Testing multiple Zig files in a project

Tests are fully integrated in `Zig`.

You add a `test "my unit test" { .... try std.testing.expect(...)}` along your code and basically run `zig build test` if you declare a test step in your "build.zig" file.

### When you have multiple zig files, how to run all the tests through these files?

I found a Reddit thread on the subject:

```
ou need to have a common file that "references" the testing code for them to be run by a single "addTest" statement in your build file:

src/myLibrary.zig ->

pub const A = @import("A.zig");
pub const B = @import("B.zig");
pub const SomeDataType = @import("C.zig").SomeDataType;

test {
@import("std").testing.refAllDecls(@This());
}
and then in build

const main_tests = b.addTest("src/myLibrary.zig");
main_tests.setBuildMode(mode);

const test_step = b.step("test", "Run library tests");
test_step.dependOn(&main_tests.step);
```

>[!TIP]
>Paraphrasing, the key point is to use a central file where you import all the files and do:
```zig
test {
std.testing.refAllDecls(@This());
}
```

I implemented this in `zhtml`, the `Zig` wrapper of `lexbor`, which should also be wrapped in `Elixir`.

> [!NOTE]
> You must re-export all the functions from the imported module under the namespace of your library to make them available under the library namespace.