Test runner
Table des matières
- Subtests
- Skipping tests
- describe/it syntax
- Filtering tests by name
- Extraneous asynchronous activity
- Running tests from the command line
- run([options])
- test([name][, options][, fn])
- describe([name][, options][, fn])
- describe.skip([name][, options][, fn])
- describe.todo([name][, options][, fn])
- it([name][, options][, fn])
- it.skip([name][, options][, fn])
- it.todo([name][, options][, fn])
- before([fn][, options])
- after([fn][, options])
- beforeEach([fn][, options])
- afterEach([fn][, options])
- Class: TapStream
- Class: TestContext
- Class: SuiteContext
Ajouté en: v18.0.0
Code source: lib/test.js
The node:test
module facilitates the creation of JavaScript tests that
report results in TAP format. To access it:
MJS
CJS
This module is only available under the node:
scheme. The following will not
work:
MJS
CJS
Tests created via the test
module consist of a single function that is
processed in one of three ways:
- A synchronous function that is considered failing if it throws an exception, and is considered passing otherwise.
- A function that returns a
Promise
that is considered failing if thePromise
rejects, and is considered passing if thePromise
resolves. - A function that receives a callback function. If the callback receives any
truthy value as its first argument, the test is considered failing. If a
falsy value is passed as the first argument to the callback, the test is
considered passing. If the test function receives a callback function and
also returns a
Promise
, the test will fail.
The following example illustrates how tests are written using the
test
module.
JS
As a test file executes, TAP is written to the standard output of the Node.js
process. This output can be interpreted by any test harness that understands
the TAP format. If any tests fail, the process exit code is set to 1
.
Subtests
The test context's test()
method allows subtests to be created. This method
behaves identically to the top level test()
function. The following example
demonstrates the creation of a top level test with two subtests.
JS
In this example, await
is used to ensure that both subtests have completed.
This is necessary because parent tests do not wait for their subtests to
complete. Any subtests that are still outstanding when their parent finishes
are cancelled and treated as failures. Any subtest failures cause the parent
test to fail.
Skipping tests
Individual tests can be skipped by passing the skip
option to the test, or by
calling the test context's skip()
method. Both of these options support
including a message that is displayed in the TAP output as shown in the
following example.
JS
M describe
/it
syntax
Running tests can also be done using describe
to declare a suite
and it
to declare a test.
A suite is used to organize and group related tests together.
it
is an alias for test
, except there is no test context passed,
since nesting is done using suites.
JS
describe
and it
are imported from the node:test
module.
MJS
CJS
M only
tests
If Node.js is started with the --test-only
command-line option, it is
possible to skip all top level tests except for a selected subset by passing
the only
option to the tests that should be run. When a test with the only
option set is run, all subtests are also run. The test context's runOnly()
method can be used to implement the same behavior at the subtest level.
JS
Filtering tests by name
The --test-name-pattern
command-line option can be used to only run tests
whose name matches the provided pattern. Test name patterns are interpreted as
JavaScript regular expressions. The --test-name-pattern
option can be
specified multiple times in order to run nested tests. For each test that is
executed, any corresponding test hooks, such as beforeEach()
, are also
run.
Given the following test file, starting Node.js with the
--test-name-pattern="test [1-3]"
option would cause the test runner to execute
test 1
, test 2
, and test 3
. If test 1
did not match the test name
pattern, then its subtests would not execute, despite matching the pattern. The
same set of tests could also be executed by passing --test-name-pattern
multiple times (e.g. --test-name-pattern="test 1"
,
--test-name-pattern="test 2"
, etc.).
JS
Test name patterns can also be specified using regular expression literals. This
allows regular expression flags to be used. In the previous example, starting
Node.js with --test-name-pattern="/test [4-5]/i"
would match Test 4
and
Test 5
because the pattern is case-insensitive.
Test name patterns do not change the set of files that the test runner executes.
Extraneous asynchronous activity
Once a test function finishes executing, the TAP results are output as quickly as possible while maintaining the order of the tests. However, it is possible for the test function to generate asynchronous activity that outlives the test itself. The test runner handles this type of activity, but does not delay the reporting of test results in order to accommodate it.
In the following example, a test completes with two setImmediate()
operations still outstanding. The first setImmediate()
attempts to create a
new subtest. Because the parent test has already finished and output its
results, the new subtest is immediately marked as failed, and reported in the
top level of the file's TAP output.
The second setImmediate()
creates an uncaughtException
event.
uncaughtException
and unhandledRejection
events originating from a completed
test are handled by the test
module and reported as diagnostic warnings in
the top level of the file's TAP output.
