feat: add rest client to get gateway url

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

@@ -0,0 +1,73 @@
+using System.Net;
+
+using Microsoft.Extensions.Logging;
+
+using Moq;
+
+using RichardSzalay.MockHttp;
+
+namespace StevesBot.Worker.Tests.Unit;
+
+public sealed class DiscordRestClientTests : IDisposable
+{
+  private const string BaseUrl = "https://discord.com/api/v10";
+  private static string GatewayUrl => $"{BaseUrl}/gateway";
+
+  private readonly Mock<ILogger<DiscordRestClient>> _loggerMock = new();
+  private readonly MockHttpMessageHandler _mockHttpMessageHandler;
+  private readonly DiscordRestClient _discordRestClient;
+
+  public DiscordRestClientTests()
+  {
+    _mockHttpMessageHandler = new MockHttpMessageHandler();
+    var httpClient = _mockHttpMessageHandler.ToHttpClient();
+    httpClient.BaseAddress = new Uri("https://discord.com/api/v10/");
+    _discordRestClient = new DiscordRestClient(_loggerMock.Object, httpClient);
+  }
+
+  [Fact]
+  public async Task GetGatewayUrlAsync_WhenRequestFails_ItShouldThrowException()
+  {
+    _mockHttpMessageHandler
+      .When(GatewayUrl)
+      .Respond(HttpStatusCode.InternalServerError);
+
+    var act = async () => await _discordRestClient.GetGatewayUrlAsync(CancellationToken.None);
+
+    await act.Should().ThrowAsync<DiscordRestClientException>();
+  }
+
+  [Fact]
+  public async Task GetGatewayUrlAsync_WhenResponseIsNull_ItShouldThrowException()
+  {
+    _mockHttpMessageHandler
+      .When(GatewayUrl)
+      .Respond(HttpStatusCode.OK, "application/json", "null");
+
+    var act = async () => await _discordRestClient.GetGatewayUrlAsync(CancellationToken.None);
+
+    await act.Should().ThrowAsync<DiscordRestClientException>();
+  }
+
+  [Fact]
+  public async Task GetGatewayUrlAsync_WhenRequestIsSuccessful_ItShouldReturnGatewayUrl()
+  {
+    var expectedUrl = "test";
+    var jsonResponse = $@"{{ 
+      ""url"": ""{expectedUrl}"" 
+    }}";
+
+    _mockHttpMessageHandler
+      .When(GatewayUrl)
+      .Respond(HttpStatusCode.OK, "application/json", jsonResponse);
+
+    var result = await _discordRestClient.GetGatewayUrlAsync(CancellationToken.None);
+
+    result.Should().Be(expectedUrl);
+  }
+
+  public void Dispose()
+  {
+    _mockHttpMessageHandler.Dispose();
+  }
+}