nala 0.180.0

A test framework for C projects.

🦁 Nala

A delightful test framework for C projects.

Based on Narwhal and Narmock.

Features

• Automatic test discovery

• Use the same generic assertions everywhere

• Assertion failures reported as diffs

• Powerful mocking

• Easy-to-use output capturing utilities

• Traceback(s) on failure

• Works well with errors reported by sanitizers

• Test isolation with fork()

• Only run tests matching given pattern

• Automatic build and run on file change

• Optional parallel test execution to save time

• Amalgamated source and header files ready to drop in your project

• JSON test report

Installation

It’s recommended to install Nala with pip. Only Python 3 is supported.

$ pip install nala

Alternatively, if mocking is not needed, you can download the amalgamated header and source files:

• nala.h

• nala.c

Drop the two files in your project, make sure nala.c is compiled and linked just like the other source files of your test program and you should be good to go.

Getting started

Use nala init foo to create a folder foo with two test files, test_assertions.c and test_time.c. The first uses all assertions and captures output, and the second mocks the time function.

$ nala init foo
Run 'make -C foo' to build and run all tests!

The assertions tests looks like this:

#include "nala.h"

TEST(assertions)
{
    int i;
    int array[] = { 1, 5, 2 };

    ASSERT_EQ(NULL, NULL);
    ASSERT_NE(1, 2);
    ASSERT_LT(1.0, 2.0);
    ASSERT_LE(1, 1);
    ASSERT_GT(2L, 1L);
    ASSERT_GE(1, 1);
    ASSERT_TRUE(true);
    ASSERT_FALSE(false);
    ASSERT_SUBSTRING("12345", "34");
    ASSERT_NOT_SUBSTRING("12345", "4567");
    ASSERT_MEMORY_EQ("abcd", "abcd", 5);
    ASSERT_FILE_EQ("test_assertions.c", "test_assertions.c");
    ASSERT_ARRAY_EQ(array, array, sizeof(array));
    ASSERT_FUNCTION_POINTER_EQ(assertions, assertions);
    ASSERT_FUNCTION_POINTER_NE(assertions, NULL);
    ASSERT(1 == 1);

    CAPTURE_OUTPUT(output, errput) {
        printf("output!\n");
        fprintf(stderr, "errput!\n");
    }

    ASSERT_EQ(output, "output!\n");
    ASSERT_EQ(errput, "errput!\n");

    for (i = 0; i < 3; i++) {
        WITH_MESSAGE("i: %d", i) {
            ASSERT_EQ(array[i], array[i]);
        }
    }
}

And the time tests:

#include <time.h>
#include "nala.h"

TEST(mock_time)
{
    time_mock_once(42);

    ASSERT_EQ(time(NULL), 42);
}

Build and run all tests with make -s -C foo.

Build all tests but only run those whose name contains time. This is done by giving ARGS=time.

Run make -s -C foo auto to build and run all tests automatically when any source file in your project is modified. With the command running, make the time test fail by returning 41 instead of 42 from the time mock.

#include <time.h>
#include "nala.h"

TEST(mock_time)
{
    time_mock_once(41);

    ASSERT_EQ(time(NULL), 42);
}

Notice how the test is built and run automatically.

Create a code coverage report and open it with Firefox.

$ make -s -C foo coverage
Code coverage report: /home/erik/workspace/nala/foo/build/coverage/index.html
$ firefox /home/erik/workspace/nala/foo/build/coverage/index.html

API

Below is a list of all macros and functions in the API. They are all defined/declared in include/nala.h.

Assertions

ASSERT_EQ(actual, expected);                  // Assert that given characters, numbers, pointers or
                                              // strings are equal.
ASSERT_NE(actual, expected);                  // Assert that given characters, numbers, pointers or
                                              // strings are not equal.
ASSERT_LT(actual, expected);                  // Assert that actual is less than expected.
ASSERT_LE(actual, expected);                  // Assert that actual is less than or equal to expected.
ASSERT_GT(actual, expected);                  // Assert that actual is greater than expected.
ASSERT_GE(actual, expected);                  // Assert that actual is greater than or equal to
                                              // expected.
ASSERT_TRUE(actual);                          // Assert that given value is true.
ASSERT_FALSE(actual);                         // Assert that given value is false.
ASSERT_SUBSTRING(haystack, needle);           // Assert that given haystack string contains given
                                              // needle string.
ASSERT_NOT_SUBSTRING(haystack, needle);       // Assert that given haystack string does not contain
                                              // given needle string.
ASSERT_MEMORY_EQ(actual, expected, size);     // Assert that given memory regions are equal.
ASSERT_FILE_EQ(actual, expected);             // Assert that given files are equal.
ASSERT_ARRAY_EQ(actual, expected, size);      // Assert that given arrays are equal.
ASSERT_FUNCTION_POINTER_EQ(actual, expected); // Assert that given function pointers are equal.
ASSERT_FUNCTION_POINTER_NE(actual, expected); // Assert that given function pointers are not equal.
ASSERT(cond);                                 // Assert that given condition is true.

