Глобальные значения
В скриптах тестирования, Jest создает эти функции и объекты в г лобальной области видимости. Вам не нужно ничего импортировать или подключать к скрипту для работы с этими функциями и объектами. Однако, если вы предпочитаете импорт, вы можете импортировать {describe, expect, test} из '@jest/globals'
.
Примеры TypeScript с этой страницы будут работать только в том случае, если вы явно импортируете Jest API:
Import {expect, jest, test} from '@jest/globals';
Обратитесь к Началу работы за подробностями о том, как установить Jest с TypeScript.
Методы
- Справка
afterAll(fn, timeout)
afterEach(fn, timeout)
beforeAll(fn, timeout)
beforeEach(fn, timeout)
describe(name, fn)
describe.each(table)(name, fn, timeout)
describe.only(name, fn)
describe.only.each(table)(name, fn)
describe.skip(name, fn)
describe.skip.each(table)(name, fn)
test(name, fn, timeout)
test.concurrent(name, fn, timeout)
test.concurrent.each(table)(name, fn, timeout)
test.concurrent.only.each(table)(name, fn)
test.concurrent.skip.each(table)(name, fn)
test.each(table)(name, fn, timeout)
test.failing(name, fn, timeout)
test.failing.each(name, fn, timeout)
test.only.failing(name, fn, timeout)
test.skip.failing(name, fn, timeout)
test.only(name, fn, timeout)
test.only.each(table)(name, fn)
test.skip(name, fn)
test.skip.each(table)(name, fn)
test.todo(name)
- TypeScript Usage
Справка
afterAll(fn, timeout)
Выполняет функцию после всех тестов в этом файле. Если функция возвращает промис или является генератором, Jest ждет пока промис разрешится, а затем запускает тесты.
Optionally, you can provide a timeout
(in milliseconds) for specifying how long to wait for each row before aborting. The default timeout is 5 seconds.
Например:
Например:
const globalDatabase = makeGlobalDatabase();
function cleanUpDatabase(db) {
db.cleanUp();
}
afterAll(() => {
cleanUpDatabase(globalDatabase);
});
test('может найти запись', () => {
return globalDatabase.find('запись', {}, results => {
expect(results.length).toBeGreaterThan(0);
});
});
test('может добавить запись', () => {
return globalDatabase.insert('запись', makeThing(), response => {
expect(response.success).toBeTruthy();
});
});
Если afterAll
находится внутри блока describe
, то он запускается в конце блока describe.
Если вы хотите производить очистку после каждого теста, а не после всех тестов, то вместо этого используйте afterEach
.
Это может быть полезно, если вы хотите очистить некоторое временное состояние создаваемое каждым тестом.
afterEach(fn, timeout)
Выполняет функцию после каждого теста в файле. Если функция возвращает промис или является генератором, Jest ждет пока промис разрешится, а затем запускает тесты.
Optionally, you can provide a timeout
(in milliseconds) for specifying how long to wait for each row before aborting. The default timeout is 5 seconds.
Например:
Например:
const globalDatabase = makeGlobalDatabase();
function cleanUpDatabase(db) {
db.cleanUp();
}
afterEach(() => {
cleanUpDatabase(globalDatabase);
});
test('може найти запись', () => {
return globalDatabase.find('запись', {}, results => {
expect(results.length).toBeGreaterThan(0);
});
});
test('может добавить запись', () => {
return globalDatabase.insert('запись', makeThing(), response => {
expect(response.success).toBeTruthy();
});
});
Если afterEach
находится внутри блока describe
, то он запускается только после каждого теста внутри блока describe.
Если вы хотите провести очистку только один раз, после всех тестов, используйте afterAll
.
Если вы хотите провести очистку только один раз, после всех тестов, используйте afterAll
.
beforeAll(fn, timeout)
Выполняет функцию перед запуском каждого теста в этом файле. Если функция возвращает промис или является генератором, Jest ждет пока промис разрешится, а затем запускает тест.
Optionally, you can provide a timeout
(in milliseconds) for specifying how long to wait for each row before aborting. The default timeout is 5 seconds.
Например:
Например:
const globalDatabase = makeGlobalDatabase();
beforeEach(() => {
// Очищает базу данных и добавляет данные тестирования.
