zig/test/link/wasm/extern/build.zig

const std = @import("std");

pub fn build(b: *std.Build) void {
    const test_step = b.step("test", "Test it");
    b.default_step = test_step;

    add(b, test_step, .Debug);
}

fn add(b: *std.Build, test_step: *std.Build.Step, optimize: std.builtin.OptimizeMode) void {
    const exe = b.addExecutable(.{
        .name = "extern",
        .root_module = b.createModule(.{
            .root_source_file = b.path("main.zig"),
            .optimize = optimize,
            .target = b.resolveTargetQuery(.{ .cpu_arch = .wasm32, .os_tag = .wasi }),
        }),
    });
    exe.root_module.addCSourceFile(.{ .file = b.path("foo.c"), .flags = &.{} });
    exe.use_llvm = false;
    exe.use_lld = false;

    const run = b.addRunArtifact(exe);
    run.skip_foreign_checks = true;
    run.expectStdOutEqual("Result: 30");

    test_step.dependOn(&run.step);
}