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 {
const 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)));
Constructors
- CustomMatcher(String _featureDescription, String _featureName, matcher)
Properties
- hashCode → int
-
Get a hash code for this object.
read-only, inherited - runtimeType → Type
-
A representation of the runtime type of the object.
read-only, inherited
Operators
-
operator ==(
other) → bool -
The equality operator.
inherited
Methods
-
describe(
Description description) → Description -
This builds a textual description of the matcher.
-
describeMismatch(
item, Description mismatchDescription, Map matchState, bool verbose) → Description -
This builds a textual description of a specific mismatch.
itemis the value that was tested bymatches;matchStateis theMapthat was passed to and supplemented bymatcheswith additional information about the mismatch, andmismatchDescriptionis theDescriptionthat is being built to decribe the mismatch. A few matchers make use of theverboseflag to provide detailed information that is not typically included but can be of help in diagnosing failures, such as stack traces. -
featureValueOf(
actual) → dynamic -
Override this to extract the interesting feature.
-
matches(
item, Map matchState) → bool -
This does the matching of the actual vs expected values.
itemis the actual value.matchStatecan be supplied and may be used to add details about the mismatch that are too costly to determine indescribeMismatch. -
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a non-existent method or property is accessed.
inherited -
toString(
) → String -
Returns a string representation of this object.
inherited