Add backend test harness with mock SQLite

GameList.Tests/StateTests.cs

@@ -0,0 +1,45 @@
+using System.Net;
+using System.Net;
+using System.Net.Http.Json;
+using System.Text.Json;
+using GameList.Domain;
+using GameList.Tests.Support;
+
+namespace GameList.Tests;
+
+public class StateTests
+{
+    [Fact]
+    public async Task Cannot_advance_to_results_when_locked()
+    {
+        using var factory = new TestWebApplicationFactory();
+        var client = factory.CreateClientWithCookies();
+        await client.RegisterAsync("player");
+
+        var toVote = await client.PostAsync("/api/me/phase/next", JsonContent.Create(new { }));
+        toVote.EnsureSuccessStatusCode();
+
+        var toResults = await client.PostAsync("/api/me/phase/next", JsonContent.Create(new { }));
+
+        Assert.Equal(HttpStatusCode.BadRequest, toResults.StatusCode);
+    }
+
+    [Fact]
+    public async Task Admin_opening_results_moves_players_to_results_phase()
+    {
+        using var factory = new TestWebApplicationFactory();
+        var admin = factory.CreateClientWithCookies();
+        await admin.RegisterAsync("admin", admin: true);
+
+        var player = factory.CreateClientWithCookies();
+        await player.RegisterAsync("user");
+
+        var toggle = await admin.PostAsJsonAsync("/api/admin/results", new { resultsOpen = true });
+        toggle.EnsureSuccessStatusCode();
+
+        var state = await player.GetFromJsonAsync<JsonElement>("/api/state");
+
+        Assert.Equal((int)Phase.Results, state.GetProperty("CurrentPhase").GetInt32());
+        Assert.True(state.GetProperty("resultsOpen").GetBoolean());
+    }
+}