This is a fork of https://github.com/NagRock/ts-mockito. We hope to eventually re-merge and publish as ts-mockito.
Mocking library for TypeScript inspired by http://mockito.org/
- Strongly typed
- IDE autocomplete
- Mock creation (
mock) (also abstract classes) #example - Spying on real objects (
spy) #example - Changing mock behavior (
when) via: - Checking if methods were called with given arguments (
verify) - Resetting mock (
reset,resetCalls) #example, #example - Capturing arguments passed to method (
capture) #example - Recording multiple behaviors #example
- Readable error messages (ex.
'Expected "convertNumberToString(strictEqual(3))" to be called 2 time(s). But has been called 1 time(s).')
npm install @typestrong/ts-mockito --save-dev
// Creating mock let mockedFoo:Foo = mock(Foo); // Getting instance from mock let foo:Foo = instance(mockedFoo); // Using instance in source code foo.getBar(3); foo.getBar(5); // Explicit, readable verification verify(mockedFoo.getBar(3)).called(); verify(mockedFoo.getBar(anything())).called();// Creating mock let mockedFoo:Foo = mock(Foo); // stub method before execution when(mockedFoo.getBar(3)).thenReturn('three'); // Getting instance let foo:Foo = instance(mockedFoo); // prints three console.log(foo.getBar(3)); // prints null, because "getBar(999)" was not stubbed console.log(foo.getBar(999));// Creating mock let mockedFoo:Foo = mock(Foo); // stub getter before execution when(mockedFoo.sampleGetter).thenReturn('three'); // Getting instance let foo:Foo = instance(mockedFoo); // prints three console.log(foo.sampleGetter);Syntax is the same as with getter values.
Please note, that stubbing properties that don't have getters only works if Proxy object is available (ES6).
// Creating mock let mockedFoo:Foo = mock(Foo); // Getting instance let foo:Foo = instance(mockedFoo); // Some calls foo.getBar(1); foo.getBar(2); foo.getBar(2); foo.getBar(3); // Call count verification verify(mockedFoo.getBar(1)).once(); // was called with arg === 1 only once verify(mockedFoo.getBar(2)).twice(); // was called with arg === 2 exactly two times verify(mockedFoo.getBar(between(2, 3))).thrice(); // was called with arg between 2-3 exactly three times verify(mockedFoo.getBar(anyNumber()).times(4); // was called with any number arg exactly four times verify(mockedFoo.getBar(2)).atLeast(2); // was called with arg === 2 min two times verify(mockedFoo.getBar(anything())).atMost(4); // was called with any argument max four times verify(mockedFoo.getBar(4)).never(); // was never called with arg === 4// Creating mock let mockedFoo:Foo = mock(Foo); let mockedBar:Bar = mock(Bar); // Getting instance let foo:Foo = instance(mockedFoo); let bar:Bar = instance(mockedBar); // Some calls foo.getBar(1); bar.getFoo(2); // Call order verification verify(mockedFoo.getBar(1)).calledBefore(mockedBar.getFoo(2)); // foo.getBar(1) has been called before bar.getFoo(2) verify(mockedBar.getFoo(2)).calledAfter(mockedFoo.getBar(1)); // bar.getFoo(2) has been called before foo.getBar(1) verify(mockedFoo.getBar(1)).calledBefore(mockedBar.getFoo(999999)); // throws error (mockedBar.getFoo(999999) has never been called)let mockedFoo:Foo = mock(Foo); when(mockedFoo.getBar(10)).thenThrow(new Error('fatal error')); let foo:Foo = instance(mockedFoo); try { foo.getBar(10); } catch (error:Error) { console.log(error.message); // 'fatal error' }You can also stub method with your own implementation
let mockedFoo:Foo = mock(Foo); let foo:Foo = instance(mockedFoo); when(mockedFoo.sumTwoNumbers(anyNumber(), anyNumber())).thenCall((arg1:number, arg2:number) => { return arg1 * arg2; }); // prints '50' because we've changed sum method implementation to multiply! console.log(foo.sumTwoNumbers(5, 10));You can also stub method to resolve / reject promise
let mockedFoo:Foo = mock(Foo); when(mockedFoo.fetchData("a")).thenResolve({id: "a", value: "Hello world"}); when(mockedFoo.fetchData("b")).thenReject(new Error("b does not exist"));You can reset just mock call counter
// Creating mock let mockedFoo:Foo = mock(Foo); // Getting instance let foo:Foo = instance(mockedFoo); // Some calls foo.getBar(1); foo.getBar(1); verify(mockedFoo.getBar(1)).twice(); // getBar with arg "1" has been called twice // Reset mock resetCalls(mockedFoo); // Call count verification verify(mockedFoo.getBar(1)).never(); // has never been called after resetYou can also reset calls of multiple mocks at once resetCalls(firstMock, secondMock, thirdMock)
Or reset mock call counter with all stubs
// Creating mock let mockedFoo:Foo = mock(Foo); when(mockedFoo.getBar(1)).thenReturn("one"). // Getting instance let foo:Foo = instance(mockedFoo); // Some calls console.log(foo.getBar(1)); // "one" - as defined in stub console.log(foo.getBar(1)); // "one" - as defined in stub verify(mockedFoo.getBar(1)).twice(); // getBar with arg "1" has been called twice // Reset mock reset(mockedFoo); // Call count verification verify(mockedFoo.getBar(1)).never(); // has never been called after reset console.log(foo.getBar(1)); // null - previously added stub has been removedYou can also reset multiple mocks at once reset(firstMock, secondMock, thirdMock)
let mockedFoo:Foo = mock(Foo); let foo:Foo = instance(mockedFoo); // Call method foo.sumTwoNumbers(1, 2); // Check first arg captor values const [firstArg, secondArg] = capture(mockedFoo.sumTwoNumbers).last(); console.log(firstArg); // prints 1 console.log(secondArg); // prints 2You can also get other calls using first(), second(), byCallIndex(3) and more...
