diff --git a/test_team_aggie_annihilators.py b/test_team_aggie_annihilators.py
index e77d754..d91252a 100644
--- a/test_team_aggie_annihilators.py
+++ b/test_team_aggie_annihilators.py
@@ -20,10 +20,30 @@ def test_au_acn(self):
 
     def test_au_medicare(self):
         """Test AU_MEDICARE functionality"""
+        # --- Positive (valid checksum) ---
+        valid_numbers = [
+            "My Medicare number is 2123 45670 1",
+            "Medicare number 2123456701",  # no spaces
+        ]
+        for text in valid_numbers:
+            result = analyze_text(text, ["AU_MEDICARE"])
+            self.assertGreater(len(result), 0, f"Expected AU_MEDICARE detected in: {text}")
+            self.assertEqual(result[0].entity_type, "AU_MEDICARE")
+
+        # --- Negative (invalid checksum or format) ---
+        invalid_numbers = [
+            "My number is 7123 45670 1",     # invalid prefix (7 not allowed)
+            "Medicare 12345678",             # too short
+            "Medicare 2123-45670-1",         # dashes (not supported in default patterns)
+            "My medicare info is hidden",    # no number
+        ]
+        for text in invalid_numbers:
+            result = analyze_text(text, ["AU_MEDICARE"])
+            self.assertEqual(result, [], f"Should NOT detect AU_MEDICARE in: {text}")
 
     def test_au_tfn(self):
         """Test AU_TFN functionality"""
 
 
 if __name__ == '__main__':
-    unittest.main()
+    unittest.main()
\ No newline at end of file