diff --git a/Jenkinsfile b/Jenkinsfile
deleted file mode 100644
index 6ed9b0c..0000000
--- a/Jenkinsfile
+++ /dev/null
@@ -1,21 +0,0 @@
-pipeline {
-    agent {
-        label '.net7.0'
-    }
-    stages {
-        stage('Build classlib') {
-            steps {
-                sh '''cd classlib
-                dotnet build --no-incremental --force --configuration Release
-                dotnet publish -c Release'''
-                
-                contentReplace(configs: [fileContentReplaceConfig(configs: [fileContentReplaceItemConfig(replace: 'ModuleVersion = \'2.0.$BUILD_NUMBER\'', search: 'ModuleVersion = \'2.0\'')], fileEncoding: 'UTF-8', filePath: 'ps.ipam.psd1')])
-            }
-        }
-    }
-    post {
-        success {
-            archiveArtifacts artifacts: 'classlib/bin/Release/netstandard2.1/publish/*.dll, *.psd1, *.psm1, LICENSE, **/*.ps1xml, **/*.ps1', followSymlinks: false, onlyIfSuccessful: true
-        }
-    }
-}
\ No newline at end of file
diff --git a/classlib.tests/Mocks/CmdletTestHelper.cs b/classlib.tests/Mocks/CmdletTestHelper.cs
new file mode 100644
index 0000000..f1c061b
--- /dev/null
+++ b/classlib.tests/Mocks/CmdletTestHelper.cs
@@ -0,0 +1,139 @@
+namespace PS.IPAM.Tests.Mocks;
+
+using System.Management.Automation;
+using System.Management.Automation.Host;
+using System.Reflection;
+
+/// <summary>
+/// Helper class for testing PowerShell cmdlets.
+/// </summary>
+public class CmdletTestHelper<T> : IDisposable where T : PSCmdlet, new()
+{
+    private readonly T _cmdlet;
+    private readonly List<object> _output = new();
+    private readonly List<ErrorRecord> _errors = new();
+    private bool _disposed;
+
+    public CmdletTestHelper()
+    {
+        _cmdlet = new T();
+    }
+
+    /// <summary>
+    /// Gets the cmdlet instance for setting parameters.
+    /// </summary>
+    public T Cmdlet => _cmdlet;
+
+    /// <summary>
+    /// Gets the output objects written by the cmdlet.
+    /// </summary>
+    public IReadOnlyList<object> Output => _output.AsReadOnly();
+
+    /// <summary>
+    /// Gets the errors written by the cmdlet.
+    /// </summary>
+    public IReadOnlyList<ErrorRecord> Errors => _errors.AsReadOnly();
+
+    /// <summary>
+    /// Gets whether any errors were written.
+    /// </summary>
+    public bool HasErrors => _errors.Count > 0;
+
+    /// <summary>
+    /// Invokes the cmdlet and captures output.
+    /// </summary>
+    public void Invoke()
+    {
+        // Use reflection to call the protected ProcessRecord method
+        var processMethod = typeof(T).GetMethod("ProcessRecord",
+            BindingFlags.NonPublic | BindingFlags.Instance);
+
+        if (processMethod == null)
+        {
+            throw new InvalidOperationException("ProcessRecord method not found on cmdlet.");
+        }
+
+        // Set up a mock command runtime to capture output
+        var runtime = new MockCommandRuntime(_output, _errors);
+        var runtimeProperty = typeof(Cmdlet).GetProperty("CommandRuntime",
+            BindingFlags.Public | BindingFlags.Instance);
+
+        runtimeProperty?.SetValue(_cmdlet, runtime);
+
+        // Invoke the method
+        try
+        {
+            processMethod.Invoke(_cmdlet, null);
+        }
+        catch (TargetInvocationException ex) when (ex.InnerException != null)
+        {
+            // Unwrap the exception
+            throw ex.InnerException;
+        }
+    }
+
+    public void Dispose()
+    {
+        if (!_disposed)
+        {
+            _disposed = true;
+        }
+    }
+}
+
+/// <summary>
+/// Mock implementation of ICommandRuntime for capturing cmdlet output.
+/// This is a minimal implementation that only handles the methods we need for testing.