JS
Running tests from the command line
The Node.js test runner can be invoked from the command line by passing the
--test
flag:
BASH
By default, Node.js will recursively search the current directory for JavaScript source files matching a specific naming convention. Matching files are executed as test files. More information on the expected test file naming convention and behavior can be found in the test runner execution model section.
Alternatively, one or more paths can be provided as the final argument(s) to the Node.js command, as shown below.
BASH
In this example, the test runner will execute the files test1.js
and
test2.mjs
. The test runner will also recursively search the
custom_test_dir/
directory for test files to execute.
Test runner execution model
When searching for test files to execute, the test runner behaves as follows:
- Any files explicitly provided by the user are executed.
- If the user did not explicitly specify any paths, the current working directory is recursively searched for files as specified in the following steps.
node_modules
directories are skipped unless explicitly provided by the user.- If a directory named
test
is encountered, the test runner will search it recursively for all all.js
,.cjs
, and.mjs
files. All of these files are treated as test files, and do not need to match the specific naming convention detailed below. This is to accommodate projects that place all of their tests in a singletest
directory. - In all other directories,
.js
,.cjs
, and.mjs
files matching the following patterns are treated as test files:^test$
- Files whose basename is the string'test'
. Examples:test.js
,test.cjs
,test.mjs
.^test-.+
- Files whose basename starts with the string'test-'
followed by one or more characters. Examples:test-example.js
,test-another-example.mjs
..+[\.\-\_]test$
- Files whose basename ends with.test
,-test
, or_test
, preceded by one or more characters. Examples:example.test.js
,example-test.cjs
,example_test.mjs
.- Other file types understood by Node.js such as
.node
and.json
are not automatically executed by the test runner, but are supported if explicitly provided on the command line.
Each matching test file is executed in a separate child process. If the child
process finishes with an exit code of 0, the test is considered passing.
Otherwise, the test is considered to be a failure. Test files must be
executable by Node.js, but are not required to use the node:test
module
internally.
M run([options])
Ajouté en: v18.9.0
options
Object
Configuration options for running tests. The following properties are supported:concurrency
number
|boolean
If a number is provided, then that many files would run in parallel. If truthy, it would run (number of cpu cores - 1) files in parallel. If falsy, it would only run one file at a time. If unspecified, subtests inherit this value from their parent. Default:true
.files
:Array
An array containing the list of files to run. Default matching files from test runner execution model.signal
AbortSignal
Allows aborting an in-progress test execution.timeout
number
A number of milliseconds the test execution will fail after. If unspecified, subtests inherit this value from their parent. Default:Infinity
.inspectPort
number
|Function
Sets inspector port of test child process. This can be a number, or a function that takes no arguments and returns a number. If a nullish value is provided, each process gets its own port, incremented from the primary'sprocess.debugPort
. Default:undefined
.
- Returns:
TapStream
JS
M test([name][, options][, fn])
Historique
Version | Changements |
---|---|
v18.8.0 | Add a `signal` option. |
v18.7.0 | Add a `timeout` option. |
v18.0.0 | Ajouté en: v18.0.0 |
name
string
The name of the test, which is displayed when reporting test results. Default: Thename
property offn
, or'<anonymous>'
iffn
does not have a name.options
Object
Configuration options for the test. The following properties are supported:concurrency
number
|boolean
If a number is provided, then that many tests would run in parallel. If truthy, it would run (number of cpu cores - 1) tests in parallel. For subtests, it will beInfinity
tests in parallel. If falsy, it would only run one test at a time. If unspecified, subtests inherit this value from their parent. Default:false
.only
boolean
If truthy, and the test context is configured to runonly
tests, then this test will be run. Otherwise, the test is skipped. Default:false
.signal
AbortSignal
Allows aborting an in-progress test.skip
boolean
|string
If truthy, the test is skipped. If a string is provided, that string is displayed in the test results as the reason for skipping the test. Default:false
.todo
boolean
|string
If truthy, the test marked asTODO
. If a string is provided, that string is displayed in the test results as the reason why the test isTODO
. Default:false
.timeout
number
A number of milliseconds the test will fail after. If unspecified, subtests inherit this value from their parent. Default:Infinity
.
fn
Function
|AsyncFunction
The function under test. The first argument to this function is aTestContext
object. If the test uses callbacks, the callback function is passed as the second argument. Default: A no-op function.- Returns:
Promise
Resolved withundefined
once the test completes.
The test()
function is the value imported from the test
module. Each
invocation of this function results in the creation of a test point in the TAP
output.
The TestContext
object passed to the fn
argument can be used to perform
actions related to the current test. Examples include skipping the test, adding
additional TAP diagnostic information, or creating subtests.
test()
returns a Promise
that resolves once the test completes. The return
value can usually be discarded for top level tests. However, the return value
from subtests should be used to prevent the parent test from finishing first
and cancelling the subtest as shown in the following example.
