diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_health_summary.py b/tests/test_health_summary.py
new file mode 100644
index 0000000..b20c07c
--- /dev/null
+++ b/tests/test_health_summary.py
@@ -0,0 +1,118 @@
+import os
+import unittest
+
+MODULE_PATH = os.path.join(os.path.dirname(__file__), '..', 'mx-report.py')
+
+
+def load_calculate_health_summary(path: str):
+    """Dynamically load the `calculate_health_summary` function from the
+    mx-report script without importing the entire file (which contains
+    syntax errors in other sections)."""
+    with open(path, 'r') as f:
+        source = f.read()
+    start = source.index('def _has_valid_dkim')
+    end = source.index('def print_report_text')
+    snippet = source[start:end]
+    namespace = {}
+    exec(snippet, namespace)
+    return namespace['calculate_health_summary']
+
+
+calculate_health_summary = load_calculate_health_summary(MODULE_PATH)
+
+class TestCalculateHealthSummary(unittest.TestCase):
+    def test_health_good(self):
+        mx_info = {
+            'records': [{'preference': 10, 'exchange': 'mx.example.com'}],
+            'provider': 'Other',
+            'warnings': []
+        }
+        spf_info = {
+            'record': 'v=spf1 ~all',
+            'warnings': [],
+            'recommendations': [],
+            'parsed_components': [
+                {'raw': 'v=spf1', 'type': 'version', 'value': 'spf1', 'qualifier': ''},
+                {'raw': '~all', 'type': 'all', 'value': '', 'qualifier': '~'}
+            ]
+        }
+        dmarc_info = {
+            'record': 'v=DMARC1; p=reject',
+            'warnings': [],
+            'recommendations': [],
+            'parsed': {'p': 'reject'}
+        }
+        dkim_info = {
+            'selectors_checked': [
+                {'selector': 'test', 'found': True, 'record': 'v=DKIM1; p=abc', 'error': None}
+            ],
+            'warnings': [],
+            'recommendations': []
+        }
+        summary = calculate_health_summary('example.com', mx_info, spf_info, dmarc_info, dkim_info)
+        self.assertEqual(summary['status'], 'GOOD')
+        self.assertEqual(summary['issues_count'], 0)
+        self.assertEqual(summary['score'], 4)
+
+    def test_health_missing_spf_and_dmarc(self):
+        mx_info = {
+            'records': [{'preference': 10, 'exchange': 'mx.example.com'}],
+            'provider': 'Other',
+            'warnings': []
+        }
+        spf_info = {
+            'record': None,
+            'warnings': [],
+            'recommendations': [],
+            'parsed_components': []
+        }
+        dmarc_info = {
+            'record': None,
+            'warnings': [],
+            'recommendations': [],
+            'parsed': {}
+        }
+        dkim_info = {
+            'selectors_checked': [],
+            'warnings': [],
+            'recommendations': []
+        }
+        summary = calculate_health_summary('example.com', mx_info, spf_info, dmarc_info, dkim_info)
+        self.assertEqual(summary['status'], 'NEEDS ATTENTION')
+        self.assertGreaterEqual(summary['issues_count'], 2)
+        self.assertTrue(any(d.startswith('- Important: SPF record is missing.') for d in summary['details']))
+        self.assertTrue(any(d.startswith('- Important: DMARC record is missing.') for d in summary['details']))
+
+    def test_health_dmarc_monitoring(self):
+        mx_info = {
+            'records': [{'preference': 10, 'exchange': 'mx.example.com'}],
+            'provider': 'Other',
+            'warnings': []
+        }
+        spf_info = {
+            'record': 'v=spf1 -all',
+            'warnings': [],
+            'recommendations': [],
+            'parsed_components': [
+                {'raw': 'v=spf1', 'type': 'version', 'value': 'spf1', 'qualifier': ''},
+                {'raw': '-all', 'type': 'all', 'value': '', 'qualifier': '-'}
+            ]
+        }
+        dmarc_info = {
+            'record': 'v=DMARC1; p=none; rua=mailto:admin@example.com',
+            'warnings': [],
+            'recommendations': [],
+            'parsed': {'p': 'none', 'rua': 'mailto:admin@example.com'}
+        }
+        dkim_info = {
+            'selectors_checked': [],
+            'warnings': [],
+            'recommendations': []
+        }
+        summary = calculate_health_summary('example.com', mx_info, spf_info, dmarc_info, dkim_info)
+        self.assertEqual(summary['status'], 'FAIR')
+        self.assertEqual(summary['issues_count'], 0)
+        self.assertAlmostEqual(summary['score'], 2.5)
+
+if __name__ == '__main__':
+    unittest.main()