CustomMatcher class

A useful utility class for implementing other matchers through inheritance. Derived classes should call the base constructor with a feature name and description, and an instance matcher, and should implement the featureValueOf abstract method.

The feature description will typically describe the item and the feature, while the feature name will just name the feature. For example, we may have a Widget class where each Widget has a price; we could make a CustomMatcher that can make assertions about prices with:

class HasPrice extends CustomMatcher {
  HasPrice(matcher) : super("Widget with price that is", "price", matcher);
  featureValueOf(actual) => actual.price;

and then use this for example like:

expect(inventoryItem, new HasPrice(greaterThan(0)));


CustomMatcher(String _featureDescription, String _featureName, dynamic matcher)


hashCode int
The hash code for this object. [...]
read-only, inherited
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited


describe(Description description) Description
Builds a textual description of the matcher.
describeMismatch(dynamic item, Description mismatchDescription, Map matchState, bool verbose) Description
Builds a textual description of a specific mismatch. [...]
featureValueOf(dynamic actual) Object
Override this to extract the interesting feature.
matches(dynamic item, Map matchState) bool
Does the matching of the actual vs expected values. [...]
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed. [...]
toString() String
Returns a string representation of this object.


operator ==(dynamic other) bool
The equality operator. [...]