Index: lib/unittest/expect.dart |
=================================================================== |
--- lib/unittest/expect.dart (revision 0) |
+++ lib/unittest/expect.dart (revision 0) |
@@ -0,0 +1,125 @@ |
+// 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. |
+ |
+/** |
+ * This is the main assertion function. It asserts that [actual] |
+ * matches the [matcher]. [reason] is optional and is typically |
+ * not supplied, as a reason can be generated from the matcher. |
+ * If [reason] is included it is appended to the reason generated |
+ * by the matcher. |
+ * |
+ * If the assertion fails, then the default behavior is to throw an |
+ * [ExpectException], but this behavior can be changed by calling |
+ * [configureExpectHandler] and providing an alternative handler that |
+ * implements the [IFailureHandler] interface. |
+ * |
+ * [expect] allows an alternative call format, providing a Boolean |
+ * predicate as the first argument and an optional reason as the |
+ * second argument. This supports brevity at the expense of detailed |
+ * error messages. For example, these are equivalent, but the first |
+ * form will give a detailed error message, while the second form will |
+ * just give a generic assertion failed message: |
+ * |
+ * expect(foo, isLessThanOrEqual(bar)); |
+ * expect(foo <= bar); |
+ * |
+ * expect() is a 3rd generation assertion mechanism, drawing |
+ * inspiration from [Hamcrest] and Ladislav Thon's [dart-matchers] |
+ * library. |
+ * |
+ * See [Hamcrest] http://en.wikipedia.org/wiki/Hamcrest |
+ * [Hamcrest] http://http://code.google.com/p/hamcrest/ |
+ * [dart-matchers] https://github.com/Ladicek/dart-matchers |
+ */ |
+void expect(actual, [matcherOrReason = null, String reason = '']) { |
+ if (matcherOrReason is Matcher) { |
+ var doesMatch; |
+ try { |
+ doesMatch = matcherOrReason.matches(actual); |
+ } catch (var e, var trace) { |
+ doesMatch = false; |
+ if (reason == '') { |
+ reason = '${(e is String) ? e : e.toString()} at $trace'; |
+ } |
+ } |
+ if (!doesMatch) { |
+ // Make sure we have a failure handler configured. |
+ configureExpectHandler(_assertFailureHandler); |
+ _assertFailureHandler.failMatch(actual, matcherOrReason, reason); |
+ } |
+ } else { |
+ if (!actual) { |
+ reason = (matcherOrReason == null) ? 'Assertion failed' : matcherOrReason; |
+ // Make sure we have a failure handler configured. |
+ configureExpectHandler(_assertFailureHandler); |
+ _assertFailureHandler.fail(reason); |
+ } |
+ } |
+} |
+ |
+/** |
+ * Takes an argument and returns an equivalent matcher. |
+ * If the argument is already a matcher this does nothing, else it |
+ * generates an equals matcher for the argument. |
+ */ |
+Matcher wrapMatcher(x) => ((x is Matcher) ? x : equals(x)); |
+ |
+// The handler for failed asserts. |
+FailureHandler _assertFailureHandler = null; |
+ |
+// The default failure handler that throws ExpectExceptions. |
+class DefaultFailureHandler implements FailureHandler { |
+ DefaultFailureHandler() { |
+ if (_assertErrorFormatter == null) { |
+ _assertErrorFormatter = _defaultErrorFormatter; |
+ } |
+ } |
+ void fail(String reason) { |
+ throw new ExpectException(reason); |
+ } |
+ void failMatch(actual, Matcher matcher, String reason) { |
+ fail(_assertErrorFormatter(actual, matcher, reason)); |
+ } |
+} |
+ |
+/** |
+ * Changes or resets to the default the failure handler for expect() |
+ * [handler] is a reference to the new handler; if this is omitted |
+ * or null then the failure handler is reset to the default, which |
+ * throws [ExpectExceptions] on [expect] assertion failures. |
+ */ |
+void configureExpectHandler([FailureHandler handler = null]) { |
+ if (handler == null) { |
+ handler = new DefaultFailureHandler(); |
+ } |
+ _assertFailureHandler = handler; |
+} |
+ |
+// The error message formatter for failed asserts. |
+ErrorFormatter _assertErrorFormatter = null; |
+ |
+// The default error formatter implementation. |
+String _defaultErrorFormatter(actual, Matcher matcher, String reason) { |
+ var description = new StringDescription(); |
+ description.add('Expected: ').addDescriptionOf(matcher). |
+ add('\n but: '); |
+ matcher.describeMismatch(actual, description); |
+ description.add('\n').add(reason).add('\n'); |
+ return description.toString(); |
+} |
+ |
+/** |
+ * Changes or resets to default the failure message formatter for expect(). |
+ * [formatter] is a reference to the new formatter; if this is omitted or |
+ * null then the failure formatter is reset to the default. The new |
+ * formatter is returned; this allows custom expect handlers to easily |
+ * get a reference to the default formatter. |
+ */ |
+ErrorFormatter configureExpectFormatter([ErrorFormatter formatter = null]) { |
+ if (formatter == null) { |
+ formatter = _defaultErrorFormatter; |
+ } |
+ return _assertErrorFormatter = formatter; |
+} |
+ |