diff --git a/tests/test_custom_patterns.py b/tests/test_custom_patterns.py
new file mode 100644
index 0000000..59d1e40
--- /dev/null
+++ b/tests/test_custom_patterns.py
@@ -0,0 +1,151 @@
+"""Tests for custom patterns module."""
+
+import pytest
+from pathlib import Path
+
+from gitignore_cli.custom_patterns import (
+    CustomPattern,
+    CustomPatternManager,
+)
+
+
+class TestCustomPattern:
+    """Tests for CustomPattern class."""
+
+    def test_custom_pattern_creation(self):
+        """Test creating a CustomPattern instance."""
+        pattern = CustomPattern(pattern="*.log", description="Log files")
+
+        assert pattern.pattern == "*.log"
+        assert pattern.description == "Log files"
+        assert pattern.enabled is True
+
+    def test_custom_pattern_disabled(self):
+        """Test creating a disabled CustomPattern."""
+        pattern = CustomPattern(pattern="*.tmp", enabled=False)
+
+        assert pattern.enabled is False
+
+    def test_custom_pattern_to_dict(self):
+        """Test converting pattern to dictionary."""
+        pattern = CustomPattern(pattern="*.log", description="Logs", enabled=True)
+        data = pattern.to_dict()
+
+        assert data["pattern"] == "*.log"
+        assert data["description"] == "Logs"
+        assert data["enabled"] is True
+
+    def test_custom_pattern_from_dict(self):
+        """Test creating pattern from dictionary."""
+        data = {
+            "pattern": "*.tmp",
+            "description": "Temporary files",
+            "enabled": False,
+        }
+        pattern = CustomPattern.from_dict(data)
+
+        assert pattern.pattern == "*.tmp"
+        assert pattern.description == "Temporary files"
+        assert pattern.enabled is False
+
+    def test_custom_pattern_repr(self):
+        """Test pattern string representation."""
+        pattern = CustomPattern(pattern="*.log")
+        repr_str = repr(pattern)
+
+        assert "*.log" in repr_str
+
+
+class TestCustomPatternManager:
+    """Tests for CustomPatternManager class."""
+
+    def test_add_pattern(self, custom_pattern_manager: CustomPatternManager):
+        """Test adding a custom pattern."""
+        result = custom_pattern_manager.add_pattern("*.log", "Log files")
+
+        assert result is True
+        assert custom_pattern_manager.count() == 1
+
+    def test_add_duplicate_pattern(self, custom_pattern_manager: CustomPatternManager):
+        """Test adding a duplicate pattern."""
+        custom_pattern_manager.add_pattern("*.log")
+
+        result = custom_pattern_manager.add_pattern("*.log")
+        assert result is False
+
+    def test_remove_pattern(self, custom_pattern_manager: CustomPatternManager):
+        """Test removing a custom pattern."""
+        custom_pattern_manager.add_pattern("*.log")
+
+        result = custom_pattern_manager.remove_pattern("*.log")
+        assert result is True
+        assert custom_pattern_manager.count() == 0
+
+    def test_remove_nonexistent_pattern(self, custom_pattern_manager: CustomPatternManager):
+        """Test removing a pattern that doesn't exist."""
+        result = custom_pattern_manager.remove_pattern("*.nonexistent")
+        assert result is False
+
+    def test_list_patterns(self, custom_pattern_manager: CustomPatternManager):
+        """Test listing custom patterns."""
+        custom_pattern_manager.add_pattern("*.log", "Log files")
+        custom_pattern_manager.add_pattern("*.tmp")
+        custom_pattern_manager.toggle_pattern("*.tmp")
+
+        patterns = custom_pattern_manager.list_patterns(include_disabled=True)
+        assert len(patterns) == 2
+
+        enabled = custom_pattern_manager.list_patterns(include_disabled=False)
+        assert len(enabled) == 1
+
+    def test_get_enabled_patterns(self, custom_pattern_manager: CustomPatternManager):
+        """Test getting enabled pattern strings."""
+        custom_pattern_manager.add_pattern("*.log")
+        custom_pattern_manager.add_pattern("*.tmp")
+        custom_pattern_manager.toggle_pattern("*.tmp")
+
+        patterns = custom_pattern_manager.get_enabled_patterns()
+        assert "*.log" in patterns
+        assert "*.tmp" not in patterns
+
+    def test_toggle_pattern(self, custom_pattern_manager: CustomPatternManager):
+        """Test toggling a pattern's enabled state."""
+        custom_pattern_manager.add_pattern("*.log")
+
+        new_state = custom_pattern_manager.toggle_pattern("*.log")
+        assert new_state is False
+
+        new_state = custom_pattern_manager.toggle_pattern("*.log")
+        assert new_state is True
+
+    def test_toggle_nonexistent_pattern(self, custom_pattern_manager: CustomPatternManager):
+        """Test toggling a nonexistent pattern."""
+        result = custom_pattern_manager.toggle_pattern("*.nonexistent")
+        assert result is None
+
+    def test_get_patterns_content(self, custom_pattern_manager: CustomPatternManager):
+        """Test getting patterns content string."""
+        custom_pattern_manager.add_pattern("*.log")
+        custom_pattern_manager.add_pattern("*.tmp")
+
+        content = custom_pattern_manager.get_patterns_content()
+
+        assert "*.log" in content
+        assert "*.tmp" in content
+
+    def test_count_patterns(self, custom_pattern_manager: CustomPatternManager):
+        """Test counting patterns."""
+        assert custom_pattern_manager.count() == 0
+
+        custom_pattern_manager.add_pattern("*.log")
+        custom_pattern_manager.add_pattern("*.tmp")
+
+        assert custom_pattern_manager.count() == 2
+
+    def test_count_enabled(self, custom_pattern_manager: CustomPatternManager):
+        """Test counting enabled patterns."""
+        custom_pattern_manager.add_pattern("*.log")
+        custom_pattern_manager.add_pattern("*.tmp")
+        custom_pattern_manager.toggle_pattern("*.tmp")
+
+        assert custom_pattern_manager.count_enabled() == 1