Refactor RepeatingTaskHandler (#796)

* Refactor RepeatingTaskHandler into an ASP.NET service

* Add unit tests for RepeatingTaskService

* Make repeating task unit tests work independent of time

* Fix weird behavior when task is canceled

ProjectLighthouse.Tests/Unit/RepeatingTaskTests.cs

@@ -0,0 +1,120 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using LBPUnion.ProjectLighthouse.Database;
+using LBPUnion.ProjectLighthouse.Services;
+using LBPUnion.ProjectLighthouse.Types.Maintenance;
+using Microsoft.Extensions.DependencyInjection;
+using Moq;
+using Xunit;
+
+namespace LBPUnion.ProjectLighthouse.Tests.Unit;
+
+[Trait("Category", "Unit")]
+public class RepeatingTaskTests
+{
+    private class TestTask : IRepeatingTask
+    {
+        public string Name { get; init; } = "";
+        public TimeSpan RepeatInterval => TimeSpan.FromSeconds(5);
+        public DateTime LastRan { get; set; }
+        public Task Run(DatabaseContext database) => Task.CompletedTask;
+    }
+
+    [Fact]
+    public void GetNextTask_ShouldReturnNull_WhenTaskListEmpty()
+    {
+        List<IRepeatingTask> tasks = new();
+        IServiceProvider provider = new DefaultServiceProviderFactory().CreateServiceProvider(new ServiceCollection());
+        RepeatingTaskService service = new(provider, tasks);
+
+        bool gotTask = service.TryGetNextTask(out IRepeatingTask? outTask);
+        Assert.False(gotTask);
+        Assert.Null(outTask);
+    }
+
+    [Fact]
+    public void GetNextTask_ShouldReturnTask_WhenTaskListContainsOne()
+    {
+        List<IRepeatingTask> tasks = new()
+        {
+            new TestTask(),
+        };
+        IServiceProvider provider = new DefaultServiceProviderFactory().CreateServiceProvider(new ServiceCollection());
+        RepeatingTaskService service = new(provider, tasks);
+
+        bool gotTask = service.TryGetNextTask(out IRepeatingTask? outTask);
+        Assert.True(gotTask);
+        Assert.NotNull(outTask);
+    }
+
+    [Fact]
+    public void GetNextTask_ShouldReturnShortestTask_WhenTaskListContainsMultiple()
+    {
+        List<IRepeatingTask> tasks = new()
+        {
+            new TestTask
+            {
+                Name = "Task 1",
+                LastRan = DateTime.UtcNow,
+            },
+            new TestTask
+            {
+                Name = "Task 2",
+                LastRan = DateTime.UtcNow.AddMinutes(1),
+            },
+            new TestTask
+            {
+                Name = "Task 3",
+                LastRan = DateTime.UtcNow.AddMinutes(-1),
+            },
+        };
+        IServiceProvider provider = new DefaultServiceProviderFactory().CreateServiceProvider(new ServiceCollection());
+        RepeatingTaskService service = new(provider, tasks);
+
+        bool gotTask = service.TryGetNextTask(out IRepeatingTask? outTask);
+        Assert.True(gotTask);
+        Assert.NotNull(outTask);
+        Assert.Equal("Task 3", outTask.Name);
+    }
+
+    [Fact]
+    public async Task BackgroundService_ShouldExecuteTask_AndUpdateTime()
+    {
+        Mock<IRepeatingTask> taskMock = new();
+        taskMock.Setup(t => t.Run(It.IsAny<DatabaseContext>())).Returns(Task.CompletedTask);
+        taskMock.SetupGet(t => t.RepeatInterval).Returns(TimeSpan.FromSeconds(10));
+        TaskCompletionSource taskCompletion = new();
+        DateTime lastRan = default;
+        taskMock.SetupSet(t => t.LastRan = It.IsAny<DateTime>())
+            .Callback<DateTime>(time =>
+            {
+                lastRan = time;
+                taskCompletion.TrySetResult();
+            });
+        taskMock.SetupGet(t => t.LastRan).Returns(() => lastRan);
+        List<IRepeatingTask> tasks = new()
+        {
+            taskMock.Object,
+        };
+        ServiceCollection serviceCollection = new();
+        serviceCollection.AddScoped(_ => new Mock<DatabaseContext>().Object);
+        IServiceProvider provider = new DefaultServiceProviderFactory().CreateServiceProvider(serviceCollection);
+
+        RepeatingTaskService service = new(provider, tasks);
+
+        CancellationTokenSource stoppingToken = new();
+
+        await service.StartAsync(stoppingToken.Token);
+
+        await taskCompletion.Task;
+        stoppingToken.Cancel();
+
+        Assert.NotNull(service.ExecuteTask);
+        await service.ExecuteTask;
+
+        taskMock.Verify(x => x.Run(It.IsAny<DatabaseContext>()), Times.Once);
+        taskMock.VerifySet(x => x.LastRan = It.IsAny<DateTime>(), Times.Once());
+    }
+}