You can get help on tap's command line interface by running tap -h.

Any configuration options may be set on the command line, in your package.json file in a tap section, or in a YAML-formatted .taprc file in the root of your project. See configuring tap for more information.

  tap [options] [<files>]

tap v16.3.1 - A Test-Anything-Protocol library for JavaScript

Executes all the files and interprets their output as TAP formatted test result
data. If no files are specified, then tap will search for testy-looking files,
and run those. (See '--test-regex' below.)

To parse TAP data from stdin, specify "-" as a filename.

Short options are parsed gnu-style, so for example '-bCRspec' would be
equivalent to '--bail --no-color --reporter=spec'

If the --check-coverage or --coverage-report options are provided explicitly,
and no test files are specified, then a coverage report or coverage check will
be run on the data from the last test run.

Coverage is never enabled for stdin.

Much more documentation available at:

Basic Options:

  -R<type> --reporter=<type>
                         Use the specified reporter. Defaults to 'base' when
                         colors are in use, or 'tap' when colors are disabled.

                         In addition to the built-in reporters provided by the
                         treport and tap-mocha-reporter modules, the reporter
                         option can also specify a command-line program or a
                         module to load via require().

                         Command-line programs receive the raw TAP output on
                         their stdin.

                         Modules loaded via require() must export either a
                         writable stream class or a React.Component subclass.
                         Writable streams are instantiated and piped into. React
                         components are rendered using Ink, with tap={tap} as
                         their only property.

                         Available built-in reporters: classic doc dot dump json
                         jsonstream landing list markdown min nyan progress
                         silent spec tap xunit base specy terse

  -r<arg> --reporter-arg=<arg>
                         Args to pass to command-line reporters. Ignored when
                         using built-in reporters or module reporters.
                         Can be set multiple times

  -F --save-fixture      Do not clean up fixtures created with t.testdir()
  --no-save-fixture      switch off the --save-fixture flag
  -b --bail              Bail out on first failure
  -B --no-bail           Do not bail out on first failure (default)
  --comments             Print all tap comments to process.stderr
  --no-comments          switch off the --comments flag
  -c --color             Use colors (Default for TTY)
  -C --no-color          Do not use colors (Default for non-TTY)

  -S --snapshot          Set to generate snapshot files for 't.matchSnapshot()'

  --no-snapshot          switch off the --snapshot flag

  -w --watch             Watch for changes in the test suite or covered program.

                         Runs the suite normally one time, and from then on,
                         re-run just the portions of the suite that are required
                         whenever a file changes.

                         Opens a REPL to trigger tests and perform various

  --no-watch             switch off the --watch flag

  -n --changed           Only run tests for files that have changed since the
                         last run.

                         This requires coverage to be enabled, because tap uses
                         NYC's process info tracking to monitor which file is
                         loaded by which tests.

                         If no prior test run data exists, then all default
                         files are run, as if --changed was not specified.

  --no-changed           switch off the --changed flag

  -s<file> --save=<file> If <file> exists, then it should be a line- delimited
                         list of test files to run. If <file> is not present,
                         then all command-line positional arguments are run.

                         After the set of test files are run, any failed test
                         files are written back to the save file.

                         This way, repeated runs with -s<file> will re-run
                         failures until all the failures are passing, and then
                         once again run all tests.

                         Its a good idea to .gitignore the file used for this
                         purpose, as it will churn a lot.

  -O --only              Only run tests with {only: true} option, or created
                         with t.only(...) function.

  --no-only              switch off the --only flag

  -g<pattern> --grep=<pattern>
                         Only run subtests tests matching the specified pattern.

                         Patterns are matched against top-level subtests in each
                         file. To filter tests at subsequent levels, specify
                         this option multiple times.

                         To specify regular expression flags, format pattern
                         like a JavaScript RegExp literal. For example: '/xyz/i'
                         for case-insensitive matching.

                         Can be set multiple times

  -i --invert            Invert the matches to --grep patterns. (Like grep -v)
  -I --no-invert         switch off the --invert flag

  -t<n> --timeout=<n>    Time out test files after <n> seconds. Defaults to 30,
                         or the value of the TAP_TIMEOUT environment variable.
                         Setting to 0 allows tests to run forever.

