Add backend test harness with mock SQLite

GameList.Tests/VoteTests.cs

@@ -0,0 +1,61 @@
+using System.Net;
+using System.Net;
+using System.Net.Http.Json;
+using GameList.Tests.Support;
+
+namespace GameList.Tests;
+
+public class VoteTests
+{
+    [Fact]
+    public async Task Finalizing_votes_blocks_further_changes()
+    {
+        using var factory = new TestWebApplicationFactory();
+        var client = factory.CreateClientWithCookies();
+        await client.RegisterAsync("voter");
+
+        var suggestionId = await client.CreateSuggestionAsync("VoteGame");
+
+        await client.PostAsJsonAsync("/api/me/phase/next", new { });
+
+        var vote = await client.PostAsJsonAsync("/api/votes", new { SuggestionId = suggestionId, Score = 7 });
+        vote.EnsureSuccessStatusCode();
+
+        var finalize = await client.PostAsJsonAsync("/api/votes/finalize", new { Final = true });
+        finalize.EnsureSuccessStatusCode();
+
+        var change = await client.PostAsJsonAsync("/api/votes", new { SuggestionId = suggestionId, Score = 5 });
+
+        Assert.Equal(HttpStatusCode.BadRequest, change.StatusCode);
+    }
+
+    [Fact]
+    public async Task Linked_votes_apply_to_all_linked_suggestions()
+    {
+        using var factory = new TestWebApplicationFactory();
+        var admin = factory.CreateClientWithCookies();
+        await admin.RegisterAsync("admin", admin: true);
+        await admin.PostAsJsonAsync("/api/me/phase/next", new { });
+
+        var player = factory.CreateClientWithCookies();
+        await player.RegisterAsync("linker");
+
+        var id1 = await player.CreateSuggestionAsync("Game A");
+        var id2 = await player.CreateSuggestionAsync("Game B");
+
+        await player.PostAsJsonAsync("/api/me/phase/next", new { });
+
+        var linkResponse = await admin.PostAsJsonAsync("/api/admin/link-suggestions", new { SourceSuggestionId = id1, TargetSuggestionId = id2 });
+        linkResponse.EnsureSuccessStatusCode();
+
+        var vote = await player.PostAsJsonAsync("/api/votes", new { SuggestionId = id1, Score = 9 });
+        vote.EnsureSuccessStatusCode();
+
+        var mine = await player.GetFromJsonAsync<List<VoteRecord>>("/api/votes/mine");
+
+        Assert.Equal(2, mine.Count);
+        Assert.All(mine, v => Assert.Equal(9, v.Score));
+    }
+
+    private record VoteRecord(int SuggestionId, int Score);
+}