Implementation for SEP-2243 Http Standardization (#1553)

Co-authored-by: Tarek Mahmoud Sayed <tarekms@microsoft.com>
Co-authored-by: Tarek Mahmoud Sayed <tarekms@ntdev.microsoft.com>
Co-authored-by: Tarek Mahmoud Sayed <10833894+tarekgh@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tests/ModelContextProtocol.Tests/Server/McpHeaderAttributeTests.cs

@@ -0,0 +1,59 @@
+using ModelContextProtocol.Server;
+
+namespace ModelContextProtocol.Tests.Server;
+
+public class McpHeaderAttributeTests
+{
+    [Theory]
+    [InlineData("Region")]
+    [InlineData("TenantId")]
+    [InlineData("Priority")]
+    [InlineData("X-Custom")]
+    public void Constructor_ValidHeaderName_Succeeds(string name)
+    {
+        var attr = new McpHeaderAttribute(name);
+        Assert.Equal(name, attr.Name);
+    }
+
+    [Fact]
+    public void Constructor_NameWithSpace_Throws()
+    {
+        Assert.Throws<ArgumentException>(() => new McpHeaderAttribute("My Region"));
+    }
+
+    [Fact]
+    public void Constructor_NameWithColon_Throws()
+    {
+        Assert.Throws<ArgumentException>(() => new McpHeaderAttribute("Region:Primary"));
+    }
+
+    [Fact]
+    public void Constructor_NullName_Throws()
+    {
+        Assert.ThrowsAny<ArgumentException>(() => new McpHeaderAttribute(null!));
+    }
+
+    [Fact]
+    public void Constructor_EmptyName_Throws()
+    {
+        Assert.ThrowsAny<ArgumentException>(() => new McpHeaderAttribute(""));
+    }
+
+    [Fact]
+    public void Constructor_WhitespaceName_Throws()
+    {
+        Assert.ThrowsAny<ArgumentException>(() => new McpHeaderAttribute("  "));
+    }
+
+    [Fact]
+    public void Constructor_NameWithControlCharacter_Throws()
+    {
+        Assert.Throws<ArgumentException>(() => new McpHeaderAttribute("Region\t1"));
+    }
+
+    [Fact]
+    public void Constructor_NameWithNonAscii_Throws()
+    {
+        Assert.Throws<ArgumentException>(() => new McpHeaderAttribute("Région"));
+    }
+}