Issue #4 - add special handling for IndexError exceptions raised in user parse actions

1 files changed, 22 insertions, 0 deletions

diff --git a/unitTests.py b/unitTests.py
index 9966012..ba84898 100644
--- a/unitTests.py
+++ b/unitTests.py
@@ -3489,6 +3489,28 @@ class LiteralExceptionTest(ParseTestCase):
                 print(cls.__name__, str(e))

                 assert isinstance(e, pp.ParseBaseException), "class {} raised wrong exception type {}".format(cls.__name__, type(e).__name__)

 

+class ParseActionExceptionTest(ParseTestCase):

+    def runTest(self):

+        import pyparsing as pp

+        import traceback

+        

+        number = pp.Word(pp.nums)

+        def number_action():

+            raise IndexError # this is the important line!

+

+        number.setParseAction(number_action)

+        symbol = pp.Word('abcd', max=1)

+        expr = number | symbol

+        with self.assertRaises(pp.ParseException):

+            try:

+                expr.parseString('1 + 2')

+            except Exception as e:

+                assert hasattr(e, '__cause__'), "no __cause__ attribute in the raised exception"

+                assert e.__cause__ is not None, "__cause__ not propagated to outer exception"

+                assert type(e.__cause__) == IndexError, "__cause__ references wrong exception"

+                traceback.print_exc()

+                raise

+

 class MiscellaneousParserTests(ParseTestCase):

     def runTest(self):

         import pyparsing