// Jest будет ждать завершения этого Promise перед запуском тестов.
return globalDatabase.clear().then(() => {
return globalDatabase.insert({testData: 'foo'});
});
});
test('can find things', () => {
return globalDatabase.find('thing', {}, results => {
expect(results.length).toBeGreaterThan(0);
});
});
test('can insert a thing', () => {
return globalDatabase.insert('thing', makeThing(), response => {
expect(response.success).toBeTruthy();
});
});
Здесь beforeAll
гарантирует, что база данных настроена, перед запуском тестов. If setup was synchronous, you could do this without beforeAll
. Ключевым является то, что Jest будет ждать разрешения промиса, поэтому вы можете установить асинхронно.
Если вместо запуска перед выполнением всех тестов, вы хотите что-то запускать перед каждым тестом, то используйте beforeEach
.
Если вместо запуска перед выполнением всех тестов, вы хотите что-то запускать перед каждым тестом, то используйте beforeEach
.
beforeEach(fn, timeout)
Выполняет функцию перед выполнением тестов в текущем файле. Если функция возвращает промис или является генератором, Jest ждет пока промис разрешится, а затем запускает тесты.
Optionally, you can provide a timeout
(in milliseconds) for specifying how long to wait for each row before aborting. The default timeout is 5 seconds.
This is often useful if you want to reset some global state that will be used by many tests.
Например:
const globalDatabase = makeGlobalDatabase();
beforeEach(() => {
// Clears the database and adds some testing data.
// Jest будет ждать завершения этого Promise перед запуском тестов.
return globalDatabase.clear().then(() => {
return globalDatabase.insert({testData: 'foo'});
});
});
// Since we only set up the database once in this example, it's important
// that our tests don't modify it. test('can find things', () => {
return globalDatabase.find('thing', {}, results => {
expect(results.length).toBeGreaterThan(0);
});
});
Here the beforeEach
ensures that the database is reset for each test.
If beforeEach
is inside a describe
block, it runs for each test in the describe block.
If you only need to run some setup code once, before any tests run, use beforeAll
instead.
describe(name, fn)
describe(name, fn)
группирует связанные по логике тесты в один блок. Например, если у вас есть объект myBeverage
, который должен быть вкусным (ключ "delicious"), но не кислым (ключ "sour"), вы можете протестировать его следующим образом:
const myBeverage = {
delicious: true,
sour: false,
};
describe('my beverage', () => {
test('is delicious', () => {
expect(myBeverage.delicious).toBeTruthy();
});
test('is not sour', () => {
expect(myBeverage.sour).toBeFalsy();
});
});
Это не обязательно, вы можете писать тесты в глобальном уровне. Но это может быть удобно, группировать некоторые тесты вместе.
You can also nest describe
blocks if you have a hierarchy of tests:
const binaryStringToNumber = binString => {
if (!/^[01]+$/.test(binString)) {
throw new CustomError('Not a binary number.');
}
return parseInt(binString, 2);
};
describe('binaryStringToNumber', () => {
describe('given an invalid binary string', () => {
test('composed of non-numbers throws CustomError', () => {
expect(() => binaryStringToNumber('abc')).toThrow(CustomError);
});
test('with extra whitespace throws CustomError', () => {
expect(() => binaryStringToNumber(' 100')).toThrow(CustomError);
});
});
describe('given a valid binary string', () => {
test('returns the correct number', () => {
expect(binaryStringToNumber('100')).toBe(4);
});
});
});
describe.each(table)(name, fn, timeout)
Используйте describe.each
если собираетесь дублировать одинаковые тесты с разными данными. describe.each
позволяет вам писать наборы тестов один раз и передавать в него данные.
describe.each
is available with two APIs:
1. describe.each(table)(name, fn, timeout)
-
table
:Массив
of Arrays with the arguments that are passed into thefn
for each row. 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]]
. -
наименование
:Строка
название теста.- Generate unique test titles by positionally injecting parameters with
printf
formatting:%p
- 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 theprintf
formatting except for%%
- To inject nested object values use you can supply a keyPath i.e.
- Generate unique test titles by positionally injecting parameters with
-
fn
:Function
the suite of tests to be run, this is the function that will receive the parameters in each row as function arguments. -
Optionally, you can provide a
timeout
(in milliseconds) for specifying how long to wait for each row before aborting. The default timeout is 5 seconds.
