Remove unittest and matcher from the repo.

pkg/matcher/lib/src/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.
-
-library matcher.interfaces;
-
-// To decouple the reporting of errors, and allow for extensibility of
-// matchers, we make use of some interfaces.
-
-/// 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 mismatch, 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;
-}