diff --git a/app/tests/test_patterns.py b/app/tests/test_patterns.py
new file mode 100644
index 0000000..410ad08
--- /dev/null
+++ b/app/tests/test_patterns.py
@@ -0,0 +1,36 @@
+import pytest
+from cmdparse.patterns import detect_pattern_type, PATTERNS
+
+
+def test_detect_table_with_pipes():
+    """Test detection of table format with pipe separators."""
+    text = "| Name | Age |\n| Alice | 30 |"
+    assert detect_pattern_type(text) == 'table'
+
+
+def test_detect_key_value_colon():
+    """Test detection of key-value with colon."""
+    text = "key1: value1\nkey2: value2"
+    assert detect_pattern_type(text) == 'key_value_colon'
+
+
+def test_detect_delimited_tab():
+    """Test detection of tab-delimited format."""
+    text = "name\tage\tcity\nalice\t30\tnyc"
+    assert detect_pattern_type(text) == 'delimited_tab'
+
+
+def test_detect_empty():
+    """Test detection of empty input."""
+    assert detect_pattern_type("") == 'empty'
+
+
+def test_detect_raw():
+    """Test detection of raw/unstructured text."""
+    text = "some random text without pattern"
+    assert detect_pattern_type(text) == 'raw'
+
+
+def test_patterns_not_empty():
+    """Test that PATTERNS list is not empty."""
+    assert len(PATTERNS) > 0