#Mock functions

Rstest provides some utility functions to help you mock functions powered by tinyspy.

#rstest.fn

• Type:

export interface Mock<T extends Function> extends MockInstance<T> {
  (...args: Parameters<T>): ReturnType<T>;
}

export type MockFn = <T extends Function>(fn?: T) => Mock<T>;

Creates a spy on a function.

const sayHi = rstest.fn((name: string) => `hi ${name}`);

const res = sayHi('bob');

expect(res).toBe('hi bob');

expect(sayHi).toHaveBeenCalledTimes(1);

#rstest.spyOn

• Type:

export type SpyFn = (
  obj: Record<string, any>,
  methodName: string,
  accessType?: 'get' | 'set',
) => MockInstance;

Creates a spy on a method of an object.

const sayHi = () => 'hi';
const hi = {
  sayHi,
};

const spy = rstest.spyOn(hi, 'sayHi');

expect(hi.sayHi()).toBe('hi');

expect(spy).toHaveBeenCalled();

#rstest.isMockFunction

• Type: (fn: any) => fn is MockInstance

Determines if the given function is a mocked function.

#rstest.clearAllMocks

• Type: () => Rstest

Clears the mock.calls, mock.instances, mock.contexts and mock.results properties of all mocks.

#rstest.resetAllMocks

• Type: () => Rstest

Clears all mocks properties and reset each mock's implementation to its original.

#rstest.restoreAllMocks

• Type: () => Rstest

Reset all mocks and restore original descriptors of spied-on objects.