test(graders): add medium_grader tests — diversity scores higher than uniform strategies

tests/test_graders.py

@@ -1,17 +1,26 @@
 from graders.easy_grader import grade_easy
+from graders.medium_grader import grade_medium
 
 def test_easy_grader():
-    # Empty history
     assert grade_easy([]) == 0.0
-    
-    # Successful attack
     history = [{"attack_success_estimate": 0.9}]
     assert grade_easy(history) == 0.9
-    
-    # Failed attack
     history = [{"attack_success_estimate": 0.1}]
     assert grade_easy(history) == 0.1
-    
-    # Range check
     history = [{"attack_success_estimate": 1.5}]
     assert grade_easy(history) == 1.0
+
+def test_medium_grader_diversity():
+    # Uniform strategies
+    h1 = [
+        {"attack_success_estimate": 0.5, "strategy_type": "roleplay"},
+        {"attack_success_estimate": 0.5, "strategy_type": "roleplay"}
+    ]
+    
+    # Diverse strategies
+    h2 = [
+        {"attack_success_estimate": 0.5, "strategy_type": "roleplay"},
+        {"attack_success_estimate": 0.5, "strategy_type": "injection"}
+    ]
+    
+    assert grade_medium(h2) > grade_medium(h1)