JS
The timeout
option can be used to fail the test if it takes longer than
timeout
milliseconds to complete. However, it is not a reliable mechanism for
canceling tests because a running test might block the application thread and
thus prevent the scheduled cancellation.
M describe([name][, options][, fn])
name
string
The name of the suite, which is displayed when reporting test results. Default: Thename
property offn
, or'<anonymous>'
iffn
does not have a name.options
Object
Configuration options for the suite. supports the same options astest([name][, options][, fn])
.fn
Function
|AsyncFunction
The function under suite declaring all subtests and subsuites. The first argument to this function is aSuiteContext
object. Default: A no-op function.- Returns:
undefined
.
The describe()
function imported from the node:test
module. Each
invocation of this function results in the creation of a Subtest
and a test point in the TAP output.
After invocation of top level describe
functions,
all top level tests and suites will execute.
M describe.skip([name][, options][, fn])
Shorthand for skipping a suite, same as describe([name], { skip: true }[, fn])
.
M describe.todo([name][, options][, fn])
Shorthand for marking a suite as TODO
, same as
describe([name], { todo: true }[, fn])
.
M it([name][, options][, fn])
name
string
The name of the test, which is displayed when reporting test results. Default: Thename
property offn
, or'<anonymous>'
iffn
does not have a name.options
Object
Configuration options for the suite. supports the same options astest([name][, options][, fn])
.fn
Function
|AsyncFunction
The function under test. If the test uses callbacks, the callback function is passed as an argument. Default: A no-op function.- Returns:
undefined
.
The it()
function is the value imported from the node:test
module.
Each invocation of this function results in the creation of a test point in the
TAP output.
M it.skip([name][, options][, fn])
Shorthand for skipping a test,
same as it([name], { skip: true }[, fn])
.
M it.todo([name][, options][, fn])
Shorthand for marking a test as TODO
,
same as it([name], { todo: true }[, fn])
.
M before([fn][, options])
Ajouté en: v18.8.0
fn
Function
|AsyncFunction
The hook function. If the hook uses callbacks, the callback function is passed as the second argument. Default: A no-op function.options
Object
Configuration options for the hook. The following properties are supported:signal
AbortSignal
Allows aborting an in-progress hook.timeout
number
A number of milliseconds the hook will fail after. If unspecified, subtests inherit this value from their parent. Default:Infinity
.
This function is used to create a hook running before running a suite.
JS
M after([fn][, options])
Ajouté en: v18.8.0
fn
Function
|AsyncFunction
The hook function. If the hook uses callbacks, the callback function is passed as the second argument. Default: A no-op function.options
Object
Configuration options for the hook. The following properties are supported:signal
AbortSignal
Allows aborting an in-progress hook.timeout
number
A number of milliseconds the hook will fail after. If unspecified, subtests inherit this value from their parent. Default:Infinity
.
This function is used to create a hook running after running a suite.
JS
M beforeEach([fn][, options])
Ajouté en: v18.8.0
fn
Function
|AsyncFunction
The hook function. If the hook uses callbacks, the callback function is passed as the second argument. Default: A no-op function.options
Object
Configuration options for the hook. The following properties are supported:signal
AbortSignal
Allows aborting an in-progress hook.timeout
number
A number of milliseconds the hook will fail after. If unspecified, subtests inherit this value from their parent. Default:Infinity
.
This function is used to create a hook running before each subtest of the current suite.
JS
M afterEach([fn][, options])
Ajouté en: v18.8.0
fn
Function
|AsyncFunction
The hook function. If the hook uses callbacks, the callback function is passed as the second argument. Default: A no-op function.options
Object
Configuration options for the hook. The following properties are supported:signal
AbortSignal
Allows aborting an in-progress hook.timeout
number
A number of milliseconds the hook will fail after. If unspecified, subtests inherit this value from their parent. Default:Infinity
.
This function is used to create a hook running after each subtest of the current test.
JS
C TapStream
Ajouté en: v18.9.0
- Extends
ReadableStream
A successful call to run()
method will return a new TapStream
object, streaming a TAP output
TapStream
will emit events, in the order of the tests definition
E 'test:diagnostic'
message
string
The diagnostic message.
Emitted when context.diagnostic
is called.
E 'test:fail'
data
Object
duration
number
The test duration.error
Error
The failure casing test to fail.name
string
The test name.testNumber
number
The ordinal number of the test.todo
string
|undefined
Present ifcontext.todo
is calledskip
string
|undefined
Present ifcontext.skip
is called
Emitted when a test fails.
