Implement version check enhancements and add tests for December 2020 build

DorkNet.Server.Tests/VersionCheckControllerTests.cs

@@ -0,0 +1,56 @@
+using System.Text.Json;
+using DorkNet.Server.Compat;
+using DorkNet.Server.Controllers.Auth;
+using DorkNet.Server.Versions.Late2020;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Logging.Abstractions;
+
+namespace DorkNet.Server.Tests;
+
+public sealed class VersionCheckControllerTests
+{
+    [Fact]
+    public void December_2020_build_is_valid_with_minimal_service_config()
+    {
+        var controller = CreateController();
+
+        var result = Assert.IsType<OkObjectResult>(controller.Check("20201210", "0"));
+
+        Assert.Equal(0, ReadVersionStatus(result.Value));
+    }
+
+    [Fact]
+    public void Unknown_build_still_requires_update()
+    {
+        var controller = CreateController();
+
+        var result = Assert.IsType<OkObjectResult>(controller.Check("unknown", "0"));
+
+        Assert.Equal(2, ReadVersionStatus(result.Value));
+    }
+
+    private static VersionCheckController CreateController()
+    {
+        var config = new ConfigurationBuilder().Build();
+        var registry = new VersionRegistry(
+            [new Late2020VersionPlugin()],
+            new HashSet<string>(StringComparer.OrdinalIgnoreCase)
+            {
+                "december_2020_12_18",
+            },
+            "december_2020_12_18");
+
+        return new VersionCheckController(
+            config,
+            registry,
+            NullLogger<VersionCheckController>.Instance);
+    }
+
+    private static int ReadVersionStatus(object? value)
+    {
+        var json = JsonSerializer.Serialize(value);
+        using var document = JsonDocument.Parse(json);
+        return document.RootElement.GetProperty("VersionStatus").GetInt32();
+    }
+}