Пример:
describe.each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
])('.add(%i, %i)', (a, b, expected) => {
test(`returns ${expected}`, () => {
expect(a + b).toBe(expected);
});
test(`returned value not be greater than ${expected}`, () => {
expect(a + b).not.toBeGreaterThan(expected);
});
test(`returned value not be less than ${expected}`, () => {
expect(a + b).not.toBeLessThan(expected);
});
});
describe.each([
{a: 1, b: 1, expected: 2},
{a: 1, b: 2, expected: 3},
{a: 2, b: 1, expected: 3},
])('.add($a, $b)', ({a, b, expected}) => {
test(`returns ${expected}`, () => {
expect(a + b).toBe(expected);
});
test(`returned value not be greater than ${expected}`, () => {
expect(a + b).not.toBeGreaterThan(expected);
});
test(`returned value not be less than ${expected}`, () => {
expect(a + b).not.toBeLessThan(expected);
});
});
2. describe.each`table`(name, fn, timeout)
table
:Tagged Template Literal
- First row of variable name column headings separated with
|
- One or more subsequent rows of data supplied as template literal expressions using
${value}
syntax.
- First row of variable name column headings separated with
name
:String
the title of the test suite, use$variable
to inject test data into the suite title from the tagged template expressions, and$#
for the index of the row.- To inject nested object values use you can supply a keyPath i.e.
$variable.path.to.value
- To inject nested object values use you can supply a keyPath i.e.
fn
:Function
the suite of tests to be run, this is the function that will receive the test data object.- Optionally, you can provide a
timeout
(in milliseconds) for specifying how long to wait for each row before aborting. The default timeout is 5 seconds.
Пример:
describe.each`
a | b | expected
${1} | ${1} | ${2}
${1} | ${2} | ${3}
${2} | ${1} | ${3}
`('$a + $b', ({a, b, expected}) => {
test(`возвращает ${expected}`, () => {
expect(a + b).toBe(expected);
});
test(`возвращаемое значение не должно быть больше чем ${expected}`, () => {
expect(a + b).not.toBeGreaterThan(expected);
});
test(`возвращаемое значение не должно быть меньше чем ${expected}`, () => {
expect(a + b).not.toBeLessThan(expected);
});
});
describe.only(name, fn)
Also under the alias: fdescribe(name, fn)
You can use describe.only
if you want to run only one describe block:
describe.only('мой напиток', () => {
test('вкусный', () => {
expect(myBeverage.delicious).toBeTruthy();
});
test('не кислый', () => {
expect(myBeverage.sour).toBeFalsy();
});
});
describe('мои другие напитки', () => {
// будет пропущено
});
describe.only.each(table)(name, fn)
Also under the aliases: fdescribe.each(table)(name, fn)
and fdescribe.each`table`(name, fn)
Use describe.only.each
if you want to only run specific tests suites of data driven tests.
describe.only.each
is available with two APIs:
describe.only.each(table)(name, fn)
describe.only.each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
])('.add(%i, %i)', (a, b, expected) => {
test(`returns ${expected}`, () => {
expect(a + b).toBe(expected);
});
});
test('will not be run', () => {
expect(1 / 0).toBe(Infinity);
});
describe.only.each`table`(name, fn)
describe.only.each`
a | b | expected
${1} | ${1} | ${2}
${1} | ${2} | ${3}
${2} | ${1} | ${3}
`('returns $expected when $a is added to $b', ({a, b, expected}) => {
test('passes', () => {
expect(a + b).toBe(expected);
});
});
test('will not be run', () => {
expect(1 / 0).toBe(Infinity);
});
describe.skip(name, fn)
Also under the alias: xdescribe(name, fn)
You can use describe.skip
if you do not want to run the tests of a particular describe
block:
describe('мой напиток', () => {
test('вкусный', () => {
expect(myBeverage.delicious).toBeTruthy();
});
test('не кислый', () => {
expect(myBeverage.sour).toBeFalsy();
});
});
describe.skip('мои другие напитки', () => {
// ... будет пропущено
});
Using describe.skip
is often a cleaner alternative to temporarily commenting out a chunk of tests. Beware that the describe
block will still run. If you have some setup that also should be skipped, do it in a beforeAll
or beforeEach
block.
describe.skip.each(table)(name, fn)
Also under the aliases: xdescribe.each(table)(name, fn)
and xdescribe.each`table`(name, fn)
Use describe.skip.each
if you want to stop running a suite of data driven tests.
