elsa-core/test/unit/Elsa.Activities.UnitTests/Parallel/ParallelTests.cs

using Elsa.Testing.Shared;
using Elsa.Workflows;
using NSubstitute;

namespace Elsa.Activities.UnitTests.Parallel;

public class ParallelTests
{
    [Theory(DisplayName = "Parallel should schedule multiple activities")]
    [InlineData(2)]
    [InlineData(3)]
    [InlineData(4)]
    public async Task Should_Schedule_Multiple_Activities(int activityCount)
    {
        // Arrange
        var activities = Enumerable.Range(1, activityCount)
            .Select(i => new WriteLine($"Activity {i}"))
            .Cast<IActivity>()
            .ToArray();

        var parallel = new Workflows.Activities.Parallel(activities);

        // Act
        var context = await new ActivityTestFixture(parallel).ExecuteAsync();

        // Assert - All activities should be scheduled
        foreach (var activity in activities)
        {
            Assert.True(context.HasScheduledActivity(activity));
        }
    }

    [Fact(DisplayName = "Parallel should not schedule activities when empty")]
    public async Task Should_Not_Schedule_Activities_When_Empty()
    {
        // Arrange
        var parallel = new Workflows.Activities.Parallel();

        // Act
        var context = await new ActivityTestFixture(parallel).ExecuteAsync();

        // Assert - No activities should be scheduled (completion is tested in integration tests)
        var scheduledActivities = context.WorkflowExecutionContext.Scheduler.List().ToList();
        Assert.Empty(scheduledActivities);
    }

    [Fact(DisplayName = "Parallel should schedule a single activity")]
    public async Task Should_Execute_Single_Activity()
    {
        // Arrange
        var activity = Substitute.For<IActivity>();
        var parallel = new Workflows.Activities.Parallel(activity);

        // Act
        var context = await new ActivityTestFixture(parallel).ExecuteAsync();

        // Assert
        Assert.True(context.HasScheduledActivity(activity));
    }

    [Fact(DisplayName = "Parallel should schedule mixed activity types")]
    public async Task Should_Schedule_Mixed_Activity_Types()
    {
        // Arrange
        var writeLine = new WriteLine("Test output");
        var testVar = new Variable<int>("testVar", 0, "testVar");
        var setVariable = new SetVariable<int>(testVar, new Input<int>(42));
        var mockActivity = Substitute.For<IActivity>();

        var parallel = new Workflows.Activities.Parallel(writeLine, setVariable, mockActivity);

        // Act
        var context = await new ActivityTestFixture(parallel).ExecuteAsync();

        // Assert - All activities should be scheduled
        Assert.True(context.HasScheduledActivity(writeLine));
        Assert.True(context.HasScheduledActivity(setVariable));
        Assert.True(context.HasScheduledActivity(mockActivity));
    }

    [Fact(DisplayName = "Parallel should track scheduled children count internally")]
    public async Task Should_Set_Scheduled_Children_Property()
    {
        // Arrange
        var activity1 = new WriteLine("Activity 1");
        var activity2 = new WriteLine("Activity 2");
        var activity3 = new WriteLine("Activity 3");
        var parallel = new Workflows.Activities.Parallel(activity1, activity2, activity3);

        // Act
        var context = await new ActivityTestFixture(parallel).ExecuteAsync();

        // Assert - The parallel activity should track that 3 children were scheduled
        var scheduledChildrenCount = context.GetProperty<int>("ScheduledChildren");
        Assert.Equal(3, scheduledChildrenCount);
    }
}