build-flow.api/tests/BuildFlow.Workflow.Tests/Handlers/AddSignerCommandHandlerTests.cs

using BuildFlow.Shared.Domain.Errors;
using FluentAssertions;
using Microsoft.EntityFrameworkCore;
using Workflow.Application.Features.WorkflowTasks.Commands;
using Workflow.Application.Features.WorkflowTasks.Handlers;
using Workflow.Domain.Entities;
using Workflow.Domain.Enums;
using Xunit;

using TaskStatus = global::Workflow.Domain.Enums.TaskStatus;

namespace BuildFlow.Workflow.Tests.Handlers;

public class AddSignerCommandHandlerTests
{
    private static WorkflowDbContext CreateDbContext()
    {
        var options = new DbContextOptionsBuilder<WorkflowDbContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;
        var db = new WorkflowDbContext(options);
        db.SavingChanges += AuditStub.OnSave;
        return db;
    }

    private static WorkflowTask SeedTask(WorkflowDbContext db, Guid assigneeId, TaskStatus status)
    {
        var task = new WorkflowTask
        {
            Id = Guid.NewGuid(),
            InstanceId = Guid.NewGuid(),
            TokenId = Guid.NewGuid(),
            NodeId = Guid.NewGuid(),
            Title = "Approve",
            AssigneeId = assigneeId,
            Status = status
        };
        db.WorkflowTasks.Add(task);
        return task;
    }

    [Fact]
    public async Task AddSigner_Before_DelegatesOriginalAndCreatesSignerTask()
    {
        await using var db = CreateDbContext();
        var current = Guid.NewGuid();
        var signer = Guid.NewGuid();
        var task = SeedTask(db, current, TaskStatus.Pending);
        await db.SaveChangesAsync();

        var handler = new AddSignerCommandHandler(db);
        var command = new AddSignerCommand(task.Id, current, signer, SignPosition.Before, null);

        await handler.Handle(command, CancellationToken.None);

        var stored = await db.WorkflowTasks.FindAsync(task.Id);
        stored!.Status.Should().Be(TaskStatus.Delegated);

        var signerTasks = await db.WorkflowTasks
            .Where(t => t.AssigneeId == signer && t.Status == TaskStatus.Pending)
            .ToListAsync();
        signerTasks.Should().HaveCount(1);
    }

    [Fact]
    public async Task AddSigner_MissingTask_ThrowsNotFound()
    {
        await using var db = CreateDbContext();
        var handler = new AddSignerCommandHandler(db);
        var command = new AddSignerCommand(Guid.NewGuid(), Guid.NewGuid(), Guid.NewGuid(), SignPosition.Before, null);

        var act = async () => await handler.Handle(command, CancellationToken.None);

        var ex = await act.Should().ThrowAsync<NotFoundException>();
        ex.Which.Code.Should().Be(ErrorCode.NotFound);
    }

    [Fact]
    public async Task AddSigner_NonPendingTask_ThrowsInvalidState()
    {
        await using var db = CreateDbContext();
        var task = SeedTask(db, Guid.NewGuid(), TaskStatus.Approved);
        await db.SaveChangesAsync();

        var handler = new AddSignerCommandHandler(db);
        var command = new AddSignerCommand(task.Id, task.AssigneeId!.Value, Guid.NewGuid(), SignPosition.Before, null);

        var act = async () => await handler.Handle(command, CancellationToken.None);

        var ex = await act.Should().ThrowAsync<BusinessException>();
        ex.Which.Code.Should().Be(ErrorCode.InvalidState);
    }

    [Fact]
    public async Task AddSigner_NotCurrentHandler_ThrowsForbidden()
    {
        await using var db = CreateDbContext();
        var task = SeedTask(db, Guid.NewGuid(), TaskStatus.Pending);
        await db.SaveChangesAsync();

        var handler = new AddSignerCommandHandler(db);
        var command = new AddSignerCommand(task.Id, Guid.NewGuid(), Guid.NewGuid(), SignPosition.Before, null);

        var act = async () => await handler.Handle(command, CancellationToken.None);

        var ex = await act.Should().ThrowAsync<UnauthorizedException>();
        ex.Which.Code.Should().Be(ErrorCode.Forbidden);
    }

    [Fact]
    public async Task AddSigner_SelfSign_ThrowsBusiness()
    {
        await using var db = CreateDbContext();
        var current = Guid.NewGuid();
        var task = SeedTask(db, current, TaskStatus.Pending);
        await db.SaveChangesAsync();

        var handler = new AddSignerCommandHandler(db);
        var command = new AddSignerCommand(task.Id, current, current, SignPosition.Before, null);

        var act = async () => await handler.Handle(command, CancellationToken.None);

        var ex = await act.Should().ThrowAsync<BusinessException>();
        ex.Which.Code.Should().Be(ErrorCode.Business);
    }
}