jest-each
Jest Parameterised Testing
[](https://www.npmjs.com/package/jest-each) [](http://npm-stat.com/charts.html?package=jest-each&from=2017-03-21) [](https://github.com/facebook/jest/blob/main/LICENSE)
A parameterised testing library for [Jest](https://jestjs.io/) inspired by [mocha-each](https://github.com/ryym/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`
- `.test.concurrent`
- Also under the alias: `.it.concurrent`
- `.test.concurrent.only`
- Also under the alias: `.it.concurrent.only`
- `.test.concurrent.skip`
- Also under the alias: `.it.concurrent.skip`
- `.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 [`printf` formatting](https://nodejs.org/api/util.html#util_util_format_format_args):
- `%p` - [pretty-format](https://www.npmjs.com/package/pretty-format).
- `%s`- String.
- `%d`- Number.
- `%i` - Integer.
- `%f` - Floating point value.
- `%j` - JSON.
- `%o` - Object.
- `%#` - Index of the test case.
- `%%` - single percent sign ('%'). This does not consume an argument.
- Unique test titles by injecting properties of test case object
- 🖖 Spock like data tables with [Tagged Template Literals](#tagged-template-literal-of-rows)
---
- [Demo](#demo)
- [Installation](#installation)
- [Importing](#importing)
- APIs
- [Array of Rows](#array-of-rows)
- [Usage](#usage)
- [Tagged Template Literal of rows](#tagged-template-literal-of-rows)
- [Usage](#usage-1)
## Demo
#### Tests without jest-each
#### Tests can be re-written with jest-each to:
**`.test`**
**`.test` with Tagged Template Literals**
**`.describe`**
## 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.
```js
// es6
import each from 'jest-each';
```
```js
// es5
const each = require('jest-each').default;
```
## 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
- _Note_ If you pass in a 1D array of primitives, internally it will be mapped to a table i.e. `[1, 2, 3] -> [[1], [2], [3]]`
##### `.test`:
- name: `String` the title of the `test`.
- Generate unique test titles by positionally injecting parameters with [`printf` formatting](https://nodejs.org/api/util.html#util_util_format_format_args):
- `%p` - [pretty-format](https://www.npmjs.com/package/pretty-format).
- `%s`- String.
- `%d`- Number.
- `%i` - Integer.
- `%f` - Floating point value.
- `%j` - JSON.
- `%o` - Object.
- `%#` - Index of the test case.
- `%%` - single percent sign ('%'). This does not consume an argument.
- Or generate unique test titles by injecting properties of test case object with `$variable`
- To inject nested object values use you can supply a keyPath i.e. `$variable.path.to.value`
- You can use `$#` to inject the index of the test case
- You cannot use `$variable` with the `printf` formatting except for `%%`
- 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
- _Note_ If you pass in a 1D array of primitives, internally it will be mapped to a table i.e. `[1, 2, 3] -> [[1], [2], [3]]`
##### `.describe`:
- name: `String` the title of the `describe`
- Generate unique test titles by positionally injecting parameters with [`printf` formatting](https://nodejs.org/api/util.html#util_util_format_format_args):
- `%p` - [pretty-format](https://www.npmjs.com/package/pretty-format).
- `%s`- String.
- `%d`- Number.
- `%i` - Integer.
- `%f` - Floating point value.
- `%j` - JSON.
- `%o` - Object.
- `%#` - Index of the test case.
- `%%` - single percent sign ('%'). This does not consume an argument.
