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Rstest
Guide
Config
API
Guide
Config
API

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.

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