C harness for running TAP-compliant tests
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C TAP Harness 4.3

Build status

Copyright 2000-2001, 2004, 2006-2018 Russ Allbery eagle@eyrie.org. Copyright 2006-2009, 2011-2013 The Board of Trustees of the Leland Stanford Junior University. This software is distributed under a BSD-style license. Please see the section License below for more information.


C TAP Harness is a pure-C implementation of TAP, the Test Anything Protocol. TAP is the text-based protocol used by Perl's test suite. This package provides a harness similar to Perl's Test::Harness for running tests, with some additional features useful for test suites in packages that use Autoconf and Automake, and C and shell libraries to make writing TAP-compliant test programs easier.


This package started as the runtests program I wrote for INN in 2000 to serve as the basis for a new test suite using a test protocol similar to that used for Perl modules. When I started maintaining additional C packages, I adopted runtests for the test suite driver of those as well, resulting in further improvements but also separate copies of the same program in different distributions. The C TAP Harness distribution merges all the various versions into a single code base that all my packages can pull from.

C TAP Harness provides a full TAP specification driver (apart from a few possible edge cases) and has additional special features for supporting builds outside the source directory. It's mostly useful for packages using Autoconf and Automake and because it doesn't assume or require Perl.

The runtests program can be built with knowledge of the source and build directory and pass that knowledge on to test scripts, and will search for test scripts in both the source and build directory. This makes it easier for packages using Autoconf and Automake and supporting out-of-tree builds to build some test programs, ship others, and run them all regardless of what tree they're in. It also makes it easier for test cases to find their supporting files when they run.

Also included in this package are C and shell libraries that provide utility functions for writing test scripts that use TAP to report results. The C library also provides a variety of utility functions useful for test programs running as part of an Automake-built package: finding test data files, creating temporary files, reporting output from external programs running in the background, and similar common problems.


C TAP Harness requires a C compiler to build. Any ISO C89 or later C compiler on a system supporting the Single UNIX Specification, version 3 (SUSv3) should be sufficient. This should not be a problem on any modern system. The test suite and shell library require a Bourne-compatible shell. Outside of the test suite, C TAP Harness has no other prerequisites or requirements.

To bootstrap from a Git checkout, or if you change the Automake files and need to regenerate Makefile.in, you will need Automake 1.11 or later. For bootstrap or if you change configure.ac or any of the m4 files it includes and need to regenerate configure or config.h.in, you will need Autoconf 2.64 or later. Perl is also required to generate manual pages from a fresh Git checkout.


You can build C TAP Harness with the standard commands:


If you are building from a Git clone, first run ./bootstrap in the source directory to generate the build files. Building outside of the source directory is also supported, if you wish, by creating an empty directory and then running configure with the correct relative path.

Pass --enable-silent-rules to configure for a quieter build (similar to the Linux kernel). Use make warnings instead of make to build with full GCC compiler warnings (requires a relatively current version of GCC).

Installing C TAP Harness is not normally done. Instead, see the section on using the harness below.


C TAP Harness comes with a comprehensive test suite, which you can run after building with:

    make check

If a test fails, you can run a single test with verbose output via:

    tests/runtests -b $(pwd)/tests -s $(pwd)/tests -o <name-of-test>

Do this instead of running the test program directly since it will ensure that necessary environment variables are set up. You may need to change the -s option argument if you build with a separate build directory from the source directory.

To run the test suite, you will need Perl plus the Perl module Test::More, which comes with Perl 5.8 or later. The following additional Perl modules will be used by the test suite if present:

  • Test::Pod
  • Test::Spelling

All are available on CPAN. Those tests will be skipped if the modules are not available.

To enable tests that don't detect functionality problems but are used to sanity-check the release, set the environment variable RELEASE_TESTING to a true value. To enable tests that may be sensitive to the local environment or that produce a lot of false positives without uncovering many problems, set the environment variable AUTHOR_TESTING to a true value.

Using the Harness

While there is an install target that installs runtests in the default binary directory (/usr/local/bin by default) and installs the man pages, one normally wouldn't install anything from this package. Instead, the code is intended to be copied into your package and refreshed from the latest release of C TAP Harness for each release.

You can obviously copy the code and integrate it however works best for your package and your build system. Here's how I do it for my packages as an example:

  • Create a tests directory and copy tests/runtests.c into it. Create a tests/tap subdirectory and copy the portions of the TAP library (from tests/tap) that I need for that package into it. The TAP library is designed to let you drop in additional source and header files for additional utility functions that are useful in your package.