- Or generate unique test titles by injecting properties of test case object with `$variable`
- To inject nested object values use you can supply a keyPath i.e. `$variable.path.to.value`
- You can use `$#` to inject the index of the test case
- You cannot use `$variable` with the `printf` formatting except for `%%`
- suiteFn: `Function` the suite of `test`/`it`s 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)`
```js
each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
]).test('returns the result of adding %d to %d', (a, b, expected) => {
expect(a + b).toBe(expected);
});
```
```js
each([
{a: 1, b: 1, expected: 2},
{a: 1, b: 2, expected: 3},
{a: 2, b: 1, expected: 3},
]).test('returns the result of 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)`
```js
each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
]).test.only('returns the result of adding %d to %d', (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)`
```js
each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
]).test.skip('returns the result of adding %d to %d', (a, b, expected) => {
expect(a + b).toBe(expected);
});
```
#### `.test.concurrent(name, fn)`
Aliases: `.it.concurrent(name, fn)`
```js
each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
]).test.concurrent(
'returns the result of adding %d to %d',
(a, b, expected) => {
expect(a + b).toBe(expected);
},
);
```
#### `.test.concurrent.only(name, fn)`
Aliases: `.it.concurrent.only(name, fn)`
```js
each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
]).test.concurrent.only(
'returns the result of adding %d to %d',
(a, b, expected) => {
expect(a + b).toBe(expected);
},
);
```
#### `.test.concurrent.skip(name, fn)`
Aliases: `.it.concurrent.skip(name, fn)`
```js
each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
]).test.concurrent.skip(
'returns the result of adding %d to %d',
(a, b, expected) => {
expect(a + b).toBe(expected);
},
);
```
#### Asynchronous `.test(name, fn(done))`
Alias: `.it(name, fn(done))`
```js
each([['hello'], ['mr'], ['spy']]).test(
'gives 007 secret message: %s',
(str, done) => {
const asynchronousSpy = message => {
expect(message).toBe(str);
done();
};
callSomeAsynchronousFunction(asynchronousSpy)(str);
},
);
```
#### `.describe(name, fn)`
```js
each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
]).describe('.add(%d, %d)', (a, b, expected) => {
test(`returns ${expected}`, () => {
expect(a + b).toBe(expected);
});
test('does not mutate first arg', () => {
a + b;
expect(a).toBe(a);
});
test('does not mutate second arg', () => {
a + b;
expect(b).toBe(b);
});
});
```
```js
each([
{a: 1, b: 1, expected: 2},
{a: 1, b: 2, expected: 3},
{a: 2, b: 1, expected: 3},
]).describe('.add($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)`
```js
each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
]).describe.only('.add(%d, %d)', (a, b, expected) => {
test(`returns ${expected}`, () => {
expect(a + b).toBe(expected);
});
});
```
#### `.describe.skip(name, fn)`
Aliases: `.xdescribe(name, fn)`
```js
each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
]).describe.skip('.add(%d, %d)', (a, b, expected) => {
test(`returns ${expected}`, () => {
expect(a + b).toBe(expected);
});
});
```
---
## Tagged Template Literal of rows
### API
#### `each[tagged template].test(name, suiteFn)`
```js
each`
a | b | expected
${1} | ${1} | ${2}
${1} | ${2} | ${3}
${2} | ${1} | ${3}
`.test('returns $expected when adding $a to $b', ({a, b, expected}) => {
expect(a + b).toBe(expected);
});
```
##### `each` takes a tagged template string with:
- First row of variable name column headings separated with `|`
- One or more subsequent rows of data supplied as template literal expressions using `${value}` syntax.
##### `.test`:
- name: `String` the title of the `test`, use `$variable` in the name string to inject test values into the test title from the tagged template expressions
- To inject nested object values use you can supply a keyPath i.e. `$variable.path.to.value`
- You can use `$#` to inject the index of the table row.
- 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)`
```js
each`
a | b | expected
${1} | ${1} | ${2}
${1} | ${2} | ${3}
${2} | ${1} | ${3}
`.describe('$a + $b', ({a, b, expected}) => {
test(`returns ${expected}`, () => {
expect(a + b).toBe(expected);
});
test('does not mutate first arg', () => {
a + b;
expect(a).toBe(a);
});
test('does not mutate second arg', () => {
a + b;
expect(b).toBe(b);
});
});
```
##### `each` takes a tagged template string with:
- First row of variable name column headings separated with `|`
- One or more subsequent rows of data supplied as template literal expressions using `${value}` syntax.
##### `.describe`:
- name: `String` the title of the `test`, use `$variable` in the name string to inject test values into the test title from the tagged template expressions
- To inject nested object values use you can supply a keyPath i.e. `$variable.path.to.value`
- suiteFn: `Function` the suite of `test`/`it`s 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)`
```js
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)`
```js
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)`
```js
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))`
```js
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)`
```js
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)`
```js
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)`
```js
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