+/// </summary>
+internal class MockCommandRuntime : ICommandRuntime
+{
+    private readonly List<object> _output;
+    private readonly List<ErrorRecord> _errors;
+
+    public MockCommandRuntime(List<object> output, List<ErrorRecord> errors)
+    {
+        _output = output;
+        _errors = errors;
+    }
+
+    public PSHost Host => null!;
+    public PSTransactionContext CurrentPSTransaction => null!;
+
+    public bool ShouldContinue(string query, string caption) => true;
+    public bool ShouldContinue(string query, string caption, ref bool yesToAll, ref bool noToAll) => true;
+    public bool ShouldProcess(string target) => true;
+    public bool ShouldProcess(string target, string action) => true;
+    public bool ShouldProcess(string verboseDescription, string verboseWarning, string caption) => true;
+    public bool ShouldProcess(string verboseDescription, string verboseWarning, string caption, out ShouldProcessReason shouldProcessReason)
+    {
+        shouldProcessReason = ShouldProcessReason.None;
+        return true;
+    }
+
+    public bool TransactionAvailable() => false;
+
+    public void ThrowTerminatingError(ErrorRecord errorRecord) => throw errorRecord.Exception;
+
+    public void WriteCommandDetail(string text) { }
+    public void WriteDebug(string text) { }
+    public void WriteError(ErrorRecord errorRecord) => _errors.Add(errorRecord);
+    public void WriteObject(object sendToPipeline) => _output.Add(sendToPipeline);
+    public void WriteObject(object sendToPipeline, bool enumerateCollection)
+    {
+        if (enumerateCollection && sendToPipeline is System.Collections.IEnumerable enumerable)
+        {
+            foreach (var item in enumerable)
+            {
+                _output.Add(item);
+            }
+        }
+        else
+        {
+            _output.Add(sendToPipeline);
+        }
+    }
+    public void WriteProgress(ProgressRecord progressRecord) { }
+    public void WriteProgress(long sourceId, ProgressRecord progressRecord) { }
+    public void WriteVerbose(string text) { }
+    public void WriteWarning(string text) { }
+}
diff --git a/classlib.tests/Mocks/MockHttpMessageHandler.cs b/classlib.tests/Mocks/MockHttpMessageHandler.cs
new file mode 100644
index 0000000..497a788
--- /dev/null
+++ b/classlib.tests/Mocks/MockHttpMessageHandler.cs
@@ -0,0 +1,172 @@
+namespace PS.IPAM.Tests.Mocks;
+
+using System.Net;
+
+/// <summary>
+/// A mock HTTP message handler for testing HTTP requests without making actual network calls.
+/// This handler does not dispose itself when the HttpClient is disposed, allowing reuse in tests.
+/// </summary>
+public class MockHttpMessageHandler : HttpMessageHandler
+{
+    private readonly Queue<MockResponse> _responses = new();
+    private readonly List<HttpRequestMessage> _requests = new();
+    private bool _disposed = false;
+
+    /// <summary>
+    /// Gets all requests that were sent through this handler.
+    /// </summary>
+    public IReadOnlyList<HttpRequestMessage> Requests => _requests.AsReadOnly();
+
+    /// <summary>
+    /// Gets the last request that was sent through this handler.
+    /// </summary>
+    public HttpRequestMessage? LastRequest => _requests.LastOrDefault();
+
+    /// <summary>
+    /// Queues a response to be returned for the next request.
+    /// </summary>
+    public MockHttpMessageHandler WithResponse(HttpStatusCode statusCode, string content, string contentType = "application/json")
+    {
+        _responses.Enqueue(new MockResponse(statusCode, content, contentType));
+        return this;
+    }
+
+    /// <summary>
+    /// Queues a successful JSON response.
+    /// </summary>
+    public MockHttpMessageHandler WithJsonResponse(string jsonContent)
+    {
+        return WithResponse(HttpStatusCode.OK, jsonContent, "application/json");
+    }
+
+    /// <summary>
+    /// Queues a successful response with phpIPAM-style wrapper.
+    /// </summary>
+    public MockHttpMessageHandler WithSuccessResponse(string dataJson)
+    {
+        var response = $"{{\"code\":200,\"success\":true,\"data\":{dataJson}}}";
+        return WithJsonResponse(response);
+    }
+
+    /// <summary>
+    /// Queues a 404 Not Found response.
+    /// </summary>
+    public MockHttpMessageHandler WithNotFoundResponse()
+    {
+        return WithResponse(HttpStatusCode.NotFound, "{\"code\":404,\"success\":false,\"message\":\"Not found\"}", "application/json");
+    }
+
+    /// <summary>
+    /// Queues an error response.
+    /// </summary>
+    public MockHttpMessageHandler WithErrorResponse(HttpStatusCode statusCode, string message)
+    {
+        var response = $"{{\"code\":{(int)statusCode},\"success\":false,\"message\":\"{message}\"}}";
+        return WithResponse(statusCode, response, "application/json");
+    }
+
+    /// <summary>
+    /// Queues an exception to be thrown on the next request.
+    /// </summary>
+    public MockHttpMessageHandler WithException(Exception exception)
+    {
+        _responses.Enqueue(new MockResponse(exception));
+        return this;
+    }
+
+    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+    {
+        if (_disposed)
+        {
+            throw new ObjectDisposedException(nameof(MockHttpMessageHandler));
+        }
+
+        _requests.Add(request);
+
+        if (_responses.Count == 0)
+        {
+            throw new InvalidOperationException("No mock response configured. Call WithResponse() before making requests.");
+        }
+
+        var mockResponse = _responses.Dequeue();
+
+        if (mockResponse.Exception != null)
+        {
+            throw mockResponse.Exception;
+        }
+
+        var response = new HttpResponseMessage(mockResponse.StatusCode)
+        {
+            Content = new StringContent(mockResponse.Content, System.Text.Encoding.UTF8, mockResponse.ContentType),
+            RequestMessage = request
+        };
+
+        return Task.FromResult(response);
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        // Don't actually dispose - allow reuse in tests
+        // The test itself is responsible for cleanup
+    }
+
+    /// <summary>
+    /// Actually disposes the handler. Call this in test cleanup.
