mbusd/tests/greatest

greatest

A testing system for C, contained in 1 file.

Key Features

• Small, Portable, Lightweight

  greatest doesn't depend on anything beyond ANSI C89, and the test scaffolding should build without warnings when compiled with -Wall -Wextra -pedantic. It is under 1,000 LOC (SLOCCount), and does no dynamic allocation.

• Permissive License

  greatest is released under the ISC License. You can use it freely, even for commercial purposes.

• Easy To Set Up

  To use, just #include "greatest.h" in your project. There is very little boilerplate. Most features are optional.

• Un-Opinionated

  When a command-line test runner is useful, greatest can provide one, but it can also run as part of other programs. It doesn't depend on a particular build system or other tooling, and should accommodate a variety of testing approaches. It actively avoids imposing architectural choices on code under test. While greatest was designed with C in mind, it attempts to be usable from C++.

• Modular

  Tests can be run individually, or grouped into suites. Suites can share common setup, and can be in distinct compilation units.

• Low Friction

  Specific tests or suites can be run by name, for focused and rapid iteration during development. greatest adds very little startup latency.

There are some compile-time options, and slightly nicer syntax for parametric testing (running tests with arguments) if compiled with a C99 or later language standard.

I wrote a blog post with more information.

theft, a related project, adds property-based testing.

Basic Usage

#include "greatest.h"

/* A test runs various assertions, then calls PASS(), FAIL(), or SKIP(). */
TEST x_should_equal_1(void) {
    int x = 1;
    ASSERT_EQ(1, x);                              /* default message */
    ASSERT_EQm("yikes, x doesn't equal 1", 1, x); /* custom message */
    /* printf expected and actual values as "%d" if they differ */
    ASSERT_EQ_FMT(1, x, "%d");
    PASS();
}

/* Suites can group multiple tests with common setup. */
SUITE(the_suite) {
    RUN_TEST(x_should_equal_1);
}

/* Add definitions that need to be in the test runner's main file. */
GREATEST_MAIN_DEFS();

int main(int argc, char **argv) {
    GREATEST_MAIN_BEGIN();      /* command-line options, initialization. */

    /* Individual tests can be run directly. */
    /* RUN_TEST(x_should_equal_1); */

    /* Tests can also be gathered into test suites. */
    RUN_SUITE(the_suite);

    GREATEST_MAIN_END();        /* display results */
}

Output:

$ make simple && ./simple
cc -g -Wall -Werror -pedantic    simple.c   -o simple

* Suite the_suite:
.
1 test - 1 passed, 0 failed, 0 skipped (5 ticks, 0.000 sec)

Total: 1 test (47 ticks, 0.000 sec), 3 assertions
Pass: 1, fail: 0, skip: 0.

Test cases should call assertions and then end in PASS(), SKIP(), FAIL(), or one of their message variants (e.g. SKIPm("TODO");). If there are any test failures, the test runner will return 1, otherwise it will return 0. (Skips do not cause a test runner to report failure.)

Tests and suites are just functions, so normal C scoping rules apply. For example, a test or suite named "main" will have a name collision.

(For more examples, look at example.c and example_suite.c.)

Filtering By Name

greatest runs all tests by default, but can be configured to only run suites or tests whose names contain a filter string, and/or exclude tests whose name contains a filter string. When test name filtering and exclusion are used together, exclusion takes precedence.

void greatest_set_suite_filter(const char *name);
void greatest_set_test_filter(const char *name);
void greatest_set_test_exclude(const char *name);

These correspond to the following command line test runner options:

`-s SUITE`:   Only run suites whose names contain the string "SUITE"
`-t TEST`:    Only run tests whose names contain the string "TEST"
`-x EXCLUDE`: Exclude tests whose names contain the string "EXCLUDE"

For example, to run any tests with "tree" in the name, in suites with "pars" in the name (such as "parser"), but exclude any tests whose names also contain "slow":

./test_project -s pars -t tree -x slow

Available Assertions

Assertions fail the current test unless some condition holds. All assertions have a "message" variant (with an m suffix), which takes a custom failure message string as their first argument. For example, the assertion ASSERT_EQ(apple, orange); could instead be used like ASSERT_EQm("these should match", apple, orange). Non-message assertions create a default message.

ASSERT(COND)

Assert that COND evaluates to a true value.

ASSERT_FALSE(COND)

Assert that COND evaluates to a false value.

ASSERT_EQ(EXPECTED, ACTUAL)

Assert that EXPECTED == ACTUAL. To compare with a custom equality test function, use ASSERT_EQUAL_T instead. To print the values if they differ, use ASSERT_EQ_FMT.

ASSERT_EQ_FMT(EXPECTED, ACTUAL, FORMAT)

Assert that EXPECTED == ACTUAL. If they are not equal, print their values using FORMAT as the printf format string.

