using Shouldly;
using Xunit;

namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.ParityTests;

/// <summary>
///     Shape tests for the <see cref="ParityHarness"/> itself — these run regardless of
///     dev-environment availability. The scenario tests in PR 5.2–5.8 carry the actual
///     parity assertions and are guarded by <see cref="ParityHarness.RequireBoth"/>.
/// </summary>
[Collection(nameof(ParityCollection))]
public sealed class HarnessShapeTests
{
    private readonly ParityHarness _h;
    public HarnessShapeTests(ParityHarness h) => _h = h;

    [Fact]
    public void Harness_records_a_skip_reason_for_each_unavailable_backend()
    {
        // Either the backend resolved (driver != null, skipReason == null) or it didn't
        // (driver == null, skipReason populated). Asserting the invariant lets the parity
        // matrix doc (PR 5.W) faithfully report "n/a, reason: ..." for unreachable rigs.
        (_h.LegacyDriver is null).ShouldBe(_h.LegacySkipReason is not null);
        (_h.MxGatewayDriver is null).ShouldBe(_h.MxGatewaySkipReason is not null);
    }

    [Fact]
    public async Task RunOnAvailableAsync_yields_one_entry_per_resolved_backend()
    {
        var calls = await _h.RunOnAvailableAsync(
            (_, _) => Task.FromResult(1), CancellationToken.None);

        var expected = (_h.LegacyDriver is null ? 0 : 1) + (_h.MxGatewayDriver is null ? 0 : 1);
        calls.Count.ShouldBe(expected);
    }
}