MLT - Minimalist Lightweight Testing for C

mlt.h is a simple, header-only C testing framework designed for expressive, colorful, and minimal test suites.
It is ideal for small projects, CI scripts, and educational purposes.

Features

• Colorful output for test results and summaries
• Suite grouping and timing with microsecond precision
• Assertion macros for integers and strings
• String and array utilities
• Sorting helpers for arrays and structs
• Regex helpers (wrappers for POSIX regex)
• No external dependencies except libc

Quick Start

#include "mlt.h"

int main(void) {
    mlt_start();

    mlt_suite_begin("math");
    mlt_assert(2 + 2 == 4);
    mlt_assert(6 / 2 == 3);
    mlt_suite_end();

    mlt_suite_begin("strings");
    char foo[] = "foo";
    char bar[] = "foobar";
    mlt_streq(bar, "foo");
    mlt_strupper(foo);
    mlt_assert(strcmp(foo, "FOO") == 0);
    mlt_suite_end();

    return mlt_finish();
}

API Overview

Available Macros and Utilities

Macro / Function	Description
mlt_start()	Initialize test session and reset counters
mlt_finish()	Complete session, print summary, and return result
mlt_suite_begin(name)	Start a new test suite with the given name
mlt_suite_end()	Complete the current suite and record its time
mlt_assert(expr)	Assert that expr is true
mlt_streq(a, b)	Assert that strings a and b are equal (prefix match)
mlt_strneq(a, b)	Assert that strings a and b are not equal (prefix match)
mlt_strupper(str)	Convert str to uppercase in-place
mlt_strlower(str)	Convert str to lowercase in-place
mlt_strcontains(str, substr)	Returns 1 if substr is found in str, 0 otherwise
mlt_arr_len(arr)	Return the number of elements in array arr
mlt_print_int_arr(arr, n)	Print an array of int of length n
mlt_print_float_arr(arr, n)	Print an array of float of length n
mlt_print_double_arr(arr, n)	Print an array of double of length n
mlt_print_str_arr(arr, n)	Print an array of strings of length n
mlt_define_comparision(type, name, expr)	Define a comparison function for qsort for type/expr
mlt_define_compare_str(name)	Define a string comparison function for qsort
mlt_define_compare_struct(type, field, name)	Define a struct field comparison for qsort
mlt_regex_compile(pattern, regex_ptr)	Compile a POSIX regex pattern
mlt_regex_exec(regex_ptr, text)	Execute a regex match on text
mlt_regex_exec_match(regex_ptr, text, nmatch, pmatch)	Regex match with submatches
mlt_regex_free(regex_ptr)	Free a compiled regex
mlt_debug(...)	Print debug output to stderr
mlt_time_init()	Initialize a timer for a test suite
mlt_time_calc(end, ini)	Calculate elapsed time in seconds (as double)

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Example: Using the Test Framework

See the tests/project_test folder for real-world usage.

Folder Structure

tests/project_test/
├── Makefile
├── src/
│   └── (your source files)
└── tests/
    └── lib_test.c

Example Test (lib_test.c)

#include "config.h"
#include "mlt.h"

int main(void)
{
    mlt_start();

    mlt_suite_begin("lib test");
    mlt_assert(return_number_of_life() == 42);
    mlt_assert(sum_two_numbers(2, 3) == 5);
    mlt_suite_end();

    return mlt_finish();
}

Example Makefile

CC = gcc
CFLAGS = -Wall -Wextra -I./include -I./../../ -g -ggdb
TEST_CFLAGS = -DMLT_TESTING=1

MAIN_SRCS = $(wildcard src/*.c)
TEST_SRCS = $(wildcard tests/*.c)
MAIN_OBJS = $(MAIN_SRCS:.c=.o)
TEST_OBJS = $(TEST_SRCS:.c=.o)

all: main lib_test

%.o: %.c
    $(CC) $(CFLAGS) -c $< -o $@

main: $(MAIN_OBJS)
    $(CC) $^ -o src/$@

lib_test: $(MAIN_SRCS) $(TEST_OBJS)
    $(CC) $(CFLAGS) $(TEST_CFLAGS) $^ -o tests/$@

clean:
    rm -f $(MAIN_OBJS) $(TEST_OBJS) src/main tests/lib_test

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License

This project is licensed under the GNU Lesser General Public License v2.1 or later.
See LICENSE for details.

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Author

Alexandre Mulatinho alex@mulatinho.net