failsAssert function
Matcher that can be used in a test that expects an assertion error.
This is similar to standard throwsAssertionError
matcher, but also
allows an optional message string to verify that the assertion has the
expected message.
For example:
expect(
() => PositionComponent(size: Vector2.all(-1)),
failsAssert('size of a PositionComponent cannot be negative'),
)
Implementation
Matcher failsAssert([String? message]) {
var typeMatcher = isA<AssertionError>();
if (message != null) {
typeMatcher = typeMatcher.having((e) => e.message, 'message', message);
}
return throwsA(typeMatcher);
}