Added Client and Network unit tests

Author: skuill

Tests/LyricsScraperNET.UnitTest/LyricsScraperClientTests.cs

@@ -304,6 +304,34 @@ public void AddAndRemoveExternalProvider_ShouldBeSwitched()
             Assert.Null(lyricsScraperClient[externalProviderType]);
         }
 
+        [Theory]
+        [InlineData(ExternalProviderType.AZLyrics)]
+        [InlineData(ExternalProviderType.None)]
+        public void RemoveProvider_NotExisted_ShouldNotThrowException(ExternalProviderType externalProviderType)
+        {
+            // Arrange
+            var lyricsScraperClient = new LyricsScraperClient();
+
+            // Assert 0
+            Assert.Null(lyricsScraperClient[externalProviderType]);
+
+            // Act
+            var exception = Record.Exception(() => lyricsScraperClient.RemoveProvider(externalProviderType));
+
+            // Assert 1
+            Assert.Null(exception);
+        }
+
+        [Fact]
+        public void AddProvider_NullProvider_ShouldThrowException()
+        {
+            // Arrange
+            var lyricsScraperClient = new LyricsScraperClient();
+
+            // Act & Assert
+            Assert.Throws<ArgumentNullException>(() => lyricsScraperClient.AddProvider(null));
+        }
+
         [Fact]
         public void SearchLyric_Should_Throw_OperationCanceledException_When_Cancellation_Is_Requested()
         {

Tests/LyricsScraperNET.UnitTest/Network/HtmlAgilityWebClientTests.cs

@@ -0,0 +1,39 @@
+using LyricsScraperNET.Network;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace LyricsScraperNET.UnitTest.Network
+{
+    public class HtmlAgilityWebClientTests
+    {
+        [Fact]
+        public void Load_InvalidUri_ShouldReturnEmptyString()
+        {
+            // Arrange
+            var webClient = new HtmlAgilityWebClient();
+            var invalidUri = new Uri("http://nonexistent12345123.url");
+
+            // Act
+            var result = webClient.Load(invalidUri, CancellationToken.None);
+
+            // Assert
+            Assert.Equal(string.Empty, result);
+        }
+
+        [Fact]
+        public async Task LoadAsync_InvalidUri_ShouldReturnEmptyString()
+        {
+            // Arrange
+            var webClient = new HtmlAgilityWebClient();
+            var invalidUri = new Uri("http://nonexistent12345123.url");
+
+            // Act
+            var result = await webClient.LoadAsync(invalidUri, CancellationToken.None);
+
+            // Assert
+            Assert.Equal(string.Empty, result);
+        }
+    }
+}

Tests/LyricsScraperNET.UnitTest/Network/NetHttpClientTests.cs

@@ -0,0 +1,71 @@
+using LyricsScraperNET.Network;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace LyricsScraperNET.UnitTest.Network
+{
+    public class NetHttpClientTests
+    {
+        [Fact]
+        public void Load_InvalidUri_ShouldReturnEmptyString()
+        {
+            // Arrange
+            var webClient = new NetHttpClient();
+            var invalidUri = new Uri("http://nonexistent12345123.url");
+
+            // Act
+            var result = webClient.Load(invalidUri, CancellationToken.None);
+
+            // Assert
+            Assert.Equal(string.Empty, result);
+        }
+
+        [Fact]
+        public void Load_CancelledToken_ShouldThrowException()
+        {
+            // Arrange
+            var webClient = new NetHttpClient();
+            var invalidUri = new Uri("http://nonexistent12345123.url");
+            var token = GetCancelledCancellationToken();
+
+            // Act & Assert
+            Assert.Throws<TaskCanceledException>(() => webClient.Load(invalidUri, token));
+        }
+
+        [Fact]
+        public async Task LoadAsync_InvalidUri_ShouldReturnEmptyString()
+        {
+            // Arrange
+            var webClient = new NetHttpClient();
+            var invalidUri = new Uri("http://nonexistent12345123.url");
+
+            // Act
+            var result = await webClient.LoadAsync(invalidUri, CancellationToken.None);
+
+            // Assert
+            Assert.Equal(string.Empty, result);
+        }
+
+        [Fact]
+        public async Task LoadAsync_CancelledToken_ShouldThrowException()
+        {
+            // Arrange
+            var webClient = new NetHttpClient();
+            var invalidUri = new Uri("http://nonexistent12345123.url");
+            var token = GetCancelledCancellationToken();
+
+            // Act & Assert
+            await Assert.ThrowsAsync<TaskCanceledException>(async () => await webClient.LoadAsync(invalidUri, token));
+        }
+
+        private CancellationToken GetCancelledCancellationToken()
+        {
+            CancellationTokenSource source = new CancellationTokenSource();
+            CancellationToken token = source.Token;
+            source.Cancel();
+            return token;
+        }
+    }
+}