Fix forget: check self.lineno, not GLOBAL_PDB.lineno (#160)

pdb.py

@@ -299,8 +299,7 @@ def refresh_stack(self):
             self.print_current_stack_entry()
 
     def forget(self):
-        global GLOBAL_PDB
-        if not hasattr(GLOBAL_PDB, 'lineno'):
+        if not hasattr(self, 'lineno'):
             # Only forget if not used with recursive set_trace.
             super(Pdb, self).forget()
         self.raise_lineno = {}
@@ -371,7 +370,6 @@ def _init_pygments(self):
         return True
 
     stack_entry_regexp = re.compile(r'(.*?)\(([0-9]+?)\)(.*)', re.DOTALL)
-    #
 
     def format_stack_entry(self, frame_lineno, lprefix=': '):
         entry = super(Pdb, self).format_stack_entry(frame_lineno, lprefix)

testing/test_pdb.py

@@ -283,6 +283,50 @@ def fn():
 """)
 
 
+def test_forget_with_new_pdb():
+    """Regression test for having used GLOBAL_PDB in forget.
+
+    This caused "AttributeError: 'NewPdb' object has no attribute 'lineno'",
+    e.g. when pdbpp was used before pytest's debugging plugin was setup, which
+    then later uses a custom Pdb wrapper.
+    """
+    def fn():
+        set_trace()
+
+        class NewPdb(PdbTest, pdb.Pdb):
+            def set_trace(self, *args):
+                print("new_set_trace")
+                super(NewPdb, self).set_trace(*args)
+
+        new_pdb = NewPdb()
+        new_pdb.set_trace()
+
+    check(fn, """
+[NUM] > .*fn()
+-> class NewPdb(PdbTest, pdb.Pdb):
+   5 frames hidden .*
+# c
+new_set_trace
+--Return--
+[NUM] .*set_trace()->None
+-> .*(\\*args)
+   5 frames hidden .*
+# l
+NUM .*
+NUM .*
+NUM .*
+NUM .*
+NUM .*
+NUM .*
+NUM .*
+NUM .*
+NUM .*
+NUM .*
+NUM .*
+# c
+""")
+
+
 def test_single_question_mark():
     def fn():
         def f2(x, y):