Tests should be living documentation for your code, but often test descriptions get out of sync with your code. This library helps keep them in sync using TypeScript.
- When you rename a class, the name of your test for it will automatically update
- When you rename any of the following, your test will get a TypeScript error until you update your test:
- A method on a class
- A field on a class
- An exported function inside a module
- Has useful functions for creating mocks:
partialOf<T>(partial: Partial<T>): TdeepPartialOf<T>(partial: DeepPartial<T>): T
npm install jest-helpers --save-dev./greeter.ts
export class Greeter {
getGreeting(name: string) {
return `Hello ${name}`;
}
}
export function showGreeting(greeter: Greeter, name: string) {
const greeting = greeter.getGreeting(name)
console.log(greeting)
}./greeter.test.ts
import { describeClass, describeFunction, describeMethod, partialOf } from 'jest-helpers';
import greeterModule = require('greeter');
import { Greeter, showGreeting } from './greeter';
describeClass(Greeter, () => {
describeMethod(Greeter, 'getGreeting', () => {
it('should return a personalised greeting', () => {
const greeter = new Greeter();
expect(greeter.getGreeting('Joe')).toEqual('Hello Joe');
});
});
});
describeFunction(greeterModule, 'showGreeting', () => {
it('should log greeting to the console', () => {
const greeterMock = partialOf<Greeter>({
getGreeting: jest.fn().mockReturnValue('yo!')
});
jest.spyOn(console, 'log');
showGreeting(greeterMock, 'Joe');
expect(greeterMock.getGreeting).toHaveBeenCalledWith('Joe');
expect(console.log).toHaveBeenCalledWith('yo!');
});
});Running jest --verbose will output something like
example/greeter.ts
Greeter
getGreeting
✓ should return a personalised greeting (4ms)
showGreeting
✓ should log greeting to the console (2ms)
If you rename your Greeter class, it will automatically update the test description.
If you rename your Greeter.getGreeting method, you will get a TypeScript error in your test until you update your test to match the new name.
If you rename your showGreeting function, you will get a TypeScript error in your test until you update your test to match the new name.
Got an issue or a feature request? Log it.
Pull-requests are also welcome. 😸
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