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jest-each has a new home over in core Jest πŸŽ‰

From Jest >=23 jest-each is available natively with test.each and describe.each see docs here

If you are using an older version of Jest I am still maintaining jest-each over in the core repo so you can still use jest-each in the exact same way as normal 😊

jest-each

Jest Parameterised Testing

Build Status Code Coverage version downloads MIT License PRs Welcome Examples

A parameterised testing library for Jest inspired by mocha-each.

jest-each allows you to provide multiple arguments to your test/describe which results in the test/suite being run once per row of parameters.

Features

  • .test to runs multiple tests with parameterised data
    • Also under the alias: .it
  • .test.only to only run the parameterised tests
    • Also under the aliases: .it.only or .fit
  • .test.skip to skip the parameterised tests
    • Also under the aliases: .it.skip or .xit or .xtest
  • .describe to runs test suites with parameterised data
  • .describe.only to only run the parameterised suite of tests
    • Also under the aliases: .fdescribe
  • .describe.skip to skip the parameterised suite of tests
    • Also under the aliases: .xdescribe
  • Asynchronous tests with done
  • Unique test titles with: sprintf
  • πŸ–– Spock like data tables with Tagged Template Literals

Demo

Tests without jest-each

Current jest tests

Tests can be re-written with jest-each to:

.test

Current jest tests

.test with Tagged Template Literals

Current jest tests

.describe

Current jest tests

Installation

npm i --save-dev jest-each

yarn add -D jest-each

Importing

jest-each is a default export so it can be imported with whatever name you like.

// es6
import each from 'jest-each';

// es5
const each = require('jest-each');

Array of rows

API

each([parameters]).test(name, testFn)

each:
  • parameters: Array of Arrays with the arguments that are passed into the testFn for each row
.test:
  • name: String the title of the test, use %s in the name string to positionally inject parameter values into the test title
  • testFn: Function the test logic, this is the function that will receive the parameters of each row as function arguments

each([parameters]).describe(name, suiteFn)

each:
  • parameters: Array of Arrays with the arguments that are passed into the suiteFn for each row
.describe:
  • name: String the title of the describe, use %s in the name string to positionally inject parameter values into the suite title
  • suiteFn: Function the suite of test/its to be ran, this is the function that will receive the parameters in each row as function arguments

Usage

.test(name, fn)

Alias: .it(name, fn)

each([
  [1, 1, 2],
  [1, 2, 3],
  [2, 1, 3],
]).test('returns the result of adding %s to %s', (a, b, expected) => {
  expect(a + b).toBe(expected);
});

.test.only(name, fn)

Aliases: .it.only(name, fn) or .fit(name, fn)

each([
  [1, 1, 2],
  [1, 2, 3],
  [2, 1, 3],
]).test.only('returns the result of adding %s to %s', (a, b, expected) => {
  expect(a + b).toBe(expected);
});

.test.skip(name, fn)

Aliases: .it.skip(name, fn) or .xit(name, fn) or .xtest(name, fn)

each([
  [1, 1, 2]
  [1, 2, 3],
  [2, 1, 3],
]).test.skip('returns the result of adding %s to %s', (a, b, expected) => {
  expect(a + b).toBe(expected);
});

Asynchronous .test(name, fn(done))

Alias: .it(name, fn(done))

each([
  ['hello'],
  ['mr'],
  ['spy'],
]).test('gives 007 secret message ', (str, done) => {
  const asynchronousSpy = (message) => {
    expect(message).toBe(str);
    done();
  };
  callSomeAsynchronousFunction(asynchronousSpy)(str);
});

.describe(name, fn)

each([
  [1, 1, 2],
  [1, 2, 3],
  [2, 1, 3],
]).describe('.add(%s, %s)', (a, b, expected) => {
  test(`returns ${expected}`, () => {
    expect(a + b).toBe(expected);
  });

  test('does not mutate first arg', () => {
    a + b;
    expect(a).toBe(a);
  });

  test('does not mutate second arg', () => {
    a + b;
    expect(b).toBe(b);
  });
});

.describe.only(name, fn)

Aliases: .fdescribe(name, fn)

each([
  [1, 1, 2],
  [1, 2, 3],
  [2, 1, 3],
]).describe.only('.add(%s, %s)', (a, b, expected) => {
  test(`returns ${expected}`, () => {
    expect(a + b).toBe(expected);
  });
});

.describe.skip(name, fn)

Aliases: .xdescribe(name, fn)

each([
  [1, 1, 2],
  [1, 2, 3],
  [2, 1, 3],
]).describe.skip('.add(%s, %s)', (a, b, expected) => {
  test(`returns ${expected}`, () => {
    expect(a + b).toBe(expected);
  });
});

