ts-stubber

!ts-stubber
!typescript
!Known Vulnerabilities

!Branches
!Functions
!Lines
!Statements
!Coverage total

A generic stubbed instance creator to lazy stub any interface/class, while completely avoiding calling class's constructor.
Thus, enabling both avoiding side effects that may occur while class constructor is activated and mocking Classes with no default constructor.

Documentation

Installation

npm i -D ts-stubber

or

yarn add -D ts-stubber

Usage

This library provides an API to create a stubbed instance of a class or interface, including property functions, allowing overrides of methods, setters and getters..

``ts
class MyClass {
constructor(input: number) {
throw new Error("Should not be called");
}
func(input: number, text: string) {
console.log(text);
return input;
}
property: number = 3;
optionalProperty?: number;
get getter(): number {
return this.property;
}
set setter(value: number) {
throw new Error("Should not be called");
}
}

// creating a stubbed instance using the native node:test module
const const nodeStubbedInstanceCreator = StubbedInstanceCreator>(
() => mock.fn()
);

const nodeMockMyClass = nodeStubbedInstanceCreator.createStubbedInstance();

// creating a stubbed instance using sinon
const sinonStubbedInstanceCreator = StubbedInstanceCreator(
() => sinon.stub()
);

const sinonMockMyClass = sinonStubbedInstanceCreator.createStubbedInstance();

// creating a stubbed instance using jest
const jestStubbedInstanceCreator = StubbedInstanceCreator(
() => jest.fn()
);

const jestMockMyClass = jestStubbedInstanceCreator.createStubbedInstance();
`

Caveats, Known Issues, and Limitations

Due to the lazy nature of the stubbing, for properties to exist in the stub, they must be overridden or set with a value.

`ts
class MyClass {
property: number = 3;
get getter(): number {
return this.property;
}
set setter(value: number) {
throw new Error("Should not be called");
}
}

it("should have own property given property is overridden", () => {
const mockMyClass = StubbedInstanceCreator(() =>
jest.fn()
).createStubbedInstance({ property: 5 }); // this test will fail if property is not overridden
expect((mockMyClass).hasOwnProperty("property")).toBe(true);
});

it("should have own property given property is set", () => {
const mockMyClass = StubbedInstanceCreator(() =>
jest.fn()
).createStubbedInstance();
mockMyClass.property = 8; // this test will fail if property is not set
expect((mockMyClass).hasOwnProperty("property")).toBe(true);
});
`

Testing

1. Set up the repo - yarn
2. Build the project - npm run build
3. Running Jest tests - npm run test
4. Running Cypress tests - npm run cy:run`

License

This project is licensed under the MIT License - see the LICENSE.md file for details