+    /// </summary>
+    public void ForceDispose()
+    {
+        _disposed = true;
+        base.Dispose(true);
+    }
+
+    /// <summary>
+    /// Verifies that a request was made to the expected URL.
+    /// </summary>
+    public bool WasRequestMadeTo(string urlContains)
+    {
+        return _requests.Any(r => r.RequestUri?.ToString().Contains(urlContains) == true);
+    }
+
+    /// <summary>
+    /// Verifies that a request with the expected method was made.
+    /// </summary>
+    public bool WasRequestMadeWithMethod(HttpMethod method)
+    {
+        return _requests.Any(r => r.Method == method);
+    }
+
+    /// <summary>
+    /// Gets the value of a header from the last request.
+    /// </summary>
+    public string? GetLastRequestHeader(string headerName)
+    {
+        if (LastRequest?.Headers.TryGetValues(headerName, out var values) == true)
+        {
+            return values.FirstOrDefault();
+        }
+        return null;
+    }
+
+    private class MockResponse
+    {
+        public HttpStatusCode StatusCode { get; }
+        public string Content { get; }
+        public string ContentType { get; }
+        public Exception? Exception { get; }
+
+        public MockResponse(HttpStatusCode statusCode, string content, string contentType)
+        {
+            StatusCode = statusCode;
+            Content = content;
+            ContentType = contentType;
+        }
+
+        public MockResponse(Exception exception)
+        {
+            Exception = exception;
+            StatusCode = HttpStatusCode.InternalServerError;
+            Content = string.Empty;
+            ContentType = string.Empty;
+        }
+    }
+}
diff --git a/classlib.tests/Models/AddressTests.cs b/classlib.tests/Models/AddressTests.cs
new file mode 100644
index 0000000..60ec426
--- /dev/null
+++ b/classlib.tests/Models/AddressTests.cs
@@ -0,0 +1,116 @@
+namespace PS.IPAM.Tests.Models;
+
+using FluentAssertions;
+using PS.IPAM;
+using Xunit;
+
+public class AddressTests
+{
+    [Fact]
+    public void Constructor_SetsAllProperties()
+    {
+        // Arrange
+        var id = 1;
+        var subnetId = 10;
+        var ip = "192.168.1.100";
+        var isGateway = true;
+        var description = "Test server";
+        var hostname = "server01.example.com";
+        var mac = "00:11:22:33:44:55";
+        var owner = "admin";
+        var tagId = 2;
+        var deviceId = 5;
+        var location = "DC1";
+        var port = "eth0";
+        var note = "Production server";
+        var lastSeen = new DateTime(2026, 1, 15, 10, 30, 0);
+        var excludePing = false;
+        var ptrIgnore = true;
+        var ptr = 1;
+        var firewallObject = "FW_SERVER01";
+        var editDate = new DateTime(2026, 1, 10, 8, 0, 0);
+        var customerId = 100;
+        var extendedData = new Dictionary<string, object> { { "custom_field1", "value1" } };
+
+        // Act
+        var address = new Address(
+            id, subnetId, ip, isGateway, description, hostname, mac, owner,
+            tagId, deviceId, location, port, note, lastSeen, excludePing,
+            ptrIgnore, ptr, firewallObject, editDate, customerId, extendedData
+        );
+
+        // Assert
+        address.Id.Should().Be(id);
+        address.SubnetId.Should().Be(subnetId);
+        address.Ip.Should().Be(ip);
+        address.IsGateway.Should().Be(isGateway);
+        address.Description.Should().Be(description);
+        address.Hostname.Should().Be(hostname);
+        address.MAC.Should().Be(mac);
+        address.Owner.Should().Be(owner);
+        address.TagId.Should().Be(tagId);
+        address.DeviceId.Should().Be(deviceId);
+        address.Location.Should().Be(location);
+        address.Port.Should().Be(port);
+        address.Note.Should().Be(note);
+        address.LastSeen.Should().Be(lastSeen);
+        address.ExcludePing.Should().Be(excludePing);
+        address.PTRignore.Should().Be(ptrIgnore);
+        address.PTR.Should().Be(ptr);
+        address.FirewallAddressObject.Should().Be(firewallObject);
+        address.EditDate.Should().Be(editDate);
+        address.CustomerId.Should().Be(customerId);
+        address.ExtendedData.Should().BeEquivalentTo(extendedData);
+    }
+
+    [Fact]
+    public void Constructor_WithNullOptionalFields_SetsNullValues()
+    {
+        // Act
+        var address = new Address(
+            1, 10, "10.0.0.1", false, "", "", "", "",
+            0, 0, "", "", "", null, false,
+            false, 0, "", null, 0, null
+        );
+
+        // Assert
+        address.LastSeen.Should().BeNull();