  • Add code to my top-level Makefile.am (I always use a non-recursive Makefile with subdir-objects set) to build runtests and the test library:

        check_PROGRAMS = tests/runtests
        tests_runtests_CPPFLAGS = -DC_TAP_SOURCE='"$(abs_top_srcdir)/tests"' \
        check_LIBRARIES = tests/tap/libtap.a
        tests_tap_libtap_a_CPPFLAGS = -I$(abs_top_srcdir)/tests
        tests_tap_libtap_a_SOURCES = tests/tap/basic.c tests/tap/basic.h \
                tests/tap/float.c tests/tap/float.h tests/tap/macros.h

    Omit float.c and float.h from the last line if your package doesn't need the is_double function. Building the build and source directories into runtests will let tests/runtests -o <test> work for users without requiring that they set any other variables, even if they're doing an out-of-source build.

    Add additional source files and headers that should go into the TAP library if you added extra utility functions for your package.

  • Add code to Makefile.am to run the test suite:

        check-local: $(check_PROGRAMS)
              cd tests && ./runtests -l $(abs_top_srcdir)/tests/TESTS

    See the Makefile.am in this package for an example.

  • List the test programs in the tests/TESTS file. This should have the name of the test executable with the trailing "-t" or ".t" (you can use either extension as you prefer) omitted.

    Test programs must be executable.

    For any test programs that need to be compiled, add build rules for them in Makefile.am, simliar to:

        tests_libtap_c_basic_LDADD = tests/tap/libtap.a

    and add them to check_PROGRAMS. If you include the float.c add-on in your libtap library, you will need to add -lm to the _LDADD setting for all test programs linked against it.

    A more complex example from the remctl package that needs additional libraries:

        tests_client_open_t_LDFLAGS = $(GSSAPI_LDFLAGS)
        tests_client_open_t_LDADD = client/libremctl.la tests/tap/libtap.a \
                util/libutil.la $(GSSAPI_LIBS)

    If the test program doesn't need to be compiled, add it to EXTRA_DIST so that it will be included in the distribution.

  • If you have test programs written in shell, copy tests/tap/libtap.sh the tap subdirectory of your tests directory and add it to EXTRA_DIST. Shell programs should start with:

        . "${C_TAP_SOURCE}/tap/libtap.sh"

    and can then use the functions defined in the library.

  • Optionally copy docs/writing-tests into your package somewhere, such as tests/README, as instructions to contributors on how to write tests for this framework.

If you have configuration files that the user must create to enable some of the tests, conventionally they go into tests/config.

If you have data files that your test cases use, conventionally they go into tests/data. You can then find the data directory relative to the C_TAP_SOURCE environment variable (set by runtests) in your test program. If you have data that's compiled or generated by Autoconf, it will be relative to the BUILD environment variable. Don't forget to add test data to EXTRA_DIST as necessary.

For more TAP library add-ons, generally ones that rely on additional portability code not shipped in this package or with narrower uses, see the rra-c-util package. There are several additional TAP library add-ons in the tests/tap directory in that package. It's also an example of how to use this test harness in another package.


The C TAP Harness web page will always have the current version of this package, the current documentation, and pointers to any additional resources.

For bug tracking, use the issue tracker on GitHub. However, please be aware that I tend to be extremely busy and work projects often take priority. I'll save your report and get to it as soon as I can, but it may take me a couple of months.

Source Repository

C TAP Harness is maintained using Git. You can access the current source on GitHub or by cloning the repository at:


or view the repository on the web.

The eyrie.org repository is the canonical one, maintained by the author, but using GitHub is probably more convenient for most purposes. Pull requests are gratefully reviewed and normally accepted.


The C TAP Harness package as a whole is covered by the following copyright statement and license:

Copyright 2000-2001, 2004, 2006-2018 Russ Allbery eagle@eyrie.org

Copyright 2006-2009, 2011-2013 The Board of Trustees of the Leland Stanford Junior University

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.


Some files in this distribution are individually released under different licenses, all of which are compatible with the above general package license but which may require preservation of additional notices. All required notices, and detailed information about the licensing of each file, are recorded in the LICENSE file.

Files covered by a license with an assigned SPDX License Identifier include SPDX-License-Identifier tags to enable automated processing of license information. See https://spdx.org/licenses/ for more information.

For any copyright range specified by files in this package as YYYY-ZZZZ, the range specifies every single year in that closed interval.