| // 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. |
| |
| library matcher.interfaces; |
| |
| // To decouple the reporting of errors, and allow for extensibility of |
| // matchers, we make use of some interfaces. |
| |
| /// The ErrorFormatter type is used for functions that |
| /// can be used to build up error reports upon [expect] failures. |
| /// There is one built-in implementation ([defaultErrorFormatter]) |
| /// which is used by the default failure handler. If the failure handler |
| /// is replaced it may be desirable to replace the [stringDescription] |
| /// error formatter with another. |
| typedef String ErrorFormatter(actual, Matcher matcher, String reason, |
| Map matchState, bool verbose); |
| |
| /// Matchers build up their error messages by appending to |
| /// Description objects. This interface is implemented by |
| /// StringDescription. This interface is unlikely to need |
| /// other implementations, but could be useful to replace in |
| /// some cases - e.g. language conversion. |
| abstract class Description { |
| int get length; |
| |
| /// Change the value of the description. |
| Description replace(String text); |
| |
| /// This is used to add arbitrary text to the description. |
| Description add(String text); |
| |
| /// This is used to add a meaningful description of a value. |
| Description addDescriptionOf(value); |
| |
| /// This is used to add a description of an [Iterable] [list], |
| /// with appropriate [start] and [end] markers and inter-element [separator]. |
| Description addAll(String start, String separator, String end, Iterable list); |
| } |
| |
| /// [expect] Matchers must implement/extend the Matcher class. |
| /// The base Matcher class 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 ([matches] and [describe]) |
| /// must always be provided as they are highly matcher-specific. |
| abstract class Matcher { |
| const Matcher(); |
| |
| /// This does the matching of the actual vs expected values. |
| /// [item] is the actual value. [matchState] can be supplied |
| /// and may be used to add details about the mismatch that are too |
| /// costly to determine in [describeMismatch]. |
| bool matches(item, Map matchState); |
| |
| /// This builds a textual description of the matcher. |
| Description describe(Description description); |
| |
| /// This builds a textual description of a specific mismatch. [item] |
| /// is the value that was tested by [matches]; [matchState] is |
| /// the [Map] that was passed to and supplemented by [matches] |
| /// with additional information about the mismact, and [mismatchDescription] |
| /// is the [Description] that is being built to decribe the mismatch. |
| /// A few matchers make use of the [verbose] flag to provide detailed |
| /// information that is not typically included but can be of help in |
| /// diagnosing failures, such as stack traces. |
| Description describeMismatch(item, Description mismatchDescription, |
| Map matchState, bool verbose) => mismatchDescription; |
| } |
| |
| /// Failed matches are reported using a default IFailureHandler. |
| /// The default implementation simply throws [TestFailure]s; |
| /// this can be replaced by some other implementation of |
| /// IFailureHandler by calling configureExpectHandler. |
| abstract class FailureHandler { |
| /// This handles failures given a textual decription |
| void fail(String reason); |
| |
| /// This handles failures given the actual [value], the [matcher] |
| /// the [reason] (argument from [expect]), some additonal [matchState] |
| /// generated by the [matcher], and a verbose flag which controls in |
| /// some cases how much [matchState] information is used. It will use |
| /// these to create a detailed error message (typically by calling |
| /// an [ErrorFormatter]) and then call [fail] with this message. |
| void failMatch(actual, Matcher matcher, String reason, |
| Map matchState, bool verbose); |
| } |