Update clients to use SecretApiKey authentication.

CoinbaseAdvancedTradeClient/CoinbaseAdvancedTradeClient.UnitTests/Authentication/SecretApiKeyAuthenticatorTests.cs

@@ -0,0 +1,47 @@
+using CoinbaseAdvancedTradeClient.Authentication;
+using CoinbaseAdvancedTradeClient.UnitTests.TestHelpers;
+using Xunit;
+
+namespace CoinbaseAdvancedTradeClient.UnitTests.Authentication
+{
+    public class SecretApiKeyAuthenticatorTests
+    {
+        [Fact]
+        public void GenerateBearerJWT_ValidParameters_ReturnsJWT()
+        {
+            // Arrange
+            var testKeySecret = TestConfigHelper.GenerateTestKeySecret();
+
+            // Act & Assert - Should not throw exception
+            var jwt = SecretApiKeyAuthenticator.GenerateBearerJWT(
+                "test-key-name",
+                testKeySecret,
+                "GET",
+                "api.coinbase.com",
+                "/v1/test"
+            );
+
+            // Basic JWT format validation
+            Assert.NotNull(jwt);
+            Assert.Contains(".", jwt);
+            var parts = jwt.Split('.');
+            Assert.Equal(3, parts.Length); // header.payload.signature
+        }
+
+        [Fact]
+        public void GenerateBearerJWT_InvalidKeySecret_ThrowsArgumentException()
+        {
+            // Act & Assert
+            Assert.Throws<ArgumentException>(() =>
+            {
+                SecretApiKeyAuthenticator.GenerateBearerJWT(
+                    "test-key-name",
+                    "invalid-key-format",
+                    "GET",
+                    "api.coinbase.com",
+                    "/v1/test"
+                );
+            });
+        }
+    }
+}

CoinbaseAdvancedTradeClient/CoinbaseAdvancedTradeClient.UnitTests/CoinbaseAdvancedTradeApiClientTests.cs

@@ -1,4 +1,5 @@
 using CoinbaseAdvancedTradeClient.Models.Config;
+using CoinbaseAdvancedTradeClient.UnitTests.TestHelpers;
 using Xunit;
 
 namespace CoinbaseAdvancedTradeClient.UnitTests
@@ -9,7 +10,7 @@ public class CoinbaseAdvancedTradeApiClientTests
         public void Constructor_NullConfig_ThrowsArgumentNullException()
         {
             //Arrange
-            ApiClientConfig config = null;
+            SecretApiKeyConfig config = null;
 
             //Act & Assert
             Assert.Throws<ArgumentNullException>(() => 
@@ -27,10 +28,10 @@ public void Constructor_NullConfig_ThrowsArgumentNullException()
         public void Constructor_EmptyConfigSetting_ThrowsArgumentException(string key, string secret)
         {
             //Arrange
-            ApiClientConfig config = new ApiClientConfig()
+            SecretApiKeyConfig config = new SecretApiKeyConfig()
             {
-                ApiKey = key,
-                ApiSecret = secret
+                KeyName = key,
+                KeySecret = string.IsNullOrWhiteSpace(secret) ? secret : TestConfigHelper.GenerateTestKeySecret()
             };
 
             //Act & Assert

CoinbaseAdvancedTradeClient/CoinbaseAdvancedTradeClient.UnitTests/CoinbaseAdvancedTradeClient.UnitTests.csproj

@@ -8,10 +8,10 @@
 
   <ItemGroup>
     <PackageReference Include="FakeItEasy" Version="8.3.0" />
-    <PackageReference Include="Flurl.Http" Version="3.2.4" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
-    <PackageReference Include="xunit" Version="2.4.2" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">
+    <PackageReference Include="Flurl.Http" Version="4.0.2" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>