These might be useful for a function with a more restricted domain. But for
equals, which accepts two of literally anything, the short run was too short
to catch any problems and the long run tended to exceed the CircleCi timeout.
Previously, a custom matcher library that wanted to remain compatible with
Jasmine <= 3.5.x could not know whether or not Jasmine expected it to pass
custom equality testers to MatchersUtil#contains. Passing them would produce
a deprecation warning in newer versions and not passing them would break
compatibility with older versions. Now we use matcher factory arity to
determine whether to pass custom equality testers to the factory, which
allows libraries to do something like this:
function matcherFactory(util) {
const customEqualityTesters = arguments[1];
// customEqualityTesters will be undefined in newer versions of Jasmine
// and defined in older versions that expect it to be passed back to
// MatchersUtil#equals.
}
* Include stack traces. This makes it easier to find the matcher that
needs to be updated, particularly when it comes from a library rather
than the user's own code.
* Show each deprecation only once unless `config.verboseDeprecations`
is set. Since matchers are often added in a global `beforeEach`, logging
deprecations every time can be overwhelming.
Custom object formatters allow users to customize how an object is
stringified in matcher failure messages. This can already be done by
adding a `jasmineToString` method to the objects in question. But
it's not always desirable or possible to do that, particularly when
objects of a given "type" do not inherit from a specific prototype.
For instance, suppose a web service returns a list of foos that are
deserialized from JSON, e.g.:
{ fooId: 42, /* more properties */ }
The only way to define `jasmineToString` on those is by writing code to
add it to each instance at runtime. But a custom object formatter can
recognize that the object it's looking at is a foo and format it
accordingly:
jasmine.addCustomObjectFormatter(function(obj) {
if (typeof obj.fooId !== 'number') {
return undefined;
}
return '[Foo with ID ' + obj.fooId + ']';
});
Unlike `jasmineToString`, custom object formatters are scoped to a
particular spec or suite and don't require any changes to the code
under test.
