diff --git a/tests/unit/test_patterns.py b/tests/unit/test_patterns.py
new file mode 100644
index 0000000..c749c7d
--- /dev/null
+++ b/tests/unit/test_patterns.py
@@ -0,0 +1,114 @@
+"""Unit tests for patterns."""
+
+import pytest
+from vibeguard.patterns.definitions import Severity, Pattern, Issue
+from vibeguard.patterns.manager import PatternManager
+
+
+class TestPatternDefinitions:
+    """Tests for pattern definitions."""
+
+    def test_severity_order(self):
+        """Test severity ordering."""
+        assert Severity.CRITICAL.value == "critical"
+        assert Severity.ERROR.value == "error"
+        assert Severity.WARNING.value == "warning"
+        assert Severity.INFO.value == "info"
+
+    def test_pattern_creation(self):
+        """Test pattern creation."""
+        pattern = Pattern(
+            id="TEST001",
+            name="Test Pattern",
+            description="A test pattern",
+            severity=Severity.WARNING,
+            languages=["python"],
+            message="Test message",
+            suggestion="Test suggestion",
+        )
+
+        assert pattern.id == "TEST001"
+        assert pattern.name == "Test Pattern"
+        assert pattern.severity == Severity.WARNING
+        assert "python" in pattern.languages
+
+    def test_issue_to_dict(self):
+        """Test issue to dictionary conversion."""
+        issue = Issue(
+            pattern_id="TEST001",
+            file="test.py",
+            line=10,
+            severity=Severity.WARNING,
+            message="Test message",
+            suggestion="Test suggestion",
+        )
+
+        result = issue.to_dict()
+
+        assert result["pattern"] == "TEST001"
+        assert result["file"] == "test.py"
+        assert result["line"] == 10
+        assert result["severity"] == "warning"
+
+
+class TestPatternManager:
+    """Tests for pattern manager."""
+
+    def test_load_patterns(self):
+        """Test loading all patterns."""
+        manager = PatternManager()
+        manager.load_all_patterns()
+
+        assert len(manager.patterns) > 0
+
+    def test_get_pattern(self):
+        """Test getting a pattern by ID."""
+        manager = PatternManager()
+        manager.load_all_patterns()
+
+        pattern = manager.get_pattern("PY001")
+        assert pattern is not None
+        assert pattern.id == "PY001"
+
+    def test_get_patterns_by_language(self):
+        """Test getting patterns for a specific language."""
+        manager = PatternManager()
+        manager.load_all_patterns()
+
+        python_patterns = manager.get_patterns_by_language("python")
+        assert len(python_patterns) > 0
+
+        for pattern in python_patterns:
+            assert "python" in pattern.languages or "all" in pattern.languages
+
+    def test_get_patterns_by_severity(self):
+        """Test getting patterns by severity."""
+        manager = PatternManager()
+        manager.load_all_patterns()
+
+        error_patterns = manager.get_patterns_by_severity(Severity.ERROR)
+        for pattern in error_patterns:
+            assert pattern.severity == Severity.ERROR
+
+    def test_to_dict(self):
+        """Test converting patterns to dictionary."""
+        manager = PatternManager()
+        manager.load_all_patterns()
+
+        result = manager.to_dict()
+
+        assert isinstance(result, dict)
+        assert len(result) > 0
+        for pattern_id, pattern_data in result.items():
+            assert "id" in pattern_data
+            assert "name" in pattern_data
+            assert "severity" in pattern_data
+
+    def test_pattern_categories(self):
+        """Test that patterns have proper categories."""
+        manager = PatternManager()
+        manager.load_all_patterns()
+
+        for pattern in manager.patterns.values():
+            assert pattern.category is not None
+            assert len(pattern.category) > 0