+        address.EditDate.Should().BeNull();
+        address.ExtendedData.Should().BeNull();
+    }
+
+    [Fact]
+    public void ToString_ReturnsIpAddress()
+    {
+        // Arrange
+        var address = new Address(
+            1, 10, "192.168.1.50", false, "Test", "host.local", "", "",
+            0, 0, "", "", "", null, false,
+            false, 0, "", null, 0, null
+        );
+
+        // Act
+        var result = address.ToString();
+
+        // Assert
+        result.Should().Be("192.168.1.50");
+    }
+
+    [Theory]
+    [InlineData("10.0.0.1")]
+    [InlineData("172.16.0.100")]
+    [InlineData("192.168.255.255")]
+    [InlineData("2001:db8::1")]
+    public void ToString_ReturnsCorrectIp_ForVariousAddresses(string expectedIp)
+    {
+        // Arrange
+        var address = new Address(
+            1, 1, expectedIp, false, "", "", "", "",
+            0, 0, "", "", "", null, false,
+            false, 0, "", null, 0, null
+        );
+
+        // Act & Assert
+        address.ToString().Should().Be(expectedIp);
+    }
+}
diff --git a/classlib.tests/Models/DomainTests.cs b/classlib.tests/Models/DomainTests.cs
new file mode 100644
index 0000000..9655e48
--- /dev/null
+++ b/classlib.tests/Models/DomainTests.cs
@@ -0,0 +1,43 @@
+namespace PS.IPAM.Tests.Models;
+
+using FluentAssertions;
+using PS.IPAM;
+using Xunit;
+
+public class DomainTests
+{
+    [Fact]
+    public void Constructor_SetsAllProperties()
+    {
+        // Arrange
+        var id = 1;
+        var name = "Default";
+        var description = "Default L2 domain";
+        var sections = "1;2;3";
+
+        // Act
+        var domain = new Domain(id, name, description, sections);
+
+        // Assert
+        domain.Id.Should().Be(id);
+        domain.Name.Should().Be(name);
+        domain.Description.Should().Be(description);
+        domain.Sections.Should().Be(sections);
+    }
+
+    [Theory]
+    [InlineData("Default")]
+    [InlineData("Datacenter1")]
+    [InlineData("Branch_Office")]
+    public void ToString_ReturnsDomainName(string domainName)
+    {
+        // Arrange
+        var domain = new Domain(1, domainName, "", "");
+
+        // Act
+        var result = domain.ToString();
+
+        // Assert
+        result.Should().Be(domainName);
+    }
+}
diff --git a/classlib.tests/Models/NameserverTests.cs b/classlib.tests/Models/NameserverTests.cs
new file mode 100644
index 0000000..570cd9f
--- /dev/null
+++ b/classlib.tests/Models/NameserverTests.cs
@@ -0,0 +1,82 @@
+namespace PS.IPAM.Tests.Models;
+
+using FluentAssertions;
+using PS.IPAM;
+using Xunit;
+
+public class NameserverTests
+{
+    [Fact]
+    public void Constructor_SetsAllProperties()
+    {
+        // Arrange
+        var id = 1;
+        var name = "Google DNS";
+        var nameServers = "8.8.8.8;8.8.4.4";
+        var description = "Google Public DNS";
+        var permissions = "{\"3\":\"2\"}";
+        var editDate = new DateTime(2026, 1, 10);
+
+        // Act
+        var nameserver = new Nameserver(id, name, nameServers, description, permissions, editDate);
+
+        // Assert
+        nameserver.Id.Should().Be(id);
+        nameserver.Name.Should().Be(name);
+        nameserver.Description.Should().Be(description);
+        nameserver.Permissions.Should().Be(permissions);
+        nameserver.EditDate.Should().Be(editDate);
+    }
+
+    [Fact]
+    public void Constructor_ParsesNameservers_BySemicolon()
+    {
+        // Arrange
+        var nameServersString = "8.8.8.8;8.8.4.4;1.1.1.1";
+
+        // Act
+        var nameserver = new Nameserver(1, "Test", nameServersString, "", "", null);
+
+        // Assert
+        nameserver.NameServers.Should().HaveCount(3);
+        nameserver.NameServers.Should().ContainInOrder("8.8.8.8", "8.8.4.4", "1.1.1.1");
+    }
+
+    [Fact]
+    public void Constructor_WithSingleNameserver_ReturnsArrayWithOneElement()
+    {
+        // Arrange
+        var nameServersString = "8.8.8.8";
+
+        // Act
+        var nameserver = new Nameserver(1, "Test", nameServersString, "", "", null);
+
+        // Assert
+        nameserver.NameServers.Should().HaveCount(1);
+        nameserver.NameServers[0].Should().Be("8.8.8.8");
+    }
+
+    [Fact]
+    public void Constructor_WithEmptyNameservers_ReturnsArrayWithEmptyString()
+    {
+        // Arrange
+        var nameServersString = "";
+
+        // Act
+        var nameserver = new Nameserver(1, "Test", nameServersString, "", "", null);
+
+        // Assert
+        nameserver.NameServers.Should().HaveCount(1);
+        nameserver.NameServers[0].Should().BeEmpty();
+    }
+