                         When a test process calls t.setTimeout(n) on the
                         top-level tap object, it also updates this value for
                         that specific process.

  -T --no-timeout        Do not time out tests. Equivalent to --timeout=0.

  --files=<files>        Alternative way to specify test set rather than using
                         positional arguments. Supported as an option so that
                         test file arguments can be specified in .taprc and
                         package.json files.
                         Can be set multiple times

Running Parallel Tests:

  Tap can run multiple test files in parallel. This generally results in a
  speedier test run, but can also cause problems if your test files are not
  designed to be independent from one another.

  To designate a set of files as ok to run in parallel, add them to a folder
  containing a file named 'tap-parallel-ok'.

  To designate a set of files as not ok to run in parallel, add them to a folder
  containing a file named 'tap-parallel-not-ok'.

  These folders may be nested within one another, and tap will do the right

  -j<n> --jobs=<n>       Run up to <n> test files in parallel.

                         By default, this will be set to the number of CPUs on
                         the system.

                         Set --jobs=1 to disable parallelization entirely.

  -J --jobs-auto         Run test files in parallel (auto calculated)

                         This is the default as of v13, so this option serves
                         little purpose except to re-set the parallelization
                         back to the default if an earlier option (or config
                         file) set it differently.

  --before=<module>      A node program to be run before test files are

                         Exiting with a non-zero status code or a signal will
                         fail the test run and exit the process in error.

  --after=<module>       A node program to be executed after tests are finished.

                         This will be run even if a test in the series fails
                         with a bailout, but it will *not* be run if a --before
                         script fails.

                         Exiting with a non-zero status code or a signal will
                         fail the test run and exit the process in error.

Code Coverage Options:

  Tap uses the nyc module internally to provide code coverage, so there is no
  need to invoke nyc yourself or depend on it directly unless you want to use it
  in other scenarios.

  --100                  Enforce full coverage, 100%. Sets branches, statements,
                         functions, and lines to 100.

                         This is the default. To specify a lower limit (or no
                         limit) set --lines, --branches, --functions, or
                         --statements to a lower number than 100, or disable
                         coverage checking with --no-check-coverage, or disable
                         coverage entirely with --no-coverage.

  -M<module> --coverage-map=<module>
                         Provide a path to a node module that exports a single
                         function. That function takes a test file as an
                         argument, and returns an array of files to instrument
                         with coverage when that file is run.

                         This is useful in cases where a unit test should cover
                         a single portion of the system under test.

                         Return 'null' to not cover any files by this test.

                         Return an empty array [] to cover the set that nyc
                         would pull in by default. Ie, returning [] is
                         equivalent to not using a coverage map at all.

  --no-coverage-map      Do not use a coverage map. Primarily useful for
                         disabling a coverage-map that is set in a config file.

  -cov --coverage        Capture coverage information using 'nyc' This is
                         enabled by default.

                         If a COVERALLS_REPO_TOKEN environment variable is set,
                         and the 'coveralls' module is installed, then coverage
                         is sent to the service.

                         Note that tap does not automatically install coveralls,
                         it must already be present in your project to use this

  -no-cov --no-coverage  Do not capture coverage information. Note that if nyc
                         is already loaded, then the coverage info will still be

                         Output coverage information using the specified
                         istanbul/nyc reporter type.

                         Default is 'text' when running on the command line, or
                         'text-lcov' when piping to coveralls.

                         If 'html' is used, then the report will be opened in a
                         web browser after running.

                         This can be run on its own at any time after a test run
                         that included coverage.

                         Built-in NYC reporters: clover cobertura html json
                         json-summary lcov lcovonly none teamcity text text-lcov

                         Can be set multiple times

  --no-coverage-report   Do not output a coverage report, even if coverage
                         information is generated.

