tests: add converter tests

src/StevesBot.Worker.Tests/Unit/DiscordEventConverterTests.cs

@@ -0,0 +1,54 @@
+namespace StevesBot.Worker.Tests.Unit;
+
+public class DiscordEventConverterTests
+{
+  private readonly JsonSerializerOptions _options = new()
+  {
+    Converters =
+    {
+      new DiscordEventConverter()
+    }
+  };
+  private readonly Type _discordEventType = typeof(DiscordEvent);
+  private readonly DiscordEventConverter _converter = new();
+
+  [Fact]
+  public void Read_WhenCalledWithUnknownOpCode_ItShouldReturnDiscordEvent()
+  {
+    var data = new
+    {
+      op = 99,
+      s = null as int?,
+      t = null as string,
+      d = null as object
+    };
+
+    var result = Read(data);
+
+    result.Should().BeOfType<DiscordEvent>();
+  }
+
+  [Fact]
+  public void Read_WhenCalledWithDispatchOpCodeAndNoType_ItShouldReturnDispatchEvent()
+  {
+    var data = new
+    {
+      op = DiscordOpCodes.Dispatch,
+      s = null as int?,
+      t = null as string,
+      d = null as object
+    };
+
+    var result = Read(data);
+
+    result.Should().BeOfType<DiscordEvent>();
+  }
+
+  private DiscordEvent? Read(object data)
+  {
+    var json = JsonSerializer.Serialize(data);
+    var utf8Json = Encoding.UTF8.GetBytes(json);
+    var reader = new Utf8JsonReader(utf8Json);
+    return _converter.Read(ref reader, _discordEventType, _options);
+  }
+}