Python: Improve customSanitizer tests

Before we didn't show how we treated the value _after_ the check. But we
do actually handle this nicely 💪

Author: RasmusWL

python/ql/test/experimental/dataflow/tainttracking/customSanitizer/InlineTaintTest.expected

@@ -3,9 +3,9 @@ untaintedArgumentToEnsureTaintedNotMarkedAsMissing
 failures
 isSanitizer
 | TestTaintTrackingConfiguration | test.py:21:39:21:39 | ControlFlowNode for s |
-| TestTaintTrackingConfiguration | test.py:50:10:50:29 | ControlFlowNode for emulated_escaping() |
+| TestTaintTrackingConfiguration | test.py:53:10:53:29 | ControlFlowNode for emulated_escaping() |
 isSanitizerGuard
-| TestTaintTrackingConfiguration | test.py:35:8:35:26 | ControlFlowNode for emulated_is_safe() |
+| TestTaintTrackingConfiguration | test.py:38:8:38:26 | ControlFlowNode for emulated_is_safe() |
 | TestTaintTrackingConfiguration | test_logical.py:29:8:29:17 | ControlFlowNode for is_safe() |
 | TestTaintTrackingConfiguration | test_logical.py:44:8:44:17 | ControlFlowNode for is_safe() |
 | TestTaintTrackingConfiguration | test_logical.py:52:12:52:21 | ControlFlowNode for is_safe() |

python/ql/test/experimental/dataflow/tainttracking/customSanitizer/test.py

@@ -14,14 +14,17 @@ def emulated_authentication_check(arg):
         raise Exception("user unauthenticated")
 
 
-def test_custom_sanitizer():
+def test_custom_sanitizer_exception():
     s = TAINTED_STRING
 
     try:
         emulated_authentication_check(s)
         ensure_not_tainted(s)
     except:
-        pass
+        ensure_tainted(s) # $ tainted
+        raise
+
+    ensure_not_tainted(s)
 
 
 def emulated_is_safe(arg):
@@ -34,11 +37,11 @@ def test_custom_sanitizer_guard():
 
     if emulated_is_safe(s):
         ensure_not_tainted(s)
-        s = TAINTED_STRING
-        ensure_tainted(s) # $ tainted
     else:
         ensure_tainted(s) # $ tainted
 
+    ensure_tainted(s) # $ tainted
+
 
 def emulated_escaping(arg):
     return arg.replace("<", "?").replace(">", "?").replace("'", "?").replace("\"", "?")
@@ -53,6 +56,9 @@ def test_escape():
 
 # Make tests runable
 
-test_custom_sanitizer()
+try:
+    test_custom_sanitizer_exception()
+except Exception:
+    pass
 test_custom_sanitizer_guard()
 test_escape()