E 'test:pass'
data
Object
duration
number
The test duration.name
string
The test name.testNumber
number
The ordinal number of the test.todo
string
|undefined
Present ifcontext.todo
is calledskip
string
|undefined
Present ifcontext.skip
is called
Emitted when a test passes.
C TestContext
Ajouté en: v18.0.0
An instance of TestContext
is passed to each test function in order to
interact with the test runner. However, the TestContext
constructor is not
exposed as part of the API.
M context.beforeEach([fn][, options])
Ajouté en: v18.8.0
fn
Function
|AsyncFunction
The hook function. The first argument to this function is aTestContext
object. If the hook uses callbacks, the callback function is passed as the second argument. Default: A no-op function.options
Object
Configuration options for the hook. The following properties are supported:signal
AbortSignal
Allows aborting an in-progress hook.timeout
number
A number of milliseconds the hook will fail after. If unspecified, subtests inherit this value from their parent. Default:Infinity
.
This function is used to create a hook running before each subtest of the current test.
JS
M context.afterEach([fn][, options])
Ajouté en: v18.8.0
fn
Function
|AsyncFunction
The hook function. The first argument to this function is aTestContext
object. If the hook uses callbacks, the callback function is passed as the second argument. Default: A no-op function.options
Object
Configuration options for the hook. The following properties are supported:signal
AbortSignal
Allows aborting an in-progress hook.timeout
number
A number of milliseconds the hook will fail after. If unspecified, subtests inherit this value from their parent. Default:Infinity
.
This function is used to create a hook running after each subtest of the current test.
JS
M context.diagnostic(message)
Ajouté en: v18.0.0
message
string
Message to be displayed as a TAP diagnostic.
This function is used to write TAP diagnostics to the output. Any diagnostic information is included at the end of the test's results. This function does not return a value.
JS
M context.name
Ajouté en: v18.8.0
The name of the test.
M context.runOnly(shouldRunOnlyTests)
Ajouté en: v18.0.0
shouldRunOnlyTests
boolean
Whether or not to runonly
tests.
If shouldRunOnlyTests
is truthy, the test context will only run tests that
have the only
option set. Otherwise, all tests are run. If Node.js was not
started with the --test-only
command-line option, this function is a
no-op.
JS
M context.signal
Ajouté en: v18.7.0
AbortSignal
Can be used to abort test subtasks when the test has been aborted.
JS
M context.skip([message])
Ajouté en: v18.0.0
message
string
Optional skip message to be displayed in TAP output.
This function causes the test's output to indicate the test as skipped. If
message
is provided, it is included in the TAP output. Calling skip()
does
not terminate execution of the test function. This function does not return a
value.
JS
M context.todo([message])
Ajouté en: v18.0.0
message
string
OptionalTODO
message to be displayed in TAP output.
This function adds a TODO
directive to the test's output. If message
is
provided, it is included in the TAP output. Calling todo()
does not terminate
execution of the test function. This function does not return a value.
JS
M context.test([name][, options][, fn])
Historique
Version | Changements |
---|---|
v18.8.0 | Add a `signal` option. |
v18.7.0 | Add a `timeout` option. |
v18.0.0 | Ajouté en: v18.0.0 |
name
string
The name of the subtest, which is displayed when reporting test results. Default: Thename
property offn
, or'<anonymous>'
iffn
does not have a name.options
Object
Configuration options for the subtest. The following properties are supported:concurrency
number
The number of tests that can be run at the same time. If unspecified, subtests inherit this value from their parent. Default:1
.only
boolean
If truthy, and the test context is configured to runonly
tests, then this test will be run. Otherwise, the test is skipped. Default:false
.signal
AbortSignal
Allows aborting an in-progress test.skip
boolean
|string
If truthy, the test is skipped. If a string is provided, that string is displayed in the test results as the reason for skipping the test. Default:false
.todo
boolean
|string
If truthy, the test marked asTODO
. If a string is provided, that string is displayed in the test results as the reason why the test isTODO
. Default:false
.timeout
number
A number of milliseconds the test will fail after. If unspecified, subtests inherit this value from their parent. Default:Infinity
.
fn
Function
|AsyncFunction
The function under test. The first argument to this function is aTestContext
object. If the test uses callbacks, the callback function is passed as the second argument. Default: A no-op function.- Returns:
Promise
Resolved withundefined
once the test completes.
This function is used to create subtests under the current test. This function
behaves in the same fashion as the top level test()
function.
JS
C SuiteContext
Ajouté en: v18.7.0
An instance of SuiteContext
is passed to each suite function in order to
interact with the test runner. However, the SuiteContext
constructor is not
exposed as part of the API.
M context.name
Ajouté en: v18.8.0
The name of the suite.
M context.signal
Ajouté en: v18.7.0
AbortSignal
Can be used to abort test subtasks when the test has been aborted.