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A test framework for C projects.

Project description

buildstatus coverage codecov

🦁 Nala

A 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

  • 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.

$ pip install nala

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

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 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_SUBSTRING("12345", "34");
    ASSERT_NOT_SUBSTRING("12345", "4567");
    ASSERT_MEMORY_EQ("abcd", "abcd", 5);
    ASSERT_ARRAY_EQ(array, array, sizeof(array));
    ASSERT(1 == 1);

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

    ASSERT_EQ(output, "std!\n");
    ASSERT_EQ(errput, "err!\n");
}

And the time tests:

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

TEST(mock_time)
{
    time_mock_once(42);

    ASSERT_EQ(time(NULL), 42);
}

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

https://github.com/eerimoq/nala/raw/master/docs/build-and-run.png

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

https://github.com/eerimoq/nala/raw/master/docs/build-and-run-one-test.png

Now, make the time test fail to see what an error report looks like.

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

TEST(mock_time)
{
    time_mock_once(41);

    ASSERT_EQ(time(NULL), 42);
}

Build and run all tests. Just as expected, the time test fails since 41 is not equal to 42.

https://github.com/eerimoq/nala/raw/master/docs/build-and-run-assert-eq-fail.png

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

Assertions and other macros

Below is a list of all assertions and other useful macros. They are all defined in include/nala.h.

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_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_ARRAY_EQ(actual, expected, size);      // Assert that given arrays are equal.
ASSERT_FUNCTION_POINTER_EQ(actual, expected); // Assert that given function pointes are equal.
ASSERT_FUNCTION_POINTER_NE(actual, expected); // Assert that given function pointes are not equal.
ASSERT(cond);                                 // Assert that given condition is true.
FAIL(message);                                // Fail current test with given message.
CAPTURE_OUTPUT(stdout_name, stderr_name);     // A capture output block.

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:

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

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 behaviour.

Variadic functions will not call the real implementation by default because an ellipsis (...) can’t be passed to the real function, a va_list is required, which may not be available. Give --implementation to nala generate_mocks to generate calls to the real function (taking va_list).

For all functions

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();               // call real implementation

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();          // call real implementation once (per call)

Change behaviour of currect mock. 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

Get per call input parameters.

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

For selected function parameters

void FUNC_mock_ignore_PARAM_in();        // ignore on input
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

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 (...) in some “every call” and “per call” functions.

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

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.

All commands are shown below for 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

Or using the make target gdb. Set the TEST make variable to the test to debug. Both TEST=test_assertions::assertions and TEST=assertions are accepted.

$ 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

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