For example: ASSERT_EQ_FMT(123, result, "%d");

Note: EXPECTED and ACTUAL will be evaluated more than once on failure, so they should not be a function call with side effects. (Since their type is not known by the macro, they cannot be captured in a local variable.)

ASSERT_IN_RANGE(EXPECTED, ACTUAL, TOLERANCE)

Assert that ACTUAL is within EXPECTED +/- TOLERANCE, once the values have been converted to a configurable floating point type (GREATEST_FLOAT).

ASSERT_STR_EQ(EXPECTED, ACTUAL)

Assert that the strings are equal (i.e., strcmp(EXPECTED, ACTUAL) == 0).

ASSERT_STRN_EQ(EXPECTED, ACTUAL, SIZE)

Assert that the first SIZE bytes of the strings are equal (i.e., strncmp(EXPECTED, ACTUAL, SIZE) == 0).

ASSERT_MEM_EQ(EXPECTED, ACTUAL, SIZE)

Assert that the first SIZE bytes of memory pointed to by EXPECTED and ACTUAL are equal. If the memory differs, print a hexdump and highlight the lines and individual bytes which do not match.

ASSERT_ENUM_EQ(EXPECTED, ACTUAL, ENUM_STR_FUN)

Assert that the enum value EXPECTED is equal to ACTUAL. If not, convert each enum value to a string using ENUM_STR_FUN before printing them.

ENUM_STR_FUN should have a type like:

const char *some_enum_str(enum some_enum x);

ASSERT_EQUAL_T(EXPECTED, ACTUAL, TYPE_INFO, UDATA)

Assert that EXPECTED and ACTUAL are equal, using the greatest_equal_cb function pointed to by TYPE_INFO->equal to compare them. The assertion's UDATA argument can be used to pass in arbitrary user data (or NULL). If the values are not equal and the TYPE_INFO->print function is defined, it will be used to print an "Expected: X, Got: Y" message.

ASSERT_OR_LONGJMP(COND)

Assert that COND evaluates to a true value. If not, then use longjmp(3) to immediately return from the test case and any intermediate function calls. (If built with GREATEST_USE_LONGJMP defined to 0, then all setjmp/longjmp-related functionality will be compiled out.)

Random Shuffling

Groups of suites or tests can be run in random order by using GREATEST_SHUFFLE_SUITES and GREATEST_SHUFFLE_TESTS, respectively. This can help find and eliminate coupling between tests.

The shuffling depends on the seed and the test/suite count, so a consistent seed will only lead to reproducible ordering until the group's count changes.

Shuffling suites:

SHUFFLE_SUITES(seed, {
    RUN_SUITE(suite1);
    RUN_SUITE(suite2);
    RUN_SUITE(suite3);
    RUN_SUITE(suite4);
    RUN_SUITE(suite5);
});

Shuffling tests:

SHUFFLE_TESTS(seed, {
    RUN_TEST(test_a);
    RUN_TEST1(test_b, 12345);
    RUN_TEST(test_c);
    RUN_TESTp(test_d, "some_argument");
    RUN_TEST(test_e);

});

Note: Any other code inside the block will be executed several times. The shuffling macro expands to a loop with (count + 1) iterations -- the first pass counts, and the following passes only execute the next chosen suite/test. In particular, avoid running tests directly inside of a SHUFFLE_SUITES block (without a suite), because the test will run over and over.

Sub-Functions

Because of how PASS(), ASSERT(), FAIL(), etc. are implemented (returning a test result enum value), calls to functions that use them directly from test functions must be wrapped in CHECK_CALL:

TEST example_using_subfunctions(void) {
    CHECK_CALL(less_than_three(5));
    PASS();
}

This is only necessary if the called function can cause test failures.

Command Line Options

Test runners build with the following command line options:

Usage: (test_runner) [--help] [-hlfv] [-s SUITE] [-t TEST]
  -h, --help  print this Help
  -l          List suites and tests, then exit (dry run)
  -f          Stop runner after first failure
  -v          Verbose output
  -s SUITE    only run suite w/ name containing SUITE substring
  -t TEST     only run test w/ name containing TEST substring
  -t EXCLUDE  exclude tests containing string EXCLUDE substring

Any arguments after -- will be ignored.

If you want to run multiple test suites in parallel, look at parade.

These command line options are processed by GREATEST_MAIN_BEGIN();.

Aliases

Most of the macros have prefixed and unprefixed forms. For example, SUITE is the same as GREATEST_SUITE.

Check the source for the list -- search for #if GREATEST_USE_ABBREVS.

These aliases can be disabled by #define-ing GREATEST_USE_ABBREVS to 0.

Color Output

If you want color output (PASS in green, FAIL in red, etc.), you can pipe the output through the included greenest script in contrib/:

$ ./example -v | greenest

(Note that greenest depends on a Unix-like environment.)

greatest itself doesn't have built-in coloring to stay small and portable.