You can set multiple returning values for same matching values
const mockedFoo:Foo = mock(Foo); when(mockedFoo.getBar(anyNumber())).thenReturn('one').thenReturn('two').thenReturn('three'); const foo:Foo = instance(mockedFoo); console.log(foo.getBar(1));// one console.log(foo.getBar(1));// two console.log(foo.getBar(1));// three console.log(foo.getBar(1));// three - last defined behavior will be repeated infinitelyAnother example with specific values
let mockedFoo:Foo = mock(Foo); when(mockedFoo.getBar(1)).thenReturn('one').thenReturn('another one'); when(mockedFoo.getBar(2)).thenReturn('two'); let foo:Foo = instance(mockedFoo); console.log(foo.getBar(1));// one console.log(foo.getBar(2));// two console.log(foo.getBar(1));// another one console.log(foo.getBar(1));// another one - this is last defined behavior for arg '1' so it will be repeated console.log(foo.getBar(2));// two console.log(foo.getBar(2));// two - this is last defined behavior for arg '2' so it will be repeatedShort notation:
const mockedFoo:Foo = mock(Foo); // You can specify return values as multiple thenReturn args when(mockedFoo.getBar(anyNumber())).thenReturn('one', 'two', 'three'); const foo:Foo = instance(mockedFoo); console.log(foo.getBar(1));// one console.log(foo.getBar(1));// two console.log(foo.getBar(1));// three console.log(foo.getBar(1));// three - last defined behavior will be repeated infinityPossible errors:
const mockedFoo:Foo = mock(Foo); // When multiple matchers, matches same result: when(mockedFoo.getBar(anyNumber())).thenReturn('one'); when(mockedFoo.getBar(3)).thenReturn('one'); const foo:Foo = instance(mockedFoo); foo.getBar(3); // MultipleMatchersMatchSameStubError will be thrown, two matchers match same method callYou can mock interfaces too, just instead of passing type to mock function, set mock function generic type Mocking interfaces requires Proxy implementation
let mockedFoo:Foo = mock<FooInterface>(); // instead of mock(FooInterface) const foo: SampleGeneric<FooInterface> = instance(mockedFoo);You can mock abstract classes
const mockedFoo: SampleAbstractClass = mock(SampleAbstractClass); const foo: SampleAbstractClass = instance(mockedFoo);You can also mock generic classes, but note that generic type is just needed by mock type definition
const mockedFoo: SampleGeneric<SampleInterface> = mock(SampleGeneric); const foo: SampleGeneric<SampleInterface> = instance(mockedFoo);You can partially mock an existing instance:
const foo: Foo = new Foo(); const spiedFoo = spy(foo); when(spiedFoo.getBar(3)).thenReturn('one'); console.log(foo.getBar(3)); // 'one' console.log(foo.getBaz()); // call to a real methodYou can spy on plain objects too:
const foo = { bar: () => 42 }; const spiedFoo = spy(foo); foo.bar(); console.log(capture(spiedFoo.bar).last()); // [42] - Szczepan Faber (https://www.linkedin.com/in/szczepiq)
- Sebastian Konkol (https://www.linkedin.com/in/sebastiankonkol)
- Clickmeeting (http://clickmeeting.com)
- Michał Stocki (https://github.com/michalstocki)
- Łukasz Bendykowski (https://github.com/viman)
- Andrey Ermakov (https://github.com/dreef3)
- Markus Ende (https://github.com/Markus-Ende)
- Thomas Hilzendegen (https://github.com/thomashilzendegen)
- Johan Blumenberg (https://github.com/johanblumenberg)