Other macros

FAIL(message);                                // Fail current test with given message.
CAPTURE_OUTPUT(stdout_name, stderr_name);     // A capture output block.
WITH_MESSAGE(format, ...);                    // Additional message on error block. May be nested.

Functions

void *nala_alloc(size_t size);                // Allocate a memory buffer of given size that is
                                              // automatically freed after the test. Always returns
                                              // a valid pointer.
void nala_auto_free(void *buf_p);             // Automatically free given buffer after the test.
                                              // free() is called to free the buffer.
void nala_exit(int status);                   // Performs post-test checks and cleanup, and then
                                              // exits with status 0. The status parameter is
                                              // ignored.

Mocking

Generating mocks

The nala generate_mocks command finds mocked functions in your test code and generates nala_mocks.h, nala_mocks.c and nala_mocks.ldflags. The first two files declare and define mocks, while the last file contains linker flags.

Use --rename-parameters-file to rename function parameters, often useful when mocking standard library functions. If not given, Nala renames a few function parameters by default. Also, any __-prefix is removed from all parameters.

Use --no-rename-parameters not to rename any function parameters. Overrides --rename-parameters-file.

Use --no-implementation when the implementation of functions matching given Unix shell-style wildcards pattern are not available in the binary (and therefore should not be called by the generated code, as the linker would give a relocation error). This option may be given multipe times. An alternative to using this option is to manually implement the missing functions. Here is an example implementation of foo() that makes the test fail if called.

int foo()
{
    FAIL("No real implementation available!\n");

    return (0);
}

Use --no-real-variadic-functions not to add any real variadic functions. Nala adds a few variadic functions by default, given that they are mocked.

Here is an example of how to generate mocks:

$ nala cat *.c | gcc -DNALA_GENERATE_MOCKS -x c -E - | nala generate_mocks

nala cat *.c should only concatenate test source files, not any other source files in your project.

Nala requires test source code to be expanded by the preprocessor. You can directly pipe the output of gcc -DNALA_GENERATE_MOCKS -x c -E - to the command-line utility.

Mocking object-internal function calls

The GNU linker ld wrap feature (--wrap=<symbol>) does not wrap object-internal function calls. As Nala implements mocking by wrapping functions, object-internal function calls can’t be mocked just using the linker. To mock these, after compilation, run nala wrap_internal_symbols ... for each object file, and then pass them to the linker.

Also, local (static) functions can’t be mocked, only global functions can!

%.o: %.c
        $(CC) -o $@ $<
        nala wrap_internal_symbols nala_mocks.ldflags $@

Mock API

A function mock will call the real implementation by default. Use the functions below to control mock object behaviour.

Variadic functions will not call the real implementation by default. Give --implementation to nala generate_mocks to generate calls to the real function (taking a va_list instead of ...).

There are plenty of mock-examples in the examples folder. All inline examples below can also be found in the mock_api_examples example.

For all functions

<params> is all char-pointer (string) and primitive type parameters of the mocked function.

Same behaviour for every call.

void FUNC_mock(<params>, <res>);     // check parameters and return
void FUNC_mock_ignore_in(<res>);     // ignore parameters and return
void FUNC_mock_none();               // no calls allowed
void FUNC_mock_implementation(*);    // replace implementation
void FUNC_mock_real();               // real implementation

An example:

/* int foo(int value); */

TEST(foo_every_call)
{
    foo_mock(1, 2);

    /* All calls to foo() expects its parameter to be 1 and returns 2. */
    ASSERT_EQ(foo(1), 2);
    ASSERT_EQ(foo(1), 2);
}

Per call control.

int FUNC_mock_once(<params>, <res>); // check parameters and return once (per call)
                                     // returns a mock instance handle
int FUNC_mock_ignore_in_once(<res>); // ignore parameters and return once (per call)
                                     // returns a mock instance handle
void FUNC_mock_real_once();          // real implementation once (per call)

An example:

/* int foo(int value); */

TEST(foo_per_call)
{
    foo_mock_once(1, 2);
    foo_mock_once(4, 5);

