diff --git a/tests/unit/test_formatters.py b/tests/unit/test_formatters.py
new file mode 100644
index 0000000..c48ba61
--- /dev/null
+++ b/tests/unit/test_formatters.py
@@ -0,0 +1,95 @@
+import pytest
+from io import StringIO
+from errorfix.formatters import TextFormatter, JSONFormatter
+from errorfix.patterns import MatchResult
+from errorfix.rules import Rule
+
+
+class TestTextFormatter:
+    def test_format_single_match(self):
+        rule = Rule(
+            id='test-rule',
+            name='Test Rule',
+            pattern='TestError: .*',
+            fix='Fix it',
+            description='A test rule',
+        )
+        result = MatchResult(
+            rule=rule,
+            matched_text='TestError: something',
+            groups={'message': 'something'},
+        )
+        formatter = TextFormatter(use_colors=False)
+        output = formatter.format([result], 'TestError: something')
+        assert 'Test Rule' in output
+        assert 'Fix it' in output
+        assert 'something' in output
+
+    def test_format_no_match(self):
+        formatter = TextFormatter(use_colors=False)
+        output = formatter.format([], 'Unknown error')
+        assert 'No matching rules found' in output
+
+    def test_write_to_stream(self):
+        rule = Rule(
+            id='test-rule',
+            name='Test Rule',
+            pattern='TestError: .*',
+            fix='Fix it',
+            description='A test rule',
+        )
+        result = MatchResult(rule=rule, matched_text='TestError: test')
+        formatter = TextFormatter(use_colors=False)
+        output = StringIO()
+        formatter.write([result], 'TestError: test', output)
+        assert 'Test Rule' in output.getvalue()
+
+
+class TestJSONFormatter:
+    def test_format_single_match(self):
+        rule = Rule(
+            id='test-rule',
+            name='Test Rule',
+            pattern='TestError: .*',
+            fix='Fix it',
+            description='A test rule',
+        )
+        result = MatchResult(
+            rule=rule,
+            matched_text='TestError: something',
+            groups={'message': 'something'},
+        )
+        formatter = JSONFormatter(pretty=True)
+        output = formatter.format([result], 'TestError: something')
+        assert 'Test Rule' in output
+        assert '"suggested_fix"' in output
+        assert 'something' in output
+
+    def test_format_no_match(self):
+        formatter = JSONFormatter(pretty=True)
+        output = formatter.format([], 'Unknown error')
+        assert '"match_count": 0' in output
+
+    def test_pretty_output(self):
+        formatter = JSONFormatter(pretty=True)
+        rule = Rule(
+            id='test-rule',
+            name='Test Rule',
+            pattern='TestError: .*',
+            fix='Fix it',
+            description='A test rule',
+        )
+        result = MatchResult(rule=rule, matched_text='TestError: test')
+        output = formatter.format([result], 'TestError: test')
+        assert '\n' in output
+
+    def test_compact_output(self):
+        formatter = JSONFormatter(pretty=False)
+        rule = Rule(
+            id='test-rule',
+            name='Test Rule',
+            description='A test rule',
+        )
+        result = MatchResult(rule=rule, matched_text='TestError: test')
+        output = formatter.format([result], 'TestError: test')
+        assert '\n' not in output