describe.skip.each
is available with two APIs:
describe.skip.each(table)(name, fn)
describe.skip.each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
])('.add(%i, %i)', (a, b, expected) => {
test(`returns ${expected}`, () => {
expect(a + b).toBe(expected); // will not be run
});
});
test('will be run', () => {
expect(1 / 0).toBe(Infinity);
});
describe.skip.each`table`(name, fn)
describe.skip.each`
a | b | expected
${1} | ${1} | ${2}
${1} | ${2} | ${3}
${2} | ${1} | ${3}
`('returns $expected when $a is added to $b', ({a, b, expected}) => {
test('will not be run', () => {
expect(a + b).toBe(expected); // will not be run
});
});
test('will be run', () => {
expect(1 / 0).toBe(Infinity);
});
test(name, fn, timeout)
Also under the alias: it(name, fn, timeout)
All you need in a test file is the test
method which runs a test. For example, let's say there's a function inchesOfRain()
that should be zero. Your whole test could be:
test('дождя не было', () => {
expect(inchesOfRain()).toBe(0);
});
The first argument is the test name; the second argument is a function that contains the expectations to test. The third argument (optional) is timeout
(in milliseconds) for specifying how long to wait before aborting. The default timeout is 5 seconds.
If a promise is returned from test
, Jest will wait for the promise to resolve before letting the test complete. For example, let's say fetchBeverageList()
returns a promise that is supposed to resolve to a list that has lemon
in it. You can write:
test('содержит ли лимон', () => {
return fetchBeverageList().then(list => {
expect(list).toContain('lemon');
});
});
Even though the call to test
will return right away, the test doesn't complete until the promise resolves. For more details, see Testing Asynchronous Code page.
Jest will also wait if you provide an argument to the test function, usually called done
. This could be handy when you want to test callbacks.
test.concurrent(name, fn, timeout)
Also under the alias: it.concurrent(name, fn, timeout)
test.concurrent
is considered experimental - see here for details on missing features and other issues.
Use test.concurrent
if you want the test to run concurrently.
The first argument is the test name; the second argument is an asynchronous function that contains the expectations to test. The third argument (optional) is timeout
(in milliseconds) for specifying how long to wait before aborting. The default timeout is 5 seconds.
test.concurrent('addition of 2 numbers', async () => {
expect(5 + 3).toBe(8);
});
test.concurrent('subtraction 2 numbers', async () => {
expect(5 - 3).toBe(2);
});
Use the maxConcurrency
configuration option to prevent Jest from executing more than the specified amount of tests at the same time.
test.concurrent.each(table)(name, fn, timeout)
Also under the alias: it.concurrent.each(table)(name, fn, timeout)
Используйте test.concurrent.each
если собираетесь дублировать одинаковые тесты с разными данными. test.each
allows you to write the test once and pass data in, the tests are all run asynchronously.
test.concurrent.each
is available with two APIs:
1. test.concurrent.each(table)(name, fn, timeout)
table
:Массив
of Arrays with the arguments that are passed into the testfn
for each row. 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]]
наименование
:Строка
the title of the test block.- Generate unique test titles by positionally injecting parameters with
printf
formatting:%p
- 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.
- Generate unique test titles by positionally injecting parameters with
fn
:Function
the test to be run, this is the function that will receive the parameters in each row as function arguments, this will have to be an asynchronous function.- Optionally, you can provide a
timeout
(in milliseconds) for specifying how long to wait for each row before aborting. The default timeout is 5 seconds.
Пример:
test.concurrent.each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
])('.add(%i, %i)', async (a, b, expected) => {
expect(a + b).toBe(expected);
});
2. test.concurrent.each`table`(name, fn, timeout)
table
:Tagged Template Literal
- First row of variable name column headings separated with
|
- One or more subsequent rows of data supplied as template literal expressions using
${value}
syntax.
- First row of variable name column headings separated with
наименование
:Строка
the title of the test, use$variable
to inject test data 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
- To inject nested object values use you can supply a keyPath i.e.
fn
:Function
the test to be run, this is the function that will receive the test data object, this will have to be an asynchronous function.- Optionally, you can provide a
timeout
(in milliseconds) for specifying how long to wait for each row before aborting. The default timeout is 5 seconds.
