autotest

npm install @tim-code/autotest

A zero-dependency helper function to reduce boilerplate in writing Jest tests

Philosophy

import { autotest, factory } from "@tim-code/autotest"

autotest(functionToTest, options)(input1, input2, ...)(expected)

factory(options)(functionToTest)(input1, input2, ...)(expected)

Note expected itself can be a (async) callback. If so, autotest will pass the test output to it instead of using expect(output).toEqual(expected).

Similar Jest code for comparison:

test("functionToTest(...)", () => {
  expect(functionToTest(input1, input2, ...)).toEqual(expected)
})

Options

name: Name the test. Otherwise, try to make one from the test function's name and passed in input.

callbackName: If name is not specified, used instead of functionToTest.name to name the test.

error: Specify that an error is expected.

only: Use test.only to make only one test run, which is useful for debugging.

timeout: Specifies the max execution time for the test and is useful for debugging

setup: (async) callback that is always invoked with no arguments before the test is run; its return value has no effect

teardown: (async) callback that is always invoked with no arguments after all callbacks are run (or error); its return value has no effect

after: a (async) callback that is invoked with the test function output; its return value will be tested with/using expected

before:

This is a (async) callback that is invoked with the input before the test is run (but after setup). Its return value must be iterable and will be passed to the test callback via the spread operator. This can be useful for generating input to a test. For example:

const autotest = factory({ before: (add, multiple) => [add + Math.random() * multiple] })
autotest(handleOneToSix)(1, 5)(expected)
autotest(handleOneToEleven)(1, 10)(expected)

consume:

This is a (async) callback that is invoked with the test function and the input, which is useful for testing higher order functions.

const add = (x) => (y) => x + y
const autotest = factory({ consume: (func, [x, y]) => func(x)(y) })
const test = autotest(add)
test(1, 2)(3) // test name will be add(1,2), not add(1)(2)

For convenience, the above consume function is exported as consume2 with consume3 and consume4 analogs.

There is also consume2Iterables, consume3Iterables, and consume4Iterables exported which spread their input:

const add = (x) => (y) => (z) => x + y + z
const autotest = factory({ consume: consume3Iterables })
const test = autotest(add)
test([1], [2], [3])(6) // test name will be add([1],[2],[3]), not add([1])([2])([3])