    /* First call to foo() expects its parameter to be 1 and returns 2. */
    ASSERT_EQ(foo(1), 2);

    /* Second call to foo() expects its parameter to be 4 and returns 5. */
    ASSERT_EQ(foo(4), 5);

    /* Third call will fail and the test will end. */
    foo(10);
}

Changes the behaviour of currect mock object (most recent *_mock() or *_mock_once() call). Works for both per call and every call functions above.

void FUNC_mock_set_errno(int);       // errno on return, 0 by default
void FUNC_mock_set_callback(*);      // additional checks and/or actions
                                     // called just before returning from the mock

An example:

/* int foo(int value); */

TEST(foo_set_errno)
{
    foo_mock_once(1, 2);
    foo_mock_set_errno(EINVAL);

    ASSERT_EQ(foo(1), 2);
    ASSERT_EQ(errno, EINVAL);
}

Get per call input parameters.

*FUNC_mock_get_params_in(int);       // get input parameters for given mock instance
                                     // handle

An example:

/* typedef void (*callback_t)(void); */
/* void bar(callback_t callback); */

static void fie(void)
{
    printf("fie() called!\n");
}

TEST(bar_get_params_call_callback)
{
    int handle;

    handle = bar_mock_once();

    bar(fie);

    /* Call the callback (calls fie()). */
    bar_mock_get_params_in(handle)->callback();
}

For pointer and array function parameters

Changes the behaviour of currect mock (most recent *_mock() or *_mock_once() call). Works for both per call and every call functions above.

void FUNC_mock_set_PARAM_in(*, size_t);  // check on input
void FUNC_mock_set_PARAM_in_assert(*);   // custom assert function on input
void FUNC_mock_set_PARAM_in_pointer(*);  // check pointer (the address) on input
void FUNC_mock_set_PARAM_out(*, size_t); // value on return
void FUNC_mock_set_PARAM_out_copy(*);    // custom output copy function

An example:

/* struct foo_t { char *string_p }; */

/* void fum(int *value_p, struct foo_t *foo_p); */

static void assert_foo_string(struct foo_t *actual_p,
                              struct foo_t *expected_p,
                              size_t size)
{
    ASSERT_EQ(size, sizeof(*expected_p));
    ASSERT_EQ(actual_p->string_p, expected_p->string_p);
}

TEST(fum_in_out)
{
    int value;
    struct foo_t foo;

    fum_mock_once();

    /* Expect *value_p to be 1 when fum() is called, and assign 2 to
       it before returning. */
    value = 1;
    fum_mock_set_value_p_in(&value, sizeof(value));
    value = 2;
    fum_mock_set_value_p_out(&value, sizeof(value));

    /* Use a custom parameter assert function to check that
       foo_p->string_p is "Hello!"  when fum() is called. */
    foo.string_p = "Hello!";
    fum_mock_set_foo_p_in(&foo, sizeof(foo));
    fum_mock_set_foo_p_in_assert(assert_foo_string);

    value = 1;
    foo.string_p = "Hello!";
    fum(&value, &foo);
    ASSERT_EQ(value, 2);
}

For function parameters part of <params>

Changes the behaviour of currect mock object (most recent *_mock() or *_mock_once() call). Works for both per call and every call functions above.

void FUNC_mock_ignore_PARAM_in();        // ignore on input

An example:

/* void foo(int value); */

TEST(foo_ignore_value)
{
    foo_mock_once(1, 2);
    foo_mock_ignore_value_in();

    ASSERT_EQ(foo(9), 2);
}

For variadic functions

Variadic function mocks are slightly different from the above. Their parameter list is extended with a format string (format) and an ellipsis (...), as shown below.

void FUNC_mock(<params>, <res>, format, ...);
void FUNC_mock_once(<params>, <res>, format, ...);
void FUNC_mock_ignore_in(<res>, format);
void FUNC_mock_ignore_in_once(<res>, format);

The format string supports the following specifiers.

%d  - signed integer
%u  - unsigned integer
%ld - signed long integer
%lu - unsigned long integer
%p  - pointer address
%s  - string

The %p specifier takes no value when calling the mock function, just like pointers are not part of the mock function parameters list. Instead, set pointers after the mock call.

foo_mock(3, "%d%p%s", 5, "the-string");
foo_mock_set_va_arg_in_pointer_at(1, NULL);

The variadic parameters are controlled by index instead of name.

void FUNC_mock_ignore_va_arg_in_at(uint);          // ignore on input
void FUNC_mock_set_va_arg_in_at(uint, *, size_t);  // check on input
void FUNC_mock_set_va_arg_in_assert_at(uint, *);   // custom assert function on input
void FUNC_mock_set_va_arg_in_pointer_at(uint, *);  // check pointer (the address) on input
void FUNC_mock_set_va_arg_out_at(uint, *, size_t); // value on return
void FUNC_mock_set_va_arg_out_copy_at(uint, *);    // custom output copy function

Limitations

• Structs and unions passed by value are ignored.

