Add tests for ReCClient dependency injection setup

Added a new `DependencyInjectionTests` class to validate the
dependency injection setup for the `ReCClient` class.

- Added tests to ensure `ReCClient` can be resolved when registered
  with a base URL or custom HTTP client configuration.
- Verified default options are registered when no callback is
  supplied and that options callbacks are applied correctly.
- Added tests to validate behavior when `LogSuccessfulRequests`
  is enabled, including scenarios with and without a registered
  logger.
- Included necessary `using` directives for DI, logging, options,
  HTTP client, and the `ReC.Client` namespace.

tests/ReC.Tests/Client/DependencyInjectionTests.cs

@@ -0,0 +1,115 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using ReC.Client;
+using System.Net.Http;
+
+namespace ReC.Tests.Client;
+
+[TestFixture]
+public class DependencyInjectionTests
+{
+    [Test]
+    public void AddRecClient_with_base_url_registers_resolvable_client()
+    {
+        var services = new ServiceCollection();
+        services.AddLogging();
+        services.AddRecClient("https://example.invalid/");
+
+        using var provider = services.BuildServiceProvider();
+        using var scope = provider.CreateScope();
+
+        var client = scope.ServiceProvider.GetRequiredService<ReCClient>();
+
+        Assert.That(client, Is.Not.Null);
+        Assert.That(client.RecActions, Is.Not.Null);
+        Assert.That(client.Results, Is.Not.Null);
+        Assert.That(client.Profiles, Is.Not.Null);
+        Assert.That(client.EndpointAuth, Is.Not.Null);
+        Assert.That(client.EndpointParams, Is.Not.Null);
+        Assert.That(client.Endpoints, Is.Not.Null);
+        Assert.That(client.Common, Is.Not.Null);
+    }
+
+    [Test]
+    public void AddRecClient_with_configure_client_registers_resolvable_client()
+    {
+        var services = new ServiceCollection();
+        services.AddLogging();
+        services.AddRecClient(http =>
+        {
+            http.BaseAddress = new Uri("https://example.invalid/");
+            http.Timeout = TimeSpan.FromSeconds(5);
+        });
+
+        using var provider = services.BuildServiceProvider();
+        using var scope = provider.CreateScope();
+
+        var client = scope.ServiceProvider.GetRequiredService<ReCClient>();
+
+        Assert.That(client, Is.Not.Null);
+    }
+
+    [Test]
+    public void AddRecClient_registers_default_options_when_no_callback_supplied()
+    {
+        var services = new ServiceCollection();
+        services.AddLogging();
+        services.AddRecClient("https://example.invalid/");
+
+        using var provider = services.BuildServiceProvider();
+
+        var options = provider.GetRequiredService<IOptions<ReCClientOptions>>().Value;
+
+        Assert.That(options, Is.Not.Null);
+        Assert.That(options.LogSuccessfulRequests, Is.True, "Default value of LogSuccessfulRequests should be true.");
+    }
+
+    [Test]
+    public void AddRecClient_applies_options_callback()
+    {
+        var services = new ServiceCollection();
+        services.AddLogging();
+        services.AddRecClient("https://example.invalid/", opt => opt.LogSuccessfulRequests = true);
+
+        using var provider = services.BuildServiceProvider();
+
+        var options = provider.GetRequiredService<IOptions<ReCClientOptions>>().Value;
+
+        Assert.That(options.LogSuccessfulRequests, Is.True);
+    }
+
+    [Test]
+    public void ReCClient_constructor_throws_when_LogSuccessfulRequests_enabled_but_logger_is_null()
+    {
+        // Microsoft.Extensions.Http always registers an ILoggerFactory, so the
+        // "logger == null" branch can only be exercised by invoking the constructor directly.
+        var services = new ServiceCollection();
+        services.AddRecClient("https://example.invalid/", opt => opt.LogSuccessfulRequests = true);
+
+        using var provider = services.BuildServiceProvider();
+        var httpClientFactory = provider.GetRequiredService<IHttpClientFactory>();
+        var options = provider.GetRequiredService<IOptions<ReCClientOptions>>();
+
+        var ex = Assert.Throws<InvalidOperationException>(
+            () => new ReCClient(httpClientFactory, options, logger: null));
+
+        Assert.That(ex!.Message, Does.Contain(nameof(ReCClientOptions.LogSuccessfulRequests)));
+        Assert.That(ex.Message, Does.Contain("ILogger"));
+    }
+
+    [Test]
+    public void ReCClient_resolves_when_LogSuccessfulRequests_enabled_and_logger_registered()
+    {
+        var services = new ServiceCollection();
+        services.AddLogging();
+        services.AddRecClient("https://example.invalid/", opt => opt.LogSuccessfulRequests = true);
+
+        using var provider = services.BuildServiceProvider();
+        using var scope = provider.CreateScope();
+
+        var client = scope.ServiceProvider.GetRequiredService<ReCClient>();
+
+        Assert.That(client, Is.Not.Null);
+    }
+}