Пример:
test.concurrent.each`
a | b | expected
${1} | ${1} | ${2}
${1} | ${2} | ${3}
${2} | ${1} | ${3}
`('returns $expected when $a is added to $b', async ({a, b, expected}) => {
expect(a + b).toBe(expected);
});
test.concurrent.only.each(table)(name, fn)
Also under the alias: it.concurrent.only.each(table)(name, fn)
Use test.concurrent.only.each
if you want to only run specific tests with different test data concurrently.
test.concurrent.only.each
is available with two APIs:
test.concurrent.only.each(table)(name, fn)
test.concurrent.only.each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
])('.add(%i, %i)', async (a, b, expected) => {
expect(a + b).toBe(expected);
});
test('will not be run', () => {
expect(1 / 0).toBe(Infinity);
});
test.only.each`table`(name, fn)
test.concurrent.only.each`
a | b | expected
${1} | ${1} | ${2}
${1} | ${2} | ${3}
${2} | ${1} | ${3}
`('returns $expected when $a is added to $b', async ({a, b, expected}) => {
expect(a + b).toBe(expected);
});
test('will not be run', () => {
expect(1 / 0).toBe(Infinity);
});
test.concurrent.skip.each(table)(name, fn)
Also under the alias: it.concurrent.skip.each(table)(name, fn)
Use test.concurrent.skip.each
if you want to stop running a collection of asynchronous data driven tests.
test.concurrent.skip.each
is available with two APIs:
test.concurrent.skip.each(table)(name, fn)
test.concurrent.skip.each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
])('.add(%i, %i)', async (a, b, expected) => {
expect(a + b).toBe(expected); // will not be run
});
test('will be run', () => {
expect(1 / 0).toBe(Infinity);
});
test.concurrent.skip.each`table`(name, fn)
test.concurrent.skip.each`
a | b | expected
${1} | ${1} | ${2}
${1} | ${2} | ${3}
${2} | ${1} | ${3}
`('returns $expected when $a is added to $b', async ({a, b, expected}) => {
expect(a + b).toBe(expected); // will not be run
});
test('will be run', () => {
expect(1 / 0).toBe(Infinity);
});
test.each(table)(name, fn, timeout)
Можно воспользоваться алиасами: it.each(table)(name, fn)
и it.each`table`(name, fn)
Используйте test.each
если собираетесь дублировать одинаковые тесты с разными данными. test.each
позволяет вам писать тест один раз и передавать в него данные.
test.each
is available with two APIs:
1. test.each(table)(name, fn, timeout)
table
:Массив
of Arrays with the arguments that are passed into the testfn
for each row. 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]]
наименование
:Строка
the title of the test block.- Generate unique test titles by positionally injecting parameters with
printf
formatting:%p
- 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
$variable
with theprintf
formatting except for%%
- To inject nested object values use you can supply a keyPath i.e.
- Generate unique test titles by positionally injecting parameters with
fn
:Function
the test to be run, this is the function that will receive the parameters in each row as function arguments.- Optionally, you can provide a
timeout
(in milliseconds) for specifying how long to wait for each row before aborting. The default timeout is 5 seconds.
Пример:
test.each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
])('.add(%i, %i)', (a, b, expected) => {
expect(a + b).toBe(expected);
});
test.each([
{a: 1, b: 1, expected: 2},
{a: 1, b: 2, expected: 3},
{a: 2, b: 1, expected: 3},
])('.add($a, $b)', ({a, b, expected}) => {
expect(a + b).toBe(expected);
});
2. test.each`table`(name, fn, timeout)
table
:Tagged Template Literal
- First row of variable name column headings separated with
|
- One or more subsequent rows of data supplied as template literal expressions using
${value}
syntax.
- First row of variable name column headings separated with
наименование
:Строка
the title of the test, use$variable
to inject test data 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
- To inject nested object values use you can supply a keyPath i.e.
fn
:Function
the test to be run, this is the function that will receive the test data object.- Optionally, you can provide a
timeout
(in milliseconds) for specifying how long to wait for each row before aborting. The default timeout is 5 seconds.
Пример:
test.each`
a | b | expected
${1} | ${1} | ${2}
${1} | ${2} | ${3}
${2} | ${1} | ${3}
`('returns $expected when $a is added to $b', ({a, b, expected}) => {
expect(a + b).toBe(expected);
});
test.failing(name, fn, timeout)
Also under the alias: it.failing(name, fn, timeout)
This is only available with the default jest-circus runner.
