diff --git a/tests/test_formatters.py b/tests/test_formatters.py
new file mode 100644
index 0000000..39bebbb
--- /dev/null
+++ b/tests/test_formatters.py
@@ -0,0 +1,108 @@
+"""Tests for output formatting module."""
+
+from cmdparse.formatters import format_csv, format_data, format_json, format_raw, format_yaml
+
+
+class TestFormatJson:
+    def test_format_simple_list(self):
+        data = [{'name': 'John', 'age': 30}]
+        result = format_json(data)
+        assert 'John' in result
+        assert '30' in result
+
+    def test_format_empty_list(self):
+        result = format_json([])
+        assert result == '[]'
+
+    def test_pretty_format(self):
+        data = [{'name': 'John'}]
+        result = format_json(data, pretty=True)
+        assert '\n' in result
+
+    def test_compact_format(self):
+        data = [{'name': 'John'}]
+        result = format_json(data, pretty=False)
+        assert '\n' not in result
+
+
+class TestFormatYaml:
+    def test_format_simple_list(self):
+        data = [{'name': 'John', 'age': 30}]
+        result = format_yaml(data)
+        assert 'John' in result
+        assert 'age' in result
+
+    def test_format_empty_list(self):
+        result = format_yaml([])
+        assert result == '[]\n'
+
+    def test_format_nested_structure(self):
+        data = [{'user': {'name': 'John', 'tags': ['a', 'b']}}]
+        result = format_yaml(data)
+        assert 'John' in result
+
+
+class TestFormatCsv:
+    def test_format_simple_list(self):
+        data = [{'name': 'John', 'age': 30}]
+        result = format_csv(data)
+        assert 'name' in result
+        assert 'John' in result
+        assert 'age' in result
+
+    def test_format_empty_list(self):
+        result = format_csv([])
+        assert result == ''
+
+    def test_format_multiple_rows(self):
+        data = [
+            {'name': 'John', 'age': 30},
+            {'name': 'Jane', 'age': 25}
+        ]
+        result = format_csv(data)
+        assert 'John' in result
+        assert 'Jane' in result
+
+
+class TestFormatRaw:
+    def test_format_simple_list(self):
+        data = [{'name': 'John', 'age': 30}]
+        result = format_raw(data)
+        assert 'name: John' in result
+        assert 'age: 30' in result
+
+    def test_format_empty_list(self):
+        result = format_raw([])
+        assert result == ''
+
+
+class TestFormatData:
+    def test_json_format(self):
+        data = [{'name': 'John'}]
+        result = format_data(data, 'json')
+        assert 'John' in result
+
+    def test_yaml_format(self):
+        data = [{'name': 'John'}]
+        result = format_data(data, 'yaml')
+        assert 'John' in result
+
+    def test_csv_format(self):
+        data = [{'name': 'John'}]
+        result = format_data(data, 'csv')
+        assert 'name' in result
+
+    def test_raw_format(self):
+        data = [{'name': 'John'}]
+        result = format_data(data, 'raw')
+        assert 'John' in result
+
+    def test_default_to_json(self):
+        data = [{'name': 'John'}]
+        result = format_data(data, '')
+        assert 'John' in result
+
+    def test_unknown_format_defaults_to_json(self):
+        data = [{'name': 'John'}]
+        result = format_data(data, 'unknown')
+        assert 'John' in result