  --browser              Open a browser when an html coverage report is
                         generated. (this is the default behavior)

  --no-browser           Do not open a web browser after generating an html
                         coverage report

  -pstree --show-process-tree
                         Enable coverage and display the tree of spawned

  --no-show-process-tree switch off the --show-process-tree flag

Coverage Enfocement Options:

  These options enable you to specify that the test will fail if a given
  coverage level is not met. Setting any of the options below will trigger the
  --coverage and --check-coverage flags.

  The most stringent is --100. You can find a list of projects running their
  tests like this at:

  If you run tests in this way, please add your project to the list.

  --check-coverage       Check whether coverage is within thresholds provided.
                         Setting this explicitly will default --coverage to

                         This can be run on its own any time after a test run
                         that included coverage.

  --no-check-coverage    switch off the --check-coverage flag
  --branches=<n>         what % of branches must be covered?
  --functions=<n>        what % of functions must be covered?
  --lines=<n>            what % of lines must be covered?
  --statements=<n>       what % of statements must be covered?

Other Options:

  -h --help              Show this helpful output
  --no-help              switch off the --help flag
  -v --version           Show the version of this program.
  --no-version           switch off the --version flag

  --test-regex=<pattern> A regular expression pattern indicating tests to run if
                         no positional arguments are provided.

                         By default, tap will search for all files ending in
                         .ts, .tsx, .js, .jsx, .cjs, or .mjs, in a top-level
                         folder named test, tests, or __tests__, or any file
                         ending in '.spec.' or '.test.' before a supported
                         extension, or a top-level file named
                         'test.(js,jsx,...)' or 'tests.(js,jsx,...)'

                         Ie, the default value for this option is:

                         Note that .jsx files will only be run when --jsx is
                         enabled, .ts files will only be run when --ts is
                         enabled, and .tsx files will only be run with both --ts
                         and --jsx are enabled.

                         When no positional arguments are provided, use the
                         supplied regular expression pattern to exclude tests
                         that would otherwise be matched by the test-regexp.

                         Defaults to '$.', which intentionally matches nothing.

                         Note: folders named tap-snapshots, node_modules, .git,
                         and .hg are ALWAYS excluded from the default test file
                         set. If you wish to run tests in these folders, then
                         name the test files on the command line as positional

  --test-arg=<arg>       Pass an argument to test files spawned by the tap
                         command line executable. This can be specified multiple
                         times to pass multiple args to test scripts.
                         Can be set multiple times

                         Pass a key=value (ie, --test-env=key=value) to set an
                         environment variable in the process where tests are

                         If a value is not provided, then the key is ensured to
                         not be set in the environment. To set a key to the
                         empty string, use --test-env=key=

                         Can be set multiple times

  --nyc-arg=<arg>        Pass an argument to nyc when running child processes
                         with coverage enabled. This can be specified multiple
                         times to pass multiple args to nyc.
                         Can be set multiple times

  --node-arg=<arg>       Pass an argument to Node binary in all child processes.
                         Run 'node --help' to see a list of all relevant
                         arguments. This can be specified multiple times to pass
                         multiple args to Node.
                         Can be set multiple times

  -gc --expose-gc        Expose the gc() function to Node.js tests
  --debug                Turn on debug mode
  --no-debug             switch off the --debug flag
  --debug-brk            Run JavaScript tests with node --debug-brk
  --harmony              Enable all Harmony flags in JavaScript tests
  --strict               Run JS tests in 'use strict' mode
  --flow                 Removes flow types
  --no-flow              switch off the --flow flag

  --ts                   Automatically load .ts and .tsx tests ts-node module.
                         Note: you must provide ts-node as a dependency
                         yourself, tap does not automatically bundle it.
                         (Default: false)

  --no-ts                switch off the --ts flag

  --jsx                  Automatically load .jsx tests using tap's bundled
                         import-jsx loader (Default: false)

  --no-jsx               switch off the --jsx flag

  --nyc-help             Print nyc usage banner. Useful for viewing options for

  --no-nyc-help          switch off the --nyc-help flag
  --nyc-version          Print version of nyc used by tap.
  --no-nyc-version       switch off the --nyc-version flag
  --parser-version       Print the version of tap-parser used by tap.
  --no-parser-version    switch off the --parser-version flag
  --versions             Print versions of tap, nyc, and tap-parser
  --no-versions          switch off the --versions flag
  --dump-config          Dump the config options in YAML format
  --no-dump-config       switch off the --dump-config flag

  --rcfile=<file>        Load any of these configurations from a YAML-formatted
                         file at the path specified. Defaults to .taprc in the
                         current working directory.

