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hooks.test.js
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hooks.test.js
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/* global test jest expect */
const {
withHookBefore,
withHookAfter,
hookArgs,
hookOutput
} = require('./hooks')
test('withHookBefore', () => {
const fn = jest.fn(() => {})
const hookedFn = withHookBefore(fn, function () {
expect(fn.mock.calls.length).toEqual(0)
})
hookedFn()
expect(fn.mock.calls.length).toEqual(1)
const interceptedFn = withHookBefore(fn, function () {
expect(fn.mock.calls.length).toEqual(1)
return false
})
interceptedFn()
expect(fn.mock.calls.length).toEqual(1)
})
test('withHookAfter', () => {
const fn = jest.fn(() => 123)
const hookedFn = withHookAfter(fn, function () {
expect(fn.mock.calls.length).toEqual(1)
})
expect(fn.mock.calls.length).toEqual(0)
expect(hookedFn()).toEqual(123)
})
test('hookArgs', () => {
const fn = jest.fn((a, b) => a + b + 1)
const validHookedFn = hookArgs(fn, (a, b) => [a + 1, b + 1])
expect(validHookedFn(0, 0)).toEqual(3)
const invalidHookedFn = hookArgs(fn, () => null)
expect(invalidHookedFn(0, 0)).toEqual(1)
})
test('hookOutput', () => {
const fn = jest.fn(x => x)
const hookedFn = hookOutput(fn, x => x + 1)
expect(hookedFn(0)).toEqual(1)
})