[PM-22739] Add ClaimsPrincipal Extension

feat: add ClaimsPrincipal Extension
test: add tests

src/Core/Auth/UserFeatures/SendAccess/SendAccessClaimsPrincipalExtensions.cs

@@ -0,0 +1,22 @@
+using System.Security.Claims;
+using Bit.Core.Identity;
+
+namespace Bit.Core.Auth.UserFeatures.SendAccess;
+
+public static class SendAccessClaimsPrincipalExtensions
+{
+    public static Guid GetSendId(this ClaimsPrincipal user)
+    {
+        ArgumentNullException.ThrowIfNull(user);
+
+        var sendIdClaim = user.FindFirst(Claims.SendId)
+            ?? throw new InvalidOperationException("Send ID claim not found.");
+
+        if (!Guid.TryParse(sendIdClaim.Value, out var sendGuid))
+        {
+            throw new InvalidOperationException("Invalid Send ID claim value.");
+        }
+
+        return sendGuid;
+    }
+}

test/Core.Test/Auth/UserFeatures/SendAccess/SendAccessClaimsPrincipalExtensionsTests.cs

@@ -0,0 +1,54 @@
+using System.Security.Claims;
+using Bit.Core.Auth.UserFeatures.SendAccess;
+using Bit.Core.Identity;
+using Xunit;
+
+namespace Bit.Core.Test.Auth.UserFeatures.SendAccess;
+
+public class SendAccessClaimsPrincipalExtensionsTests
+{
+    [Fact]
+    public void GetSendId_ReturnsGuid_WhenClaimIsPresentAndValid()
+    {
+        // Arrange
+        var guid = Guid.NewGuid();
+        var claims = new[] { new Claim(Claims.SendId, guid.ToString()) };
+        var principal = new ClaimsPrincipal(new ClaimsIdentity(claims));
+
+        // Act
+        var result = principal.GetSendId();
+
+        // Assert
+        Assert.Equal(guid, result);
+    }
+
+    [Fact]
+    public void GetSendId_ThrowsInvalidOperationException_WhenClaimIsMissing()
+    {
+        // Arrange
+        var principal = new ClaimsPrincipal(new ClaimsIdentity());
+
+        // Act & Assert
+        var ex = Assert.Throws<InvalidOperationException>(() => principal.GetSendId());
+        Assert.Equal("Send ID claim not found.", ex.Message);
+    }
+
+    [Fact]
+    public void GetSendId_ThrowsInvalidOperationException_WhenClaimValueIsInvalid()
+    {
+        // Arrange
+        var claims = new[] { new Claim(Claims.SendId, "not-a-guid") };
+        var principal = new ClaimsPrincipal(new ClaimsIdentity(claims));
+
+        // Act & Assert
+        var ex = Assert.Throws<InvalidOperationException>(() => principal.GetSendId());
+        Assert.Equal("Invalid Send ID claim value.", ex.Message);
+    }
+
+    [Fact]
+    public void GetSendId_ThrowsArgumentNullException_WhenPrincipalIsNull()
+    {
+        // Act & Assert
+        Assert.Throws<ArgumentNullException>(() => SendAccessClaimsPrincipalExtensions.GetSendId(null));
+    }
+}