
    * about the mismatch in [matchState].
    */
   Description describeMismatch(item, Description mismatchDescription,
                                MatchState matchState, bool verbose) =>
     mismatchDescription.add('was ').addDescriptionOf(item);
 }