nixide/doc/hacking/test-ffi.md

Testing FFI code

If cargo-valgrind is broken, you may run valgrind manually.

1. cd rust; cargo test -v
2. find the relevant test suite executable in the log
   • example: /home/user/src/nix-bindings-rust/rust/target/debug/deps/nix_util-036ec381a9e3fd6d
3. valgrind --leak-check=full <paste the test exe>
4. check that
   • definitely lost: 0 bytes in 0 blocks

Paranoid check

Although normal valgrind tends to catch things, you may choose to enable --show-leak-kinds=all. This will print a few false positive.

Acceptable leaks are those involving (and this may be Linux-specific)

• call_init: static initializers
  • nix::GlobalConfig::Register::Register
  • _GLOBAL__sub_I_logging.cc
  • ...
• new<test::test_main::{closure_env#0}>: a leak in the rust test framework

When in doubt, compare the log to a run with your new test case commented out.