Interface It

Creates a test closure

interface It {
    concurrent: It;
    each: Each;
    failing: It;
    only: It;
    skip: It;
    todo: (name: string) => void;
    (name: string, fn?: ProvidesCallback, timeout?: number): void;
}
  • It(name: string, fn?: ProvidesCallback, timeout?: number): void

  • Creates a test closure.

    Parameters

    • name: string

      The name of your test

    • Optionalfn: ProvidesCallback

      The function for your test

    • Optionaltimeout: number

      The timeout for an async function test

    Returns void

Properties

concurrent each failing only skip todo

Properties

concurrent

concurrent: It

Experimental and should be avoided.

each

each: Each

Use if you keep duplicating the same test with different data. .each allows you to write the test once and pass data in.

.each is available with two APIs:

1 test.each(table)(name, fn)

  • table: Array of Arrays with the arguments that are passed into the test fn for each row.
  • name: String the title of the test block.
  • fn: Function the test to be run, this is the function that will receive the parameters in each row as function arguments.

2 test.each table(name, fn)

  • table: Tagged Template Literal
  • name: String the title of the test, use $variable to inject test data into the test title from the tagged template expressions.
  • fn: Function the test to be run, this is the function that will receive the test data object.

Example

// API 1
test.each([[1, 1, 2], [1, 2, 3], [2, 1, 3]])(
  '.add(%i, %i)',
  (a, b, expected) => {
    expect(a + b).toBe(expected);
  },
);

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

failing

failing: It

Mark this test as expecting to fail.

Only available in the default jest-circus runner.

only

only: It

Only runs this test in the current file.

skip

skip: It

Skips running this test in the current file.

todo

todo: (name: string) => void

Sketch out which tests to write in the future.

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