Make the pdb displayhook compatible with the standard displayhook: do not print Nones. Add a test for that.
diff --git a/Lib/pdb.py b/Lib/pdb.py
index eae6296..0751c17 100755
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -210,7 +210,9 @@
"""Custom displayhook for the exec in default(), which prevents
assignment of the _ variable in the builtins.
"""
- print repr(obj)
+ # reproduce the behavior of the standard displayhook, not printing None
+ if obj is not None:
+ print repr(obj)
def default(self, line):
if line[:1] == '!': line = line[1:]
diff --git a/Lib/test/test_pdb.py b/Lib/test/test_pdb.py
index a15538c..6017edc 100644
--- a/Lib/test/test_pdb.py
+++ b/Lib/test/test_pdb.py
@@ -26,6 +26,38 @@
sys.stdin = self.real_stdin
+def write(x):
+ print x
+
+def test_pdb_displayhook():
+ """This tests the custom displayhook for pdb.
+
+ >>> def test_function(foo, bar):
+ ... import pdb; pdb.Pdb().set_trace()
+ ... pass
+
+ >>> with PdbTestInput([
+ ... 'foo',
+ ... 'bar',
+ ... 'for i in range(5): write(i)',
+ ... 'continue',
+ ... ]):
+ ... test_function(1, None)
+ > <doctest test.test_pdb.test_pdb_displayhook[0]>(3)test_function()
+ -> pass
+ (Pdb) foo
+ 1
+ (Pdb) bar
+ (Pdb) for i in range(5): write(i)
+ 0
+ 1
+ 2
+ 3
+ 4
+ (Pdb) continue
+ """
+
+
def test_pdb_skip_modules():
"""This illustrates the simple case of module skipping.
@@ -36,7 +68,7 @@
>>> with PdbTestInput([
... 'step',
- ... 'continue'
+ ... 'continue',
... ]):
... skