ZX Spectrum

Test suites for ZX Spectrum emulators.

Getting Started

Start by installing the NuGet package into your test project:

dotnet add package MrKWatkins.EmulatorTestSuites.ZXSpectrum

You will then need to create a concrete implementation of the ZXSpectrumTestHarness abstract base class. A Spectrum harness composes a Z80 harness rather than inheriting from it, because the ZX Spectrum contains a Z80 CPU:

public sealed class MySpectrumTestHarness : ZXSpectrumTestHarness
{
    public override Z80TestHarness Z80 { get; } = new MyZ80TestHarness();

    public override void StartFrame()
    {
        // Synchronise the emulator to the start of a Spectrum frame.
    }
}

If your emulator supports cycle or T-state stepping, expose a Z80SteppableTestHarness from Z80. If it only supports instruction-level execution, expose a regular Z80TestHarness; the Spectrum timing tests will use step execution when available and instruction execution otherwise.

Lastly, add unit tests in the framework of your choosing. For example, using NUnit to run the timing tests:

public sealed class TimingTests
{
    [TestCaseSource(nameof(TestCases))]
    public void Timing(TimingTestCase testCase) => testCase.Execute<MySpectrumTestHarness>(TestContext.Progress);

    [Pure]
    public static IEnumerable<TimingTestCase> TestCases() => TimingTestSuite.Instance.TestCases;
}

Timing Tests

The Timing test suite runs a Spectrum timing program and compares the measured R register, loop counter and stack pointer values with the expected values embedded in the test data. It automatically detects whether the emulator behaves like an early-timing or late-timing machine. The 35-37 variants settle from the 48K ROM/BASIC prompt snapshot and then execute the original BASIC statements directly, so they need Spectrum-specific machine timing, including floating-bus behaviour.

The available test suites are:

• Timing