Assert-based tests in C

A test is a function full of asserts, called from main. No framework needed.

#include <assert.h>
#include <stdio.h>

static size_t count_char(const char *text, char target) {
    size_t n = 0;
    for (; *text; text++) {
        if (*text == target) {
            n++;
        }
    }
    return n;
}

static void test_counts_repeats(void) {
    assert(count_char("mississippi", 's') == 4);
    assert(count_char("mississippi", 'm') == 1);
}

static void test_handles_absence(void) {
    assert(count_char("abc", 'z') == 0);
    assert(count_char("", 'a') == 0);
}

int main(void) {
    test_counts_repeats();
    test_handles_absence();
    printf("all tests passed\n");
    return 0;
}

How it works

1. Each test names one behavior and asserts it.
2. main runs them and reports when all have passed.
3. A failing assert aborts and names the file and line.

Keywords and builtins used here

• char
• const
• count_char
• for
• if
• int
• main
• return
• size_t
• static
• test_counts_repeats
• test_handles_absence
• void

The run, in numbers

Lines

29

Characters to type

534

Tokens

163

Three-star pace

110 tpm

At the three-star pace of 110 tokens a minute, this run takes about 89 seconds.

Type this snippet

Step 1 of 2 in Encore, step 10 of 11 in APIs, errors & testing.

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