# tests

Two ways to write tests, in one project.

```sh
cd examples/tests
crafter-build test
```

Layout:

```
mylib/MyMath.cppm                  # the library being tested
project.cpp                        # declares the library

tests/Smoke/main.cpp               # zero-config test (no project.cpp)
tests/UnitMyMath/main.cpp          # test that links MyMath and exercises it
tests/UnitMyMath/project.cpp       # required for tests with deps
```

## Auto-discovery

Each `tests/<Name>/` directory becomes a test. Three layers, escalate only as needed:

1. **`tests/<Name>/main.cpp`** with no `project.cpp` — discovery synthesizes a Configuration. Top-level `*.cpp` files become implementations, `interfaces/*.cppm` become module interfaces. `Smoke` is this case.
2. **`tests/<Name>/project.cpp`** — full control. Use this when you need defines, dependencies, or non-default targets. `UnitMyMath` is this case (it depends on `MyMath`).
3. Folders starting with `_` or `.` are skipped (e.g. `tests/_shared/` for cross-test helpers).

## Test conventions

- Exit code `0` = pass, anything nonzero = fail, **`77` = skipped** (autoconf convention). Use `std::exit(77)` for runtime skips like "tool not on PATH".
- Each test runs in its own subprocess; a segfault doesn't take down the runner.
- Default timeout is 60 s (`crafter-build test --timeout=N` overrides).
- Filter by name: `crafter-build test 'Unit*'`. List without running: `crafter-build test --list`.

## Linking the parent project

`UnitMyMath/project.cpp` shows how a test links the project's own library:

```cpp
cfg.dependencies = { ParentLib("MyMath") };
```

`ParentLib("name")` looks up a `Configuration*` in the parent project (the root project's own config + its dependency graph) by `Configuration::name`. The fixture's project.cpp can omit `cfg.path`, `cfg.name`, etc. — the discovery loop fills folder-derived defaults.

## Cross-target test runs

Tests parse `--target=...` from the project args you pass on the command line:

```sh
crafter-build test --target=x86_64-w64-mingw32 --runner=cmd:wine
```

`--runner=<spec>` overrides the per-target runner for this invocation. Useful specs: `local`, `cmd:<command>` (prefix-exec, e.g. `cmd:wine`, `cmd:qemu-aarch64`), `ssh:<host>[:<remoteDir>]`, `sshwin:<host>[:<remoteDir>]`. Or persist via env var: `CRAFTER_BUILD_RUNNER_<normalized_target>=<spec>`.