Skip tests based on preprocessor conditionals in generate_test_runner.rb

[bmoneill]

generate_test_runner.rb does not currently take into account #ifdefs and the like. If you have written a test which targets a specific platform, for example, the build will fail when building on another platform because the runner generates the function declarations anyways.

A working fix could be for the user set environment variables that match the preprocessor definitions, and have generate_test_runner.rb parse #ifdefs/#ifndefs and only generate runner code for the functions that match the conditional. This behavior should probably be enabled via a CLI argument.

[mvandervoord]

Hi. Thanks for the good question. Because the features supported by preprocessors vary so much from tool to tool (as does the notation), this has been a feature that we have always relied on the build system to perform. The build system hands unity a preprocessed version of the test file which is can then use to generate runners for. This is how Ceedling handles it, for example.