Use test.failing
when you are writing a test and expecting it to fail. These tests will behave the other way normal tests do. If failing
test will throw any errors then it will pass. If it does not throw it will fail.
You can use this type of test i.e. when writing code in a BDD way. In that case the tests will not show up as failing until they pass. Then you can just remove the failing
modifier to make them pass.
It can also be a nice way to contribute failing tests to a project, even if you don't know how to fix the bug.
Пример:
test.failing('it is not equal', () => {
expect(5).toBe(6); // this test will pass
});
test.failing('it is equal', () => {
expect(10).toBe(10); // this test will fail
});
test.failing.each(name, fn, timeout)
Also under the alias: it.failing.each(table)(name, fn)
and it.failing.each`table`(name, fn)
This is only available with the default jest-circus runner.
You can also run multiple tests at once by adding each
after failing
.
Пример:
test.failing.each([
{a: 1, b: 1, expected: 2},
{a: 1, b: 2, expected: 3},
{a: 2, b: 1, expected: 3},
])('.add($a, $b)', ({a, b, expected}) => {
expect(a + b).toBe(expected);
});
test.only.failing(name, fn, timeout)
Also under the aliases: it.only.failing(name, fn, timeout)
, fit.failing(name, fn, timeout)
This is only available with the default jest-circus runner.
Use test.only.failing
if you want to only run a specific failing test.
test.skip.failing(name, fn, timeout)
Also under the aliases: it.skip.failing(name, fn, timeout)
, xit.failing(name, fn, timeout)
, xtest.failing(name, fn, timeout)
This is only available with the default jest-circus runner.
Use test.skip.failing
if you want to skip running a specific failing test.
test.only(name, fn, timeout)
Also under the aliases: it.only(name, fn, timeout)
, and fit(name, fn, timeout)
When you are debugging a large test file, you will often only want to run a subset of tests. You can use .only
to specify which tests are the only ones you want to run in that test file.
Optionally, you can provide a timeout
(in milliseconds) for specifying how long to wait for each row before aborting. The default timeout is 5 seconds.
For example, let's say you had these tests:
test.only('it is raining', () => {
expect(inchesOfRain()).toBeGreaterThan(0);
});
test('it is not snowing', () => {
expect(inchesOfSnow()).toBe(0);
});
Only the "it is raining" test will run in that test file, since it is run with test.only
.
Usually you wouldn't check code using test.only
into source control - you would use it for debugging, and remove it once you have fixed the broken tests.
test.only.each(table)(name, fn)
Also under the aliases: it.only.each(table)(name, fn)
, fit.each(table)(name, fn)
, it.only.each`table`(name, fn)
and fit.each`table`(name, fn)
Use test.only.each
if you want to only run specific tests with different test data.
test.only.each
is available with two APIs:
test.only.each(table)(name, fn)
test.only.each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
])('.add(%i, %i)', (a, b, expected) => {
expect(a + b).toBe(expected);
});
test('will not be run', () => {
expect(1 / 0).toBe(Infinity);
});
test.only.each`table`(name, fn)
test.only.each`
a | b | expected
${1} | ${1} | ${2}
${1} | ${2} | ${3}
${2} | ${1} | ${3}
`('returns $expected when $a is added to $b', ({a, b, expected}) => {
expect(a + b).toBe(expected);
});
test('will not be run', () => {
expect(1 / 0).toBe(Infinity);
});
test.skip(name, fn)
Also under the aliases: it.skip(name, fn)
, xit(name, fn)
, and xtest(name, fn)
When you are maintaining a large codebase, you may sometimes find a test that is temporarily broken for some reason. If you want to skip running this test, but you don't want to delete this code, you can use test.skip
to specify some tests to skip.
For example, let's say you had these tests:
test('it is raining', () => {
expect(inchesOfRain()).toBeGreaterThan(0);
});
test.skip('it is not snowing', () => {
expect(inchesOfSnow()).toBe(0);
});
Only the "it is raining" test will run, since the other test is run with test.skip
.
