jest-test-each

jest-test-each

This package will help you to run parametrised tests easily [typesafe] without text tables or arrays of arrays.

Table of Contents

1. Examples
2. Setup
3. Features
4. What's next

Examples

You can see demo project here.

Tests are here.

Simple

its('roundings')
  .each([
    { input: 0, expected: '0' },
    { input: 0.99, expected: '1' },
    { input: 102.99998, expected: '103' },
    { input: -6, expected: '-6' },
  ])
  .run(t => {
    expect(Math.round(t.input).toFixed(0)).toBe(t.expected);
  });

Run test in idea with jest plugin:

More complex

its('check calculator')
  .each([
    { a: 1, b: 2, exp: [3, -1, 2, 0.5] },
    { a: 1, b: 0, exp: [1, 1, 0, Infinity] },
  ])
  .each(t => [
    { sign: '+' as const, exp: t.exp[0] },
    { sign: '-' as const, exp: t.exp[1] },
    { sign: '*' as const, exp: t.exp[2] },
    { sign: '/' as const, exp: t.exp[3] },
  ])
  .each(t => [{ flatDesc: `${t.a} ${t.sign} ${t.b} should be ${t.exp}` }])
  .run(async t => {
    expect(calc(t.a, t.b, t.sign)).toBe(t.exp);
  });

and the same test with auto cases names:

Setup

Install dev dependency:

yarn add -D jest-test-each

Add the following into your config setup.js file which is referred in jest.config.js - setupFilesAfterEnv section:

// Looking a way to improve this. Can anyone help ?)
require('jest-test-each');

for .ts tests to see globals 'its' and 'Test' add the following to your tsconfig:

// tsconfig.json
 "include": [
    ...
    "node_modules/jest-test-each/dist/index.d.ts"
  ]

Additional [optional]

You can override test runner environment (by default it is jest env) by the following:

TestEachEnv({
  describe: describe,
  it: it,
  beforeAll: beforeAll,
  ...
});

Features

• cases multiplication (.each().each()....run())
• ability to setup test-each (global setup or each test setup):
  • number suites/cases or not
  • group each level by suite or not
  • concurrent testing
  • max length of case name - on reaching it will ask to sepcify explicit description for case
• ability to setup test runner environment (by default it is jest)
• ability to specify description for each case as function depending on case args
• ability to create .each level depending on previous data
• ability to have flat tests cases (not groupped to suites) when each case has 'flatDesc'
• global var 'Test' (or 'its' alias) to access test each (I'm accepting suggestions on namings)
• ability to run without single .each (its('foo').run(..))
• To run one test from TestEach like it.only (.only(<filter>)) (example).
• ability to run '.before' in testEach with disposable interface for automatic cleanup (example).
• ability to skip test if it is marked with defect (example).
• added field 'actualFailReasonParts' for case - to fail when defected test fails with other reason than expected (example).
• '.ensure' to check cases match some condition (example).
• '.ensureCasesLength' to check cases length - in case when .each has dynamic args and you don't want to miss some tests (example).
• ability to skip test

.only() usage

See example.

Running the feature containing this will result in 2 tests

  its('Simple test: roundings')
    .each([
      { input: 0, expected: '0' },
      { input: 0.99, expected: '1' },
      { input: 102.99998, expected: '103' },
      { input: -6, expected: '-6' },
    ])
    .only(t => t.input === -6)
    .run(t => {
      expect(Math.round(t.input).toFixed(0)).toBe(t.expected);
    });

What's next

• do not create suite wrapping when resulted to only one test in the group

Unavailable features

1. to start testEach by Idea plugin (workaround: wrap with describe and do not put name into Test Each)