Environment and CLI
===================

Tests built with Criterion expose by default various command line switchs
and environment variables to alter their runtime behaviour.

Command line arguments
----------------------

* ``-h or --help``: Show a help message with the available switches.
* ``-q or --quiet``: Disables all logging.
* ``-v or --version``: Prints the version of criterion that has been
  linked against.
* ``-l or --list``: Print all the tests in a list.
* ``-f or --fail-fast``: Exit after the first test failure.
* ``--ascii``: Don't use fancy unicode symbols or colors in the output.
* ``-jN or --jobs N``: Use ``N`` parallel jobs to run the tests. ``0`` picks
  a number of jobs ideal for your hardware configuration.
* ``--pattern [PATTERN]``: Run tests whose string identifier matches
  the given shell wildcard pattern (see dedicated section below). (\*nix only)
* ``--no-early-exit``: The test workers shall not prematurely exit when done and
  will properly return from the main, cleaning up their process space.
  This is useful when tracking memory leaks with ``valgrind --tool=memcheck``.
* ``-S or --short-filename``: The filenames are displayed in their short form.
* ``--always-succeed``: The process shall exit with a status of ``0``.
* ``--tap[=FILE]``: Writes a TAP (Test Anything Protocol) report to FILE.
  No file or ``"-"`` means ``stderr``. This option is equivalent to
  ``--output=tap:FILE``.
* ``--xml[=FILE]``: Writes JUnit4 XML report to FILE.
  No file or ``"-"`` means ``stderr``. This option is equivalent to
  ``--output=xml:FILE``.
* ``--verbose[=level]``: Makes the output verbose. When provided with an integer,
  sets the verbosity level to that integer.
* ``-OPROVIDER:FILE or --output=PROVIDER:FILE``: Write a test report to FILE
  using the output provider named by PROVIDER. FILE may be a relative path, or
  ``"-"`` to write to ``stderr``.

Shell Wildcard Pattern
----------------------

Extglob patterns in criterion are matched against a test's string identifier.
This feature is only available on \*nix systems where ``PCRE`` is provided.

In the table below, a ``pattern-list`` is a list of patterns separated by ``|``.
Any extglob pattern can be constructed by combining any of the following
sub-patterns:

==================== ======================================================
Pattern              Meaning
==================== ======================================================
``*``                matches everything
-------------------- ------------------------------------------------------
``?``                matches any character
-------------------- ------------------------------------------------------
``[seq]``            matches any character in *seq*
-------------------- ------------------------------------------------------
``[!seq]``           matches any character not in *seq*
-------------------- ------------------------------------------------------
``?(pattern-list)``  Matches zero or one occurrence of the given patterns
-------------------- ------------------------------------------------------
``*(pattern-list)``  Matches zero or more occurrences of the given patterns
-------------------- ------------------------------------------------------
``+(pattern-list)``  Matches one or more occurrences of the given patterns
-------------------- ------------------------------------------------------
``@(pattern-list)``  Matches one of the given patterns
-------------------- ------------------------------------------------------
``!(pattern-list)``  Matches anything except one of the given patterns
==================== ======================================================

A test string identifier is of the form ``suite-name/test-name``, so a pattern
of ``simple/*`` matches every tests in the ``simple`` suite, ``*/passing``
matches all tests named ``passing`` regardless of the suite, and ``*`` matches
every possible test.

Environment Variables
---------------------

Environment variables are alternatives to command line switches when set to 1.

* ``CRITERION_ALWAYS_SUCCEED``:  Same as ``--always-succeed``.
* ``CRITERION_NO_EARLY_EXIT``:   Same as ``--no-early-exit``.
* ``CRITERION_FAIL_FAST``:       Same as ``--fail-fast``.
* ``CRITERION_USE_ASCII``:       Same as ``--ascii``.
* ``CRITERION_JOBS``:            Same as ``jobs``. Sets the number of jobs to
  its value.
* ``CRITERION_SHORT_FILENAME``:  Same as ``--short-filename``.
* ``CRITERION_VERBOSITY_LEVEL``: Same as ``--verbose``. Sets the verbosity level
  to its value.
* ``CRITERION_TEST_PATTERN``:    Same as ``--pattern``. Sets the test pattern
  to its value. (\*nix only)