Pamba.Testing 0.3.0

Pamba.Testing

Test utilities for Pamba MVU programs. Calls Update, Validate, and Subscriptions in the correct sequence and returns all results for assertion.

No test framework dependency - works with xUnit, NUnit, MSTest, or any assertion library.

Install

dotnet add package Pamba.Testing

Requires: Pamba. Namespace: Pamba.Testing.

MvuTestRunner

UpdateAndValidate

Calls Update(msg, state), then Validate (if present), then Subscriptions(newState). Returns a TransitionResult containing all outputs for assertion. When Validate returns Invalid, the state reverts, commands are dropped, and CorrectionMessage is set on the result. Does not throw.

TransitionResult<AppState, Msg, Cmd, Sub> result =
    MvuTestRunner.UpdateAndValidate(program, currentState, new Msg.Increment());

Assert.Equal(1, result.State.Count);
Assert.Single(result.Commands);
Assert.IsType<Cmd.Persist>(result.Commands[0]);
Assert.Empty(result.Subscriptions);

InitAndValidate

Calls Init(), then Validate (if present), then Subscriptions(initialState).

TransitionResult<AppState, Msg, Cmd, Sub> result =
    MvuTestRunner.InitAndValidate(program);

Assert.Equal(0, result.State.Count);
Assert.Contains(result.Commands, c => c is Cmd.LoadPreferences);

TransitionResult

public sealed record TransitionResult<TState, TMsg, TCmd, TSub>(
    TState State,
    TMsg? Message,
    TMsg? CorrectionMessage,
    ImmutableArray<TCmd> Commands,
    ImmutableArray<TSub> Subscriptions);

All outputs in a single value. CorrectionMessage is non-null when the validator rejected the transition. Commands and subscriptions are indexable - use result.Commands[0], Assert.Single, Assert.Empty, or the ergonomic extension properties WasRejected, WasAccepted, HasCommands, HasSubscriptions.

MvuScenario

Fluent API for multi-step flow testing. Dispatches a sequence of messages through the program, preserving state between steps. Each step optionally accepts an assertion on the transition result.

MvuScenario.For(program)
    .Dispatch(new Msg.Start(), r =>
    {
      Assert.True(r.State.IsRunning);
      Assert.Single(r.Subscriptions);
    })
    .Dispatch(new Msg.Increment(), r => Assert.Equal(1, r.State.Count))
    .Dispatch(new Msg.Increment())
    .AssertState(s => Assert.Equal(2, s.Count));

API

All methods return the runner for chaining. History includes the Init result at index 0, followed by one entry per Dispatch call.

Related Packages

• Pamba - Framework-agnostic core: contracts, dispatch loop, command/subscription infrastructure.
• Pamba.WinUI - WinUI 3 integration with DispatcherQueue, StateProjectionBase, timer/event subscription helpers, and command debouncer.

Licence

Apache License 2.0