                         Run 'tap --dump-config' to see available options and

                         A module which exports an object of fields to assign
                         onto 'libtap/settings'. These are advanced
                         configuration options for modifying the behavior of
                         tap's internal runtime.

                         Module path is resolved relative to the current working

                         Allowed fields: rmdirRecursive, rmdirRecursiveSync,
                         StackUtils, stackUtils, output, snapshotFile.

                         See libtap documentation for expected values and usage.


  -o<file> --output-file=<file>
                         Send the raw TAP output to the specified file. Reporter
                         output will still be printed to stdout, but the file
                         will contain the raw TAP for later replay or analysis.

  -d<dir> --output-dir=<dir>
                         Send the raw TAP output to the specified directory. A
                         separate .tap file will be created for each test file
                         that is run. Reporter output will still be printed to
                         stdout, but the files will contain the raw TAP for
                         later replay or analysis.

                         Files will be created to match the folder structure and
                         filenames of test files run, but with '.tap' appended
                         to the filenames.

  --                     Stop parsing flags, and treat any additional command
                         line arguments as filenames.

Environment Variables:

  COVERALLS_REPO_TOKEN   Set to a Coveralls token to automatically send coverage
                         information to, if the 'coveralls'
                         module is installed in the project.

  TAP_CHILD_ID           Test files have this value set to a numeric value when
                         run through the test runner. It also appears on the
                         root tap object as `tap.childId`.

  TAP_SNAPSHOT           Set to '1' to generate snapshot files for
                         't.matchSnapshot()' assertions.

  TAP_RCFILE             A yaml formatted file which can set any of the above
                         options. Defaults to ./.taprc

  TAP_LIBTAP_SETTINGS    A path (relative to current working directory) of a
                         file that exports fields to override the default libtap

  TAP_TIMEOUT            Default value for --timeout option.

  TAP_COLORS             Set to '1' to force color output, or '0' to prevent
                         color output.

  TAP_BAIL               Bail out on the first test failure. Used internally
                         when '--bailout' is set.

  TAP                    Set to '1' to force standard TAP output, and suppress
                         any reporters. Used when running child tests so that
                         their output is parseable by the test harness.

  TAP_DIAG               Set to '1' to show diagnostics by default for passing
                         tests. Set to '0' to NOT show diagnostics by default
                         for failing tests. If not one of these two values, then
                         diagnostics are printed by default for failing tests,
                         and not for passing tests.

  TAP_BUFFER             Set to '1' to run subtests in buffered mode by default.

  TAP_DEV_LONGSTACK      Set to '1' to include node-tap internals in stack
                         traces. By default, these are included only when the
                         current working directory is the tap project itself.
                         Note that node internals are always excluded.

  TAP_DEBUG              Set to '1' to turn on debug mode.
  NODE_DEBUG             Include 'tap' to turn on debug mode.

  TAP_GREP               A '\n'-delimited list of grep patterns to apply to root
                         level test objects. (This is an implementation detail
                         for how the '--grep' option works.)

  TAP_GREP_INVERT        Set to '1' to invert the meaning of the patterns in
                         TAP_GREP. (Implementation detail for how the '--invert'
                         flag works.)

  TAP_ONLY               Set to '1' to set the --only flag
  TAP_TS                 Set to '1' to enable automatic typescript support
  TAP_JSX                Set to '1' to enable automatic jsx support

Config Files:

  You can create a yaml file with any of the options above. By default, the file
  at ./.taprc will be loaded, but the --rcfile option or TAP_RCFILE environment
  variable can modify this.

  Run 'tap --dump-config' for a listing of what can be set in that file. Each of
  the keys corresponds to one of the options above.