You could comment the test out, but it's often a bit nicer to use test.skip
because it will maintain indentation and syntax highlighting.
test.skip.each(table)(name, fn)
Also under the aliases: it.skip.each(table)(name, fn)
, xit.each(table)(name, fn)
, xtest.each(table)(name, fn)
, it.skip.each`table`(name, fn)
, xit.each`table`(name, fn)
and xtest.each`table`(name, fn)
Use test.skip.each
if you want to stop running a collection of data driven tests.
test.skip.each
is available with two APIs:
test.skip.each(table)(name, fn)
test.skip.each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
])('.add(%i, %i)', (a, b, expected) => {
expect(a + b).toBe(expected); // will not be run
});
test('will be run', () => {
expect(1 / 0).toBe(Infinity);
});
test.skip.each`table`(name, fn)
test.skip.each`
a | b | expected
${1} | ${1} | ${2}
${1} | ${2} | ${3}
${2} | ${1} | ${3}
`('returns $expected when $a is added to $b', ({a, b, expected}) => {
expect(a + b).toBe(expected); // will not be run
});
test('will be run', () => {
expect(1 / 0).toBe(Infinity);
});
test.todo(name)
Also under the alias: it.todo(name)
Use test.todo
when you are planning on writing tests. These tests will be highlighted in the summary output at the end so you know how many tests you still need todo.
const add = (a, b) => a + b;
test.todo('add should be associative');
test.todo
will throw an error if you pass it a test callback function. Use test.skip
instead, if you already implemented the test, but do not want it to run.
TypeScript Usage
Примеры TypeScript с этой страницы будут работать только в том случае, если вы явно импортируете Jest API:
Import {expect, jest, test} from '@jest/globals';
Обратитесь к Началу работы за подробностями о том, как установить Jest с TypeScript.
.each
The .each
modifier offers few different ways to define a table of the test cases. Some of the APIs have caveats related with the type inference of the arguments which are passed to describe
or test
callback functions. Let's take a look at each of them.
For simplicity test.each
is picked for the examples, but the type inference is identical in all cases where .each
modifier can be used: describe.each
, test.concurrent.only.each
, test.skip.each
, etc.
Array of objects
The array of objects API is most verbose, but it makes the type inference a painless task. A table
can be inlined:
import {test} from '@jest/globals';
test.each([
{name: 'a', path: 'path/to/a', count: 1, write: true},
{name: 'b', path: 'path/to/b', count: 3},
])('inline table', ({name, path, count, write}) => {
// arguments are typed as expected, e.g. `write: boolean | undefined`
});
Or declared separately as a variable:
import {test} from '@jest/globals';
const table = [
{a: 1, b: 2, expected: 'three', extra: true},
{a: 3, b: 4, expected: 'seven', extra: false},
{a: 5, b: 6, expected: 'eleven'},
];
test.each(table)('table as a variable', ({a, b, expected, extra}) => {
// again everything is typed as expected, e.g. `extra: boolean | undefined`
});
Array of arrays
The array of arrays style will work smoothly with inlined tables:
import {test} from '@jest/globals';
test.each([
[1, 2, 'three', true],
[3, 4, 'seven', false],
[5, 6, 'eleven'],
])('inline table example', (a, b, expected, extra) => {
// arguments are typed as expected, e.g. `extra: boolean | undefined`
});
However, if a table is declared as a separate variable, it must be typed as an array of tuples for correct type inference (this is not needed only if all elements of a row are of the same type):
import {test} from '@jest/globals';
const table: Array<[number, number, string, boolean?]> = [
[1, 2, 'three', true],
[3, 4, 'seven', false],
[5, 6, 'eleven'],
];
test.each(table)('table as a variable example', (a, b, expected, extra) => {
// without the annotation types are incorrect, e.g. `a: number | string | boolean`
});
Template literal
If all values are of the same type, the template literal API will type the arguments correctly:
import {test} from '@jest/globals';
test.each`
a | b | expected
${1} | ${2} | ${3}
${3} | ${4} | ${7}
${5} | ${6} | ${11}
`('template literal example', ({a, b, expected}) => {
// all arguments are of type `number`
});
Otherwise it will require a generic type argument:
import {test} from '@jest/globals';
test.each<{a: number; b: number; expected: string; extra?: boolean}>`
a | b | expected | extra
${1} | ${2} | ${'three'} | ${true}
${3} | ${4} | ${'seven'} | ${false}
${5} | ${6} | ${'eleven'}
`('template literal example', ({a, b, expected, extra}) => {
// without the generic argument in this case types would default to `unknown`
});