Each

The each directive provides a powerful way to generate multiple test cases from data tables or argument lists, enhancing your ability to run parameterized or data-driven tests.

List of Arguments

Run the same test for each value provided:

test.each(1, 2, 3)('...', (value) => {
    // ...
});

Tagged Template Table

Define input combinations with column headings:

describe.each` a | b | expected ${ 1 } | ${ 2 } | ${ 3 } ${ 2 } | ${ 3 } | ${ 5 }`
('%# adds $a and $b to get $expected', ({ a, b, expected }) => {
    test('calculates sum', () => {
        expect(a + b).toBe(expected);
    });
});

// OR

test.each`
    a       | b      | sum
    ${ 1 }  | ${ 2 } | ${ 3 }
    ${ 2 }  | ${ 5 } | ${ 7 }
`('adds $a + $b -> $sum', ({ a, b, sum }) => {
    expect(a + b).toBe(sum);
});

Test Name Formatting

Test names support advanced formatting:

Notation	Meaning	Example (Input)	Example (Result/Expr)
%p	Pretty-format output	'value: %p'	'value: [1,2,3]'
%s	String value	'value: %s'	'value: foo'
%d, %i	Number as integer	'id: %d'	'id: 42'
%f	Floating point value	'ratio: %f'	'ratio: 3.14'
%j	JSON string	'json: %j'	'json: {"a":1}'
%o	Object representation	'object: %o'	'object: {}'
%#	Index of the test case	'case %#'	'case 0'
%%	Single percent sign	'percent %% done'	'percent % done'
$variable	Inject property value (from arg object, e.g. $name)	'Hi, $name!'	'Hi, Jane!'
$variable.path	Inject nested property value ($user.info.id)	'$user.id'	'42'
$#	Index of the test case	'row $#'	'row 1'

**Note:**

• $variable, $variable.path, and $# interpolation works only with object-based test cases.
• $variable cannot be combined inside a % printf-format, except for %%.

each(test, 1, 2, 3)('test with %s', (val) => {
  expect(val).toBeGreaterThan(0);
});

test.each`name|age`(
  'John', 30,
  'Jane', 25
)('User %s is %s years old', (name, age) => {
  expect(typeof name).toBe('string');
  expect(typeof age).toBe('number');
});

test.each`
    a       | b      | sum
    ${ 1 }  | ${ 2 } | ${ 3 }
    ${ 2 }  | ${ 5 } | ${ 7 }
`('adds $a + $b -> $sum', ({ a, b, sum }) => {
    expect(a + b).toBe(sum);
});