Tagged Template Literal of rows

API

each[tagged template].test(name, suiteFn)

each`
  a    | b    | expected
  ${1} | ${1} | ${2}
  ${1} | ${2} | ${3}
  ${2} | ${1} | ${3}
`.test('returns $expected when adding $a to $b', ({ a, b, expected }) => {
  expect(a + b).toBe(expected);
});
each takes a tagged template string with:
  • First row of variable name column headings seperated with |
  • One or more subsequent rows of data supplied as template literal expressions using ${value} syntax.
.test:
  • name: String the title of the test, use $variable in the name string to inject test values into the test title from the tagged template expressions
  • testFn: Function the test logic, this is the function that will receive the parameters of each row as function arguments

each[tagged template].describe(name, suiteFn)

each`
  a    | b    | expected
  ${1} | ${1} | ${2}
  ${1} | ${2} | ${3}
  ${2} | ${1} | ${3}
`.describe('$a + $b', ({ a, b, expected }) => {
  test(`returns ${expected}`, () => {
    expect(a + b).toBe(expected);
  });

  test('does not mutate first arg', () => {
    a + b;
    expect(a).toBe(a);
  });

  test('does not mutate second arg', () => {
    a + b;
    expect(b).toBe(b);
  });
});
each takes a tagged template string with:
  • First row of variable name column headings seperated with |
  • One or more subsequent rows of data supplied as template literal expressions using ${value} syntax.
.describe:
  • name: String the title of the test, use $variable in the name string to inject test values into the test title from the tagged template expressions
  • suiteFn: Function the suite of test/its to be ran, this is the function that will receive the parameters in each row as function arguments

Usage

.test(name, fn)

Alias: .it(name, fn)

each`
  a    | b    | expected
  ${1} | ${1} | ${2}
  ${1} | ${2} | ${3}
  ${2} | ${1} | ${3}
`.test('returns $expected when adding $a to $b', ({ a, b, expected }) => {
  expect(a + b).toBe(expected);
});

.test.only(name, fn)

Aliases: .it.only(name, fn) or .fit(name, fn)

each`
  a    | b    | expected
  ${1} | ${1} | ${2}
  ${1} | ${2} | ${3}
  ${2} | ${1} | ${3}
`.test.only('returns $expected when adding $a to $b', ({ a, b, expected }) => {
  expect(a + b).toBe(expected);
});

.test.skip(name, fn)

Aliases: .it.skip(name, fn) or .xit(name, fn) or .xtest(name, fn)

each`
  a    | b    | expected
  ${1} | ${1} | ${2}
  ${1} | ${2} | ${3}
  ${2} | ${1} | ${3}
`.test.skip('returns $expected when adding $a to $b', ({ a, b, expected }) => {
  expect(a + b).toBe(expected);
});

Asynchronous .test(name, fn(done))

Alias: .it(name, fn(done))

each`
  str
  ${'hello'}
  ${'mr'}
  ${'spy'}
`.test('gives 007 secret message: $str', ({ str }, done) => {
  const asynchronousSpy = (message) => {
    expect(message).toBe(str);
    done();
  };
  callSomeAsynchronousFunction(asynchronousSpy)(str);
});

.describe(name, fn)

each`
  a    | b    | expected
  ${1} | ${1} | ${2}
  ${1} | ${2} | ${3}
  ${2} | ${1} | ${3}
`.describe('$a + $b', ({ a, b, expected }) => {
  test(`returns ${expected}`, () => {
    expect(a + b).toBe(expected);
  });

  test('does not mutate first arg', () => {
    a + b;
    expect(a).toBe(a);
  });

  test('does not mutate second arg', () => {
    a + b;
    expect(b).toBe(b);
  });
});

.describe.only(name, fn)

Aliases: .fdescribe(name, fn)

each`
  a    | b    | expected
  ${1} | ${1} | ${2}
  ${1} | ${2} | ${3}
  ${2} | ${1} | ${3}
`.describe.only('$a + $b', ({ a, b, expected }) => {
  test(`returns ${expected}`, () => {
    expect(a + b).toBe(expected);
  });
});

.describe.skip(name, fn)

Aliases: .xdescribe(name, fn)

each`
  a    | b    | expected
  ${1} | ${1} | ${2}
  ${1} | ${2} | ${3}
  ${2} | ${1} | ${3}
`.describe.skip('$a + $b', ({ a, b, expected }) => {
  test(`returns ${expected}`, () => {
    expect(a + b).toBe(expected);
  });
});

License

MIT