Add a basic application test

tests/Tgstation.Server.Host.Tests/Core/TestApplication.cs

@@ -0,0 +1,35 @@
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Logging;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Moq;
+using System;
+
+namespace Tgstation.Server.Host.Core.Tests
+{
+	[TestClass]
+	public sealed class TestApplication
+	{
+		[TestMethod]
+		public void TestMethodThrows()
+		{
+			Assert.ThrowsException<ArgumentNullException>(() => new Application(null, null));
+			var mockConfiguration = new Mock<IConfiguration>();
+			Assert.ThrowsException<ArgumentNullException>(() => new Application(mockConfiguration.Object, null));
+
+			var mockHostingEnvironment = new Mock<IHostingEnvironment>();
+
+			var app = new Application(mockConfiguration.Object, mockHostingEnvironment.Object);
+
+			Assert.ThrowsException<ArgumentNullException>(() => app.ConfigureServices(null));
+			Assert.ThrowsException<ArgumentNullException>(() => app.Configure(null, null, null));
+
+			var mockAppBuilder = new Mock<IApplicationBuilder>();
+			Assert.ThrowsException<ArgumentNullException>(() => app.Configure(mockAppBuilder.Object, null, null));
+
+			var mockLogger = new Mock<ILogger<Application>>();
+			Assert.ThrowsException<ArgumentNullException>(() => app.Configure(mockAppBuilder.Object, mockLogger.Object, null));
+		}
+	}
+}