docs/os/modules/testutil/test_assert.md

## <font color="F2853F" style="font-size:24pt"> TEST_ASSERT</font>

```no-highlight
TEST_ASSERT(expression, fail_msg, ...)
```
```no-highlight
TEST_ASSERT_FATAL(expression, fail_msg, ...)
```

Asserts that the specified condition is true.  If the expression is true, nothing gets reported. *fail_msg* will be printed out if the expression is false. The expression argument is mandatory; the rest are optional.  The fail_msg argument is a printf format string which specifies how the remaining arguments are parsed.

`TEST_ASSERT_FATAL()` causes the current test case to be aborted, if expression fails.

#### Arguments

| Arguments | Description |
|-----------|-------------|
| expression | Condition being tested. If it fails, test is considered a failure, and a message is printed out. |
| fail_msg | Pointer to C string that contains a format string that follows the same specifications as format in printf. |
| ... | Depending on the format string, the function may expect either a sequence of additional arguments to be used to replace a format specifier in the format string or a variable arguments list. va_list is a special type defined in <cstdarg> in stdarg.h. |

#### Returned values

None

#### Notes

While `console_printf`, with its well understood formatting options in C, is more convenient and easy on the eyes than the raw output of `console_write`, the associated code size is considerably larger.

#### Example
Example #1:

```no-highlight
TEST_CASE(config_test_insert)
{
    int rc;

    rc = conf_register(&config_test_handler);
    TEST_ASSERT(rc == 0);
}
```

Example #2:

```no-highlight
TEST_CASE(nffs_test_unlink)
{
    int rc;

    ....
    
    rc = nffs_format(nffs_area_descs);
    TEST_ASSERT_FATAL(rc == 0);

    ....
}
```

Example #3:

```no-highlight

static int 
cbmem_test_case_1_walk(struct cbmem *cbmem, struct cbmem_entry_hdr *hdr, 
        void *arg)
{
    ....

    rc = cbmem_read(cbmem, hdr, &actual, 0, sizeof(actual));
    TEST_ASSERT_FATAL(rc == 1, "Couldn't read 1 byte from cbmem");
    TEST_ASSERT_FATAL(actual == expected, 
            "Actual doesn't equal expected (%d = %d)", actual, expected);

    ....
}
```