ziomock

Test mocks for Zig. Call trackers, string spies, return mocks, error mocks — zero dependencies.

The pitch

Lightweight test doubles for Zig. Track function calls, spy on string arguments, mock return values and errors.

const ziomock = @import("ziomock");

// Track how many times something was called
var tracker: ziomock.CallTracker(10) = .{};
tracker.record();
tracker.record();
try std.testing.expect(tracker.wasCalledN(2));

// Spy on string arguments
var spy: ziomock.StringSpy(10) = .{};
spy.record("hello");
try std.testing.expect(spy.wasCalledWith("hello"));

// Mock a return value
var mock = ziomock.ReturnMock(u32).init(42);
const val = mock.call(); // 42

// Mock errors: fail N times then succeed
var err_mock = ziomock.ErrorMock(u32).init(2, 99);
const result = err_mock.call(); // error.MockError
const result2 = err_mock.call(); // error.MockError
const ok = try err_mock.call();  // 99

Install

zig fetch --save git+https://github.com/deblasis/ziomock

Then in your build.zig:

const dep = b.dependency("ziomock", .{
    .target = target,
    .optimize = optimize,
});
exe.root_module.addImport("ziomock", dep.module("ziomock"));

Requires Zig 0.16.

API

• CallTracker(max).record() / .callCount() / .wasCalledN(n)
• StringSpy(max).record(s) / .wasCalledWith(s)
• ReturnMock(T).init(value) / .call()
• ErrorMock(T).init(fail_count, value) — fail N times then succeed

Compatibility

• Zig: 0.16.0
• Platforms: Linux, macOS, Windows
• Breaking changes: follows Semantic Versioning. Minor versions add features, patch versions fix bugs.

License

MIT. Copyright (c) 2026 Alessandro De Blasis.