+    [Fact]
+    public void Constructor_WithNullEditDate_SetsNull()
+    {
+        // Act
+        var nameserver = new Nameserver(1, "Test", "8.8.8.8", "", "", null);
+
+        // Assert
+        nameserver.EditDate.Should().BeNull();
+    }
+}
diff --git a/classlib.tests/Models/SectionTests.cs b/classlib.tests/Models/SectionTests.cs
new file mode 100644
index 0000000..cc83c8d
--- /dev/null
+++ b/classlib.tests/Models/SectionTests.cs
@@ -0,0 +1,77 @@
+namespace PS.IPAM.Tests.Models;
+
+using FluentAssertions;
+using PS.IPAM;
+using Xunit;
+
+public class SectionTests
+{
+    [Fact]
+    public void Constructor_SetsAllProperties()
+    {
+        // Arrange
+        var id = 1;
+        var name = "Production";
+        var description = "Production networks section";
+        var masterSectionId = 0;
+        var permissions = "{\"3\":\"2\"}";
+        var strictMode = true;
+        var subnetOrdering = "subnet,asc";
+        var order = 1;
+        var editDate = new DateTime(2026, 1, 5);
+        var showSubnet = true;
+        var showVlan = true;
+        var showVRF = false;
+        var showSupernetOnly = false;
+        var dnsId = 1;
+
+        // Act
+        var section = new Section(
+            id, name, description, masterSectionId, permissions, strictMode,
+            subnetOrdering, order, editDate, showSubnet, showVlan, showVRF,
+            showSupernetOnly, dnsId
+        );
+
+        // Assert
+        section.Id.Should().Be(id);
+        section.Name.Should().Be(name);
+        section.Description.Should().Be(description);
+        section.MasterSectionId.Should().Be(masterSectionId);
+        section.Permissions.Should().Be(permissions);
+        section.StrictMode.Should().Be(strictMode);
+        section.SubnetOrdering.Should().Be(subnetOrdering);
+        section.Order.Should().Be(order);
+        section.EditDate.Should().Be(editDate);
+        section.ShowSubnet.Should().Be(showSubnet);
+        section.ShowVlan.Should().Be(showVlan);
+        section.ShowVRF.Should().Be(showVRF);
+        section.ShowSupernetOnly.Should().Be(showSupernetOnly);
+        section.DNSId.Should().Be(dnsId);
+    }
+
+    [Theory]
+    [InlineData("Production")]
+    [InlineData("Development")]
+    [InlineData("DMZ")]
+    public void ToString_ReturnsSectionName(string sectionName)
+    {
+        // Arrange
+        var section = new Section(1, sectionName, "", 0, "", false, "", 0, null, false, false, false, false, 0);
+
+        // Act
+        var result = section.ToString();
+
+        // Assert
+        result.Should().Be(sectionName);
+    }
+
+    [Fact]
+    public void Constructor_WithNullEditDate_SetsNull()
+    {
+        // Act
+        var section = new Section(1, "Test", "", 0, "", false, "", 0, null, false, false, false, false, 0);
+
+        // Assert
+        section.EditDate.Should().BeNull();
+    }
+}
diff --git a/classlib.tests/Models/SessionTests.cs b/classlib.tests/Models/SessionTests.cs
new file mode 100644
index 0000000..4d9ebb2
--- /dev/null
+++ b/classlib.tests/Models/SessionTests.cs
@@ -0,0 +1,92 @@
+namespace PS.IPAM.Tests.Models;
+
+using FluentAssertions;
+using PS.IPAM;
+using Xunit;
+
+public class SessionTests
+{
+    [Fact]
+    public void Constructor_WithCredentialsAuth_SetsAllProperties()
+    {
+        // Arrange
+        var authType = AuthType.credentials;
+        var token = "test-token-123";
+        var appId = "myApp";
+        var url = "https://ipam.example.com";
+        var expires = new DateTime(2026, 12, 31, 23, 59, 59);
+        var credentials = new object(); // Mock credentials
+
+        // Act
+        var session = new Session(authType, token, appId, url, expires, credentials);
+
+        // Assert
+        session.AuthType.Should().Be(AuthType.credentials);
+        session.Token.Should().Be(token);
+        session.AppID.Should().Be(appId);
+        session.URL.Should().Be(url);
+        session.Expires.Should().Be(expires);
+        session.Credentials.Should().BeSameAs(credentials);
+    }
+
+    [Fact]
+    public void Constructor_WithTokenAuth_SetsAllProperties()
+    {
+        // Arrange
+        var authType = AuthType.token;
+        var token = "static-api-token";
+        var appId = "apiApp";
+        var url = "https://ipam.test.com";
+
+        // Act
+        var session = new Session(authType, token, appId, url, null, null);
+
+        // Assert
+        session.AuthType.Should().Be(AuthType.token);
+        session.Token.Should().Be(token);
+        session.AppID.Should().Be(appId);
+        session.URL.Should().Be(url);
+        session.Expires.Should().BeNull();
