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This repository was incorporated into headlock and thus is no longer maintained

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pytest-headlock

Some pytest plugins and helper modules to simplify using headlock with pytest.

Error Reporting Plugin

pytest_headlock will install a plugin called "headlock-report-error". This plugin ensures that when a C-module fails due to a compile-error (i.e. invalid syntax) you will not get a python exception of type CompileError with the corresponing stack trace (which refers into modules of headlock). Instead you get well formatted C error messages like:

==== ERROR IN C SOURCE CODE ===================
C:\Users\user1\Development\project1\tests\file1.c:100: Error 1
C:\Users\user1\Development\project1\tests\file1.c:102: Error 2
C:\Users\user1\Development\project1\tests\file1.c:210: Error 3
===============================================

Debugging Support Plugin

pytest_headlock will install a plugin called "headlock-debug-support". It can be used when you need to debug into a failing C module with the debugger of your IDE.

This plugin creates a file .pytest-headlock/CMakeLists.txt, in the pytest root directory. This CMakeLists file can be incorporated (via add_subdirectory) into your main CMakeLists file.

It creates a shared library project starting with TS_*. you can debug this shared library from your IDE by running the following executable from within any directory of your project (it will search the root directory containing .pytest-headlock automaticially):

python -m pytest_headlock.debug_failed

This module will rerun the first failed test of the last regular pytest run (or the last test at all if no one failed). Furthermore it will ensure that the C code is not build automaticially, as it was already build by your IDE.

Helper Methods

• testsetup_fixture decorator

  Simplifies creation of testsetups as reuable fixtures:

  from headlock import TestSetup, CModule
  from pytest_headlock import testsetup fixture
  
  @testsetup_fixture
  @CModule('test.c')
  class ts(TestSetup):
      def __startup__(ts):
         pass  # will be run BEFORE running test function
      def __shutdown__(ts):
         pass  # will be run AFTER running test function
  
  def test_foo(ts):
      ts.c_func()

• val_ptr() / mem_ptr()

  Convenience method to compare pointers. As in C parameters are passed by-reference (=pointers) instead of by-value. But in headlock comparing pointers means you compare the address they are pointing to. Thus when using a mock framework like unittest.mock.assert_called_*_with() it is hard to check if the passed value is correct.

  To compare the value referred by a pointer it has to be resolved: ts.pointer.ref.val == 123. This can be replaced by val_ptr: val_ptr(ts.pointer) == 123 (mem_ptr will resolve to ts.pointer.ref.mem).

  Assume we have a C function signature void c_func(char * buf, int buf_len); When mocking this function it is pretty easy now to check if a specific value was passed to buf:

  def test_foo(ts):
      ts.c_func = unittest.mock.Mock()
      ### run some C code that calls c_func
      ts.c_func.assert_called_with(mem_ptr(b'test'), 4)