"libc headers not available" when building test

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1

I’m trying to run a test in my project with --test-filter but it fails with this error

src/root.zig:19:15: error: C import failed
pub const c = @cImport({
              ^~~~~~~~
src/root.zig:19:15: note: libc headers not available; compilation does not link against libc
referenced by:
    c: src/apu/buffer.zig:2:33
    apu.buffer.SampleBuffer: src/apu/buffer.zig:11:13
    14 reference(s) hidden; use '-freference-trace=16' to see all references
.zig-cache/o/ecb56e828e2cd32e919574aae0b45d08/cimport.h:1:10: error: 'SDL3/SDL.h' file not found
#include <SDL3/SDL.h>

I’ve tried using this code, but it didn’t work:

    const mod_tests = b.addTest(.{
        .root_module = mod,
    });
    const sdl_lib_tests = sdl_dep.artifact("SDL3_test");
    mod_tests.linkLibrary(sdl_lib_tests);

    // A run step that will run the test executable.
    const run_mod_tests = b.addRunArtifact(mod_tests);

    // Creates an executable that will run `test` blocks from the executable's
    // root module. Note that test executables only test one module at a time,
    // hence why we have to create two separate ones.
    const exe_tests = b.addTest(.{
        .root_module = exe.root_module,
    });
    exe_tests.linkLibrary(sdl_lib_tests);

    // A run step that will run the second test executable.
    const run_exe_tests = b.addRunArtifact(exe_tests);

I’ve already used .link_libc = true on the mod creation.

I’m using this for the SDL dependency. The full build.zig can be found here.

2

This implies you’re trying to run zig test directly instead of zig build test. If so, your build.zig is not being used at all.

3

Yes, I’m running zig test directly. Then, how can I work around this problem?

6

My suggestion would be to use zig build test and add test filter support as an option:

    const test_filters = b.option([]const []const u8, "test-filter", "Skip tests that do not match any filter") orelse &[0][]const u8{};

    const mod_tests = b.addTest(.{
        .root_module = mod,
        .filters = test_filters,
    });

    const exe_tests = b.addTest(.{
        .root_module = exe.root_module,
        .filters = test_filters,
    });

So then you’d do:

zig build test -Dtest-filter=your_filter

If you want to see what you’d need to do to run the same thing with zig test directly, you can pass --verbose:

zig build test -Dtest-filter=your_filter --verbose

which will print the commands run by the build system.

1 Like
7

That worked thanks! By the way, do you know how to configure launch.json in VSCode so that can debug individual tests? I think it uses the zig test command by default so it’s going to throw the same error.

8

For debugging tests as far as I know you can only debug the generated test executable, so specify it as any normal program. I assume filtering tests will prevent those tests from being included in the final executable and if not you can always set a breakpoint.

Make sure you’re compiling with LLVM for proper debugging support and if you’re using lldb use the pretty printer zig/tools/lldb_pretty_printers.py at master · ziglang/zig · GitHub to get proper array printing and other nice stuff.

I use zed for debugging and I think they use a different but similar format for debugging as vscode. here is a snippet I use, hope it helps.

  {
    "adapter": "CodeLLDB",
    "label": "example",
    "request": "launch",
    "name": "example",
    "program": "./zig-out/bin/example",
    "args": [],
    "stopOnEntry": false,
    "cwd": "${ZED_WORKTREE_ROOT}",
    "initCommands": ["command source ${ZED_WORKTREE_ROOT}/.lldbinit"]
  }
9

there is an lldb fork for the custom backend(s), but it requires building it from source, which isn’t bad, but it is slow.

I find that fork to be nicer to use, but not by a lot.

wiki for zig and lldb for more information about both.

1 Like
10

I’ve had to setup something like this in VSCode to filter the tests by name:

  • launch.json:
{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "type": "lldb",
            "request": "launch",
            "name": "Debug Executable",
            "args": [
                "./sample_roms/test.nes"
            ],
            "cwd": "${workspaceFolder}",
            "program": "./zig-out/bin/ness"
        },
        {
            "name": "Debug Filtered Test",
            "type": "lldb",
            "request": "launch",
            "program": "${workspaceFolder}/zig-out/tests/mod-test",
            "args": [],
            "cwd": "${workspaceFolder}",
            "preLaunchTask": "build-filtered-test",
        }
    ],
}
  • tasks.json:
{
  "version": "2.0.0",
  "tasks": [
    {
      "label": "build-filtered-test",
      "type": "shell",
      "command": "zig",
      "args": [
        "build",
        "test",
        "-Dtest-filter=${input:testFilter}",
        "-Dno-run"
      ],
      "group": {
        "kind": "build",
        "isDefault": true
      }
    }
  ],
      "inputs": [
        {
            "id": "testFilter",
            "type": "promptString",
            "description": "Enter test name",
            "default": ""
        }
    ]
}
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