diff --git a/tests/test_caldav_client.py b/tests/test_caldav_client.py
index 6b74a4c..03bda2f 100644
--- a/tests/test_caldav_client.py
+++ b/tests/test_caldav_client.py
@@ -1,10 +1,11 @@
-"""Tests for the caldav_client module."""
+"""Tests for the connect_to_caldav function."""
 
 from unittest.mock import MagicMock
 
 import pytest
+from caldav import DAVClient, Principal
 
-from src.caldav_client import get_calendar
+from src.caldav_client import connect_to_caldav, get_calendar
 
 
 def test_get_calendar_found(mock_caldav_principal):
@@ -28,3 +29,92 @@ def test_get_calendar_not_found(mock_caldav_principal):
 
     with pytest.raises(ValueError, match=f"No calendar named '{calendar_name}' found"):
         get_calendar(mock_caldav_principal, calendar_name)
+
+
+def test_connect_to_caldav_successful(mocker):
+    """Test successful connection to CalDAV server."""
+    mock_client = mocker.MagicMock(spec=DAVClient)
+    mock_principal = mocker.MagicMock(spec=Principal)
+    mock_client.principal.return_value = mock_principal
+
+    mock_davclient = mocker.patch("src.caldav_client.DAVClient", return_value=mock_client)
+
+    url = "https://caldav.example.com"
+    username = "testuser"
+    password = "testpass"
+
+    result = connect_to_caldav(url, username, password)
+
+    mock_davclient.assert_called_once_with(url, username=username, password=password)
+
+    mock_client.principal.assert_called_once()
+
+    assert result == mock_principal
+
+
+def test_connect_to_caldav_authentication_error(mocker):
+    """Test handling of authentication errors."""
+    mock_client = mocker.MagicMock(spec=DAVClient)
+    mock_client.principal.side_effect = Exception("Authentication failed")
+    mocker.patch("src.caldav_client.DAVClient", return_value=mock_client)
+
+    with pytest.raises(Exception, match="Authentication failed"):
+        connect_to_caldav("https://caldav.example.com", "wronguser", "wrongpass")
+
+
+def test_connect_to_caldav_connection_error(mocker):
+    """Test handling of connection errors."""
+    mocker.patch(
+        "src.caldav_client.DAVClient",
+        side_effect=Exception("Could not connect to server"),
+    )
+
+    with pytest.raises(Exception, match="Could not connect to server"):
+        connect_to_caldav("https://invalid.example.com", "user", "pass")
+
+
+def test_connect_to_caldav_invalid_url(mocker):
+    """Test handling of invalid URL."""
+    mocker.patch(
+        "src.caldav_client.DAVClient",
+        side_effect=ValueError("Invalid URL format"),
+    )
+
+    with pytest.raises(ValueError, match="Invalid URL format"):
+        connect_to_caldav("not-a-url", "user", "pass")
+
+
+def test_connect_to_caldav_empty_credentials(mocker):
+    """Test handling of empty credentials."""
+    mock_client = mocker.MagicMock(spec=DAVClient)
+    mock_davclient = mocker.patch("src.caldav_client.DAVClient", return_value=mock_client)
+
+    connect_to_caldav("https://caldav.example.com", "", "")
+
+    mock_davclient.assert_called_once_with(
+        "https://caldav.example.com",
+        username="",
+        password="",
+    )
+
+
+def test_connect_to_caldav_ssl_error(mocker):
+    """Test handling of SSL certificate errors."""
+    mocker.patch(
+        "src.caldav_client.DAVClient",
+        side_effect=Exception("SSL certificate verification failed"),
+    )
+
+    with pytest.raises(Exception, match="SSL certificate verification failed"):
+        connect_to_caldav("https://selfsigned.example.com", "user", "pass")
+
+
+def test_connect_to_caldav_timeout(mocker):
+    """Test handling of connection timeout."""
+    mocker.patch(
+        "src.caldav_client.DAVClient",
+        side_effect=Exception("Connection timed out"),
+    )
+
+    with pytest.raises(Exception, match="Connection timed out"):
+        connect_to_caldav("https://slow.example.com", "user", "pass")