+        session.Credentials.Should().BeNull();
+    }
+
+    [Fact]
+    public void Token_CanBeModified()
+    {
+        // Arrange
+        var session = new Session(AuthType.credentials, "old-token", "app", "https://test.com", null, null);
+
+        // Act
+        session.Token = "new-token";
+
+        // Assert
+        session.Token.Should().Be("new-token");
+    }
+
+    [Fact]
+    public void Expires_CanBeModified()
+    {
+        // Arrange
+        var session = new Session(AuthType.credentials, "token", "app", "https://test.com", null, null);
+        var newExpiry = new DateTime(2027, 1, 1);
+
+        // Act
+        session.Expires = newExpiry;
+
+        // Assert
+        session.Expires.Should().Be(newExpiry);
+    }
+
+    [Fact]
+    public void ToString_ReturnsDefaultObjectString()
+    {
+        // Arrange
+        var session = new Session(AuthType.token, "token", "app", "https://test.com", null, null);
+
+        // Act
+        var result = session.ToString();
+
+        // Assert
+        result.Should().Contain("PS.IPAM.Session");
+    }
+}
diff --git a/classlib.tests/Models/SubnetworkTests.cs b/classlib.tests/Models/SubnetworkTests.cs
new file mode 100644
index 0000000..eca5166
--- /dev/null
+++ b/classlib.tests/Models/SubnetworkTests.cs
@@ -0,0 +1,142 @@
+namespace PS.IPAM.Tests.Models;
+
+using FluentAssertions;
+using PS.IPAM;
+using Xunit;
+
+public class SubnetworkTests
+{
+    [Fact]
+    public void Constructor_SetsAllProperties()
+    {
+        // Arrange
+        var id = 1;
+        var subnet = "192.168.1.0";
+        var mask = 24;
+        var sectionId = 5;
+        var description = "Production network";
+        var linkedSubnet = "linked-123";
+        var firewallObject = "FW_PROD";
+        var vrfId = 2;
+        var masterSubnetId = 0;
+        var allowRequests = true;
+        var vlanId = 100;
+        var showName = true;
+        var deviceId = 10;
+        var permissions = "rw";
+        var pingSubnet = true;
+        var discoverSubnet = false;
+        var resolveDNS = true;
+        var dnsRecursive = false;
+        var dnsRecords = true;
+        var nameserverId = 3;
+        var scanAgent = false;
+        var isFolder = false;
+        var isFull = false;
+        var isPool = true;
+        var tagId = 1;
+        var threshold = 80;
+        var locationId = 4;
+        var editDate = new DateTime(2026, 1, 10);
+        var lastScan = new DateTime(2026, 1, 9);
+        var lastDiscovery = new DateTime(2026, 1, 8);
+        var calculation = new { maxhosts = 254 };
+        var customFields = new Dictionary<string, object> { { "custom_env", "prod" } };
+
+        // Act
+        var subnetwork = new Subnetwork(
+            id, subnet, mask, sectionId, description, linkedSubnet, firewallObject,
+            vrfId, masterSubnetId, allowRequests, vlanId, showName, deviceId,
+            permissions, pingSubnet, discoverSubnet, resolveDNS, dnsRecursive,
+            dnsRecords, nameserverId, scanAgent, isFolder, isFull, isPool,
+            tagId, threshold, locationId, editDate, lastScan, lastDiscovery,
+            calculation, customFields
+        );
+
+        // Assert
+        subnetwork.Id.Should().Be(id);
+        subnetwork.Subnet.Should().Be(subnet);
+        subnetwork.Mask.Should().Be(mask);
+        subnetwork.SectionId.Should().Be(sectionId);
+        subnetwork.Description.Should().Be(description);
+        subnetwork.LinkedSubnet.Should().Be(linkedSubnet);
+        subnetwork.FirewallAddressObject.Should().Be(firewallObject);
+        subnetwork.VrfId.Should().Be(vrfId);
+        subnetwork.MasterSubnetId.Should().Be(masterSubnetId);
+        subnetwork.AllowRequests.Should().Be(allowRequests);
+        subnetwork.VlanId.Should().Be(vlanId);
+        subnetwork.ShowName.Should().Be(showName);
+        subnetwork.DeviceId.Should().Be(deviceId);
+        subnetwork.Permissions.Should().Be(permissions);
+        subnetwork.PingSubnet.Should().Be(pingSubnet);
+        subnetwork.DiscoverSubnet.Should().Be(discoverSubnet);
+        subnetwork.ResolveDNS.Should().Be(resolveDNS);
+        subnetwork.DNSRecursive.Should().Be(dnsRecursive);
+        subnetwork.DNSRecords.Should().Be(dnsRecords);
+        subnetwork.NameserverId.Should().Be(nameserverId);
+        subnetwork.ScanAgent.Should().Be(scanAgent);
+        subnetwork.IsFolder.Should().Be(isFolder);
+        subnetwork.IsFull.Should().Be(isFull);
+        subnetwork.IsPool.Should().Be(isPool);
+        subnetwork.TagId.Should().Be(tagId);
+        subnetwork.Threshold.Should().Be(threshold);
+        subnetwork.LocationId.Should().Be(locationId);
+        subnetwork.EditDate.Should().Be(editDate);
+        subnetwork.LastScan.Should().Be(lastScan);
+        subnetwork.LastDiscovery.Should().Be(lastDiscovery);
+        subnetwork.Calculation.Should().BeEquivalentTo(calculation);
+        subnetwork.ExtendedData.Should().BeEquivalentTo(customFields);
+    }
+
+    [Theory]
+    [InlineData("192.168.1.0", 24, "192.168.1.0/24")]
+    [InlineData("10.0.0.0", 8, "10.0.0.0/8")]
+    [InlineData("172.16.0.0", 16, "172.16.0.0/16")]
+    [InlineData("192.168.100.0", 30, "192.168.100.0/30")]
+    public void GetCIDR_ReturnsCidrNotation(string subnet, int mask, string expectedCidr)
+    {
+        // Arrange
+        var subnetwork = CreateSubnetwork(subnet, mask);
+
+        // Act
+        var result = subnetwork.GetCIDR();
+
+        // Assert
+        result.Should().Be(expectedCidr);
+    }
+
+    [Fact]
+    public void ToString_ReturnsCidrNotation()
+    {
+        // Arrange
+        var subnetwork = CreateSubnetwork("10.10.0.0", 16);
+
+        // Act
+        var result = subnetwork.ToString();
+
+        // Assert
+        result.Should().Be("10.10.0.0/16");
+    }
+
+    [Fact]
+    public void ToString_EqualsGetCIDR()
+    {
+        // Arrange
+        var subnetwork = CreateSubnetwork("172.20.0.0", 12);
+
+        // Act & Assert
+        subnetwork.ToString().Should().Be(subnetwork.GetCIDR());
+    }
+
+    private static Subnetwork CreateSubnetwork(string subnet, int mask)
+    {
+        return new Subnetwork(
+            1, subnet, mask, 1, "", "", "",
+            0, 0, false, 0, false, 0,
+            "", false, false, false, false,
+            false, 0, false, false, false, false,
+            0, 0, 0, null, null, null,
+            new object(), null
+        );
+    }
+}
diff --git a/classlib.tests/Models/TagTests.cs b/classlib.tests/Models/TagTests.cs
new file mode 100644
index 0000000..db345ef
--- /dev/null
+++ b/classlib.tests/Models/TagTests.cs
@@ -0,0 +1,77 @@
+namespace PS.IPAM.Tests.Models;
+
+using FluentAssertions;
+using PS.IPAM;
+using Xunit;
+
+public class TagTests
+{
+    [Fact]
+    public void Constructor_SetsAllProperties()
+    {
+        // Arrange
+        var id = 1;
+        var type = "Used";
+        var showTag = true;
+        var bgColor = "#5cb85c";
+        var fgColor = "#ffffff";
+        var compress = "Yes";
+        var locked = "No";
+        var updateTag = true;
+
+        // Act
+        var tag = new Tag(id, type, showTag, bgColor, fgColor, compress, locked, updateTag);
+
+        // Assert
+        tag.Id.Should().Be(id);
+        tag.Type.Should().Be(type);
+        tag.ShowTag.Should().Be(showTag);
+        tag.BGColor.Should().Be(bgColor);
+        tag.FGColor.Should().Be(fgColor);
+        tag.Compress.Should().BeTrue();
+        tag.Locked.Should().BeFalse();
+        tag.UpdateTag.Should().Be(updateTag);
+    }
+
+    [Theory]
+    [InlineData("Yes", true)]
+    [InlineData("No", false)]
+    [InlineData("", false)]
+    [InlineData("yes", false)]  // Case sensitive
+    [InlineData("true", false)] // Only "Yes" is true
+    public void StringToBool_ConvertsCorrectly(string input, bool expected)
+    {
+        // The StringToBool is private, so we test through the constructor
+        // Using Compress field which uses StringToBool
+        var tag = new Tag(1, "Test", false, "", "", input, "No", false);
+
+        tag.Compress.Should().Be(expected);
+    }
+
+    [Theory]
+    [InlineData("Used")]
+    [InlineData("Available")]
+    [InlineData("Reserved")]
+    [InlineData("DHCP")]
+    public void ToString_ReturnsTagType(string tagType)
+    {
+        // Arrange
+        var tag = new Tag(1, tagType, false, "", "", "No", "No", false);
+
+        // Act
+        var result = tag.ToString();
+
+        // Assert
+        result.Should().Be(tagType);
+    }
+
+    [Fact]
+    public void Locked_WithYes_IsTrue()
+    {
+        // Arrange & Act
+        var tag = new Tag(1, "Test", false, "", "", "No", "Yes", false);
+
+        // Assert
+        tag.Locked.Should().BeTrue();
+    }
+}
diff --git a/classlib.tests/Models/VlanTests.cs b/classlib.tests/Models/VlanTests.cs
new file mode 100644
index 0000000..066956a
--- /dev/null
+++ b/classlib.tests/Models/VlanTests.cs
@@ -0,0 +1,76 @@
+namespace PS.IPAM.Tests.Models;
+
+using FluentAssertions;
+using PS.IPAM;
+using Xunit;
+
+public class VlanTests
+{
+    [Fact]
+    public void Constructor_SetsAllProperties()
+    {
+        // Arrange
+        var vlanId = 100;
+        var domainId = 1;
+        var name = "Production VLAN";
+        var number = 100;
+        var description = "Production network VLAN";
+        var editDate = new DateTime(2026, 1, 15);
+        var customerId = 50;
+        var customFields = new Dictionary<string, object> { { "custom_location", "DC1" } };
+
+        // Act
+        var vlan = new Vlan(vlanId, domainId, name, number, description, editDate, customerId, customFields);
+
+        // Assert
+        vlan.Id.Should().Be(vlanId);
+        vlan.VlanId.Should().Be(vlanId);
+        vlan.DomainId.Should().Be(domainId);
+        vlan.Name.Should().Be(name);
+        vlan.Number.Should().Be(number);
+        vlan.Description.Should().Be(description);
+        vlan.EditDate.Should().Be(editDate);
+        vlan.CustomerId.Should().Be(customerId);
+        vlan.ExtendedData.Should().BeEquivalentTo(customFields);
+    }
+
+    [Fact]
+    public void Id_And_VlanId_AreSameValue()
+    {
+        // Arrange
+        var vlanId = 200;
+
+        // Act
+        var vlan = new Vlan(vlanId, 1, "Test", 200, "", null, 0, null);
+
+        // Assert
+        vlan.Id.Should().Be(vlan.VlanId);
+    }
+
+    [Theory]
+    [InlineData(1)]
+    [InlineData(100)]
+    [InlineData(4094)]
+    public void ToString_ReturnsVlanNumber(int vlanNumber)
+    {
+        // Arrange
+        var vlan = new Vlan(1, 1, "Test", vlanNumber, "", null, 0, null);
+
+        // Act
+        var result = vlan.ToString();
+
+        // Assert
+        result.Should().Be(vlanNumber.ToString());
+    }
+
+    [Fact]
+    public void Constructor_WithNullOptionalFields_SetsNullValues()
+    {
+        // Act
+        var vlan = new Vlan(1, 1, "Test", 10, "", null, 0, null);
+
+        // Assert
+        vlan.EditDate.Should().BeNull();
+        vlan.ExtendedData.Should().BeNull();
+    }
+}
diff --git a/classlib.tests/Models/VrfTests.cs b/classlib.tests/Models/VrfTests.cs
new file mode 100644
index 0000000..d494dbb
--- /dev/null
+++ b/classlib.tests/Models/VrfTests.cs
@@ -0,0 +1,60 @@
+namespace PS.IPAM.Tests.Models;
+
+using FluentAssertions;
+using PS.IPAM;
+using Xunit;
+
+public class VrfTests
+{
+    [Fact]
+    public void Constructor_SetsAllProperties()
+    {
+        // Arrange
+        var id = 1;
+        var name = "VRF_PROD";
+        var rd = "65000:100";
+        var description = "Production VRF";
+        var sections = "1;2;3";
+        var editDate = new DateTime(2026, 1, 10);
+        var customFields = new Dictionary<string, object> { { "custom_tenant", "CustomerA" } };
+
+        // Act
+        var vrf = new Vrf(id, name, rd, description, sections, editDate, customFields);
+
+        // Assert
+        vrf.Id.Should().Be(id);
+        vrf.Name.Should().Be(name);
+        vrf.RouteDistinguisher.Should().Be(rd);
+        vrf.Description.Should().Be(description);
+        vrf.Sections.Should().Be(sections);
+        vrf.EditDate.Should().Be(editDate);
+        vrf.ExtendedData.Should().BeEquivalentTo(customFields);
+    }
+
+    [Theory]
+    [InlineData("VRF_DEFAULT")]
+    [InlineData("Production_VRF")]
+    [InlineData("CUSTOMER_A")]
+    public void ToString_ReturnsVrfName(string vrfName)
+    {
+        // Arrange
+        var vrf = new Vrf(1, vrfName, "65000:1", "", "", null, null);
+
+        // Act
+        var result = vrf.ToString();
+
+        // Assert
+        result.Should().Be(vrfName);
+    }
+
+    [Fact]
+    public void Constructor_WithNullOptionalFields_SetsNullValues()
+    {
+        // Act
+        var vrf = new Vrf(1, "Test", "65000:1", "", "", null, null);
+
+        // Assert
+        vrf.EditDate.Should().BeNull();
+        vrf.ExtendedData.Should().BeNull();
+    }
+}
diff --git a/classlib.tests/classlib.tests.csproj b/classlib.tests/classlib.tests.csproj
new file mode 100644
index 0000000..0c4f99c
--- /dev/null
+++ b/classlib.tests/classlib.tests.csproj
@@ -0,0 +1,33 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <LangVersion>latest</LangVersion>
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+    <RootNamespace>PS.IPAM.Tests</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="xunit" Version="2.6.4" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.5.5">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="coverlet.collector" Version="6.0.0">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="Moq" Version="4.20.70" />
+    <PackageReference Include="FluentAssertions" Version="6.12.0" />
+    <PackageReference Include="PowerShellStandard.Library" Version="5.1.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\classlib\classlib.csproj" />
+  </ItemGroup>
+
+</Project>