• va_list parameters are ignored.

• malloc() and free() can’t be mocked if forking and using gcov. They probably can if wrapping __gcov_fork() in an suspend/resume-block.

• static functions can’t be mocked.

• Only primitive data type members are asserted when comparing structs. Pointer and union members are not asserted, and probably never will be.

Debugging tips

Nala executes each test in its own process. This means that following the execution of a test with a debugger can be a bit tricky because debuggers like GDB can only follow a single process at a time.

If you’re using GDB, set a breakpoint at <test>_before_fork and then run the program until it stops at the breakpoint. Before continuing the program execution, tell GDB to follow the forked test process by setting follow-fork-mode to child.

Below are all commands to debug the assertions test in the example above.

$ gdb foo/build/app
(gdb) b assertions_before_fork
(gdb) r
(gdb) set follow-fork-mode child
(gdb) c

The gdb make target starts GDB and runs all commmands listed above. Set the TEST make variable to the test to debug. Both TEST=test_assertions::assertions and TEST=assertions are accepted. The test name may be partialy given, as long as it only matches one test.

$ make -s -C foo gdb TEST=assertions

The test program takes optional arguments as below, which also can be helpful when debugging, especially --print-all-calls.

$ foo/build/app --help
usage: foo/build/app [-h] [-v] [-c] [-a] [-r] [-f] [-j] [<test-pattern>]

Run tests.

positional arguments:
  test-pattern                  Only run tests matching given pattern. '^' matches
                                the beginning and '$' matches the end of the test
                                name.

optional arguments:
  -h, --help                    Show this help message and exit.
  -v, --version                 Print version information.
  -c, --continue-on-failure     Continue on test failure.
  -a, --print-all-calls         Print all calls to ease debugging.
  -r, --report-json-file        JSON test report file (default: report.json).
  -f, --print-test-file-func    Print file:function for exactly one test.
  -j, --jobs                    Run given number of tests in parallel
                                (default: 1).

Compiler flags

Pass -no-pie -g -O0 -fsanitize=address to the compiler for better error reporting.

Read more about sanitizers here: https://en.wikipedia.org/wiki/AddressSanitizer

Other unit test frameworks

Other C unit test frameworks with similar feature set as Nala.

• CMock + Unity

• cmocka

Ideas

New set of generated parameter functions where _in() functions are renamed to _in_buffer(). New _in() functions are added, without the size parameter. Also remove the size parameter from the assert function, as it is seldom used.

void FUNC_mock_set_PARAM_in(*);                 // check on input
void FUNC_mock_set_PARAM_in_buffer(*, size_t);  // check on input
void FUNC_mock_set_PARAM_in_assert(*);          // custom assert function on input
void FUNC_mock_set_PARAM_in_pointer(*);         // check pointer (the address) on input
void FUNC_mock_set_PARAM_out(*);                // value on return
void FUNC_mock_set_PARAM_out_buffer(*, size_t); // value on return
void FUNC_mock_set_PARAM_out_copy(*);           // custom output copy function

An example:

/* struct foo_t { char *string_p }; */

/* void fum(int *value_p, struct foo_t *foo_p); */

static void assert_foo_string(struct foo_t *actual_p, struct foo_t *expected_p)
{
    /* Is size is needed (which is seldom is). */
    ASSERT_EQ(nala_mock_get_param_in_size(), sizeof(*expected_p));
    ASSERT_EQ(actual_p->string_p, expected_p->string_p);
}

TEST(fum_in_out)
{
    int value;
    struct foo_t foo;

    fum_mock_once();

    /* Expect *value_p to be 1 when fum() is called, and assign 2 to
       it before returning. */
    value = 1;
    fum_mock_set_value_p_in(&value);
    value = 2;
    fum_mock_set_value_p_out(&value);

    /* Use a custom parameter assert function to check that
       foo_p->string_p is "Hello!"  when fum() is called. */
    foo.string_p = "Hello!";
    fum_mock_set_foo_p_in(&foo);
    fum_mock_set_foo_p_in_assert(assert_foo_string);

    value = 1;
    foo.string_p = "Hello!";
    fum(&value, &foo);
    ASSERT_EQ(value, 2);
}