How to test a module that depends on other modules

[robust wolf]

I have a module dag that depends on another module sys. The source code works fine, but when I execute my tests for the dag module I get the following error:

src/dag/node.zig:3:21: error: no module named 'sys' available within module test
const sys = @import("sys");

I figured that I just needed to add sys as an import to the test executable in the same way that I added it as an import to the main executable in my build.zig. Here is the code I tried:

const sys = b.createModule(.{
    .root_source_file = .{ .path = "src/sys/sys.zig" },
    .target = target,
    .optimize = optimize,
});

exe.root_module.addImport("sys", sys);
exe_unit_tests.root_module.addImport("sys", sys); // added this line

However, this did not resolve the error. Is this even possible or am I a bad person for trying to put non-unit tests in a file that uses multiple modules?

Minimal example: https://github.com/mitchelldw01/tmp/tree/main

I also have the following code in my test, which did not fix the error.

const testing = std.testing;
testing.refAllDecls(@This());

[random turret]

not sure if this is the best way, but you can do sys.addImport("sys", sys);

oh i think i misunderstood the question. maybe you need to add sys to the dag module?

[robust wolf]

yeah I have sys as import in the dag module, and it works fine in the source code

const dag = b.createModule(.{
    .root_source_file = .{ .path = "src/dag/dag.zig" },
    .target = target,
    .optimize = optimize,
    .imports = &.{
        .{ .name = "diag", .module = diag },
        .{ .name = "sys", .module = sys },
    },
});

exe.root_module.addImport("dag", dag);

[random turret]

could you show how you init exe_unit_tests?

[robust wolf]

just the way zig init does it

// Creates a step for unit testing. This only builds the test executable
// but does not run it.
const exe_unit_tests = b.addTest(.{
    .root_source_file = .{ .path = "src/main.zig" },
    .target = target,
    .optimize = optimize,
});

const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);

// Similar to creating the run step earlier, this exposes a `test` step to
// the `zig build --help` menu, providing a way for the user to request
// running the unit tests.
const test_step = b.step("test", "Run unit tests");
test_step.dependOn(&run_exe_unit_tests.step);

[random turret]

not sure but you might have to add the dag module to exe_unit_tests?

[robust wolf]

I'm doing that like this exe_unit_tests.root_module.addImport("dag", dag); but no luck

[random turret]

if you add dag, can you access sys through it?

ie const sys = @import("dag").sys;

[robust wolf]

nope I can't

I made this minimal example https://github.com/mitchelldw01/tmp/tree/main/src if you felt like seeing the issue better. Running zig test src/dag.zig doesn't work

[random turret]

if its not too big, maybe post you whole buld.zig. otherwise could you post it to https://zigbin.io/ ?

[robust wolf]

build.zig in that repo ^

[random turret]

oh nevermind. thanks will have a look

oic. you're running zig test src/dag.zig. if you want to just test the one file on the command line, you'll need to also add flags for the module.

it appears that zig build test works fine. if you want to see the flags, run zig build test --verbose

does that make sense? the issue was that you're using zig test ... which doesn't use the build.zig

you need to run zig build test for that to happen

[robust wolf]

zig build test doesn't look like it's running the actual test though unless I'm confused

The output of zig built test --verbose looks the same before and after adding testing.expectEqual(1, 2); to my test just to make it fail

[random turret]

try adding zig build test --summary all to see a report

it might be cached in which case it won't run.

and if you want to make sure it always runs, even when cached: run_exe_unit_tests.has_side_effects = true;

[random turret]

ok i see. sorry i keep missing messages

which file is this in?

[robust wolf]

No worries. I just pushed my updates: I added the line to make the test fail in src/dag.zig. I also added run_exe_unit_tests.has_side_effects = true; to thet build.zig

[random turret]

ok i'll pull and try again.

[robust wolf]

I also commented out the test in main.zig

[random turret]

i think i see the problem. you'll need to reference the files you want to test from a test block in main.zig or whatever file you specify as root_source_file for your tests.

something like this

test {
    _ = @import("dag.zig");
}

[robust wolf]

Oooh that was it for the minimal example. However when I try to do the same in my main project I get the error

src/sys/sys.zig:1:1: error: file exists in multiple modules
src/sys/sys.zig:1:1: note: root of module sys
src/main.zig:112:17: note: imported from module root
    _ = @import("sys/sys.zig");

[random turret]

maybe change that line to @import("sys")

[robust wolf]

yup tried that too but same error

[random turret]

i'm a little worried you might have added some unnecessary stuff at this point. i've been there fighting with the module system before. i would recommend removing all the modules and trying to just import files. and then maybe you can add back modules only where necessary?

[robust wolf]

I made a silly mistake in the main project. sys/sys.zig is the root of the module but didn't contain the tests so I just needed to import the correct file. So your solution worked in my main project as well 🙏

Yeah the module system has been annoying as a zig beginner it just feels more "right" for some things as opposed to importing from files only

[random turret]

good news! yeah i agree. the module system can seem a little restrictive sometimes with the 'multiple modules' error. but i think after a while i stopped having problems with it.