New expectation functions plus convert old tests to use these.

lib/unittest/interfaces.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.
+
+// To decouple the reporting of errors, and allow for extensibility of
+// matchers, we make use of some interfaces.
+
+/**
+ * The IErrorFormatter interface is implemented by classes that
+ * can be used to build up error reports upon expect() failures.

[Bob Nystrom, 2012/05/30 23:23:51]

Square brackets around [expect()], [StringDescription].

+ * There is one built-in implementation (StringDescription) which
+ * is used by the default failure handler. If the failure handler
+ * is replaced it may be desirable to replace the StringDescription
+ * error description formatter with another; this can be done
+ * by implementing this interface.
+ */
+interface IErrorFormatter {
+  String format(actual, IMatcher matcher, String reason);

[Bob Nystrom, 2012/05/30 23:23:51]

Should this just be a function type? Why make it an interface?

[gram, 2012/06/01 17:33:15]

Done.

+}
+
+/**
+ * Matchers build up their error messages by appending to
+ * IDescription objects. This interface is also implemented
+ * by StringDescription. This interface is unlikely to need
+ * other implementations, but could be useful to replace in
+ * some cases - e.g. language conversion.
+ */
+interface IDescription {
+  IDescription append(text);

[Bob Nystrom, 2012/05/30 23:23:51]

"append" -> "add"

[gram, 2012/06/01 17:33:15]

Done.

+  IDescription appendDescriptionOf(value);
+  IDescription appendList(start, separator, end, list);

[Bob Nystrom, 2012/05/30 23:23:51]

Can these be typed?

[gram, 2012/06/01 17:33:15]

Done.

+}
+
+/**
+ * Matchers must implement the IMatcher interface. There
+ * are three methods: match, which does the matching;

[Bob Nystrom, 2012/05/30 23:23:51]

Instead of describing the methods here, just put comments with the methods.

[gram, 2012/06/01 17:33:15]

Done.

+ * describe, which builds a description of the matcher,
+ * and describeMismatch, which builds a description of
+ * a specific mismatch. The base Matcher class that implements
+ * this interface has a generic implementation of
+ * describeMismatch so this does not need to be provided
+ * unless a more clear description is required. The other
+ * two methods must always be provided as they are highly
+ * matcher-specific.
+ */
+interface IMatcher {
+  bool matches(item);
+  IDescription describe(IDescription description);
+  IDescription describeMismatch(item, IDescription mismatchDescription);
+}
+
+/**
+ * Failed matches are reported using a default IFailureHandler.
+ * The default implementation simply throws ExpectExceptions;
+ * this can be replaced by some other implementation of
+ * IFailureHandler by calling configureExpectHandler.
+ */
+interface IFailureHandler {
+  void fail(String reason);
+  void failMatch(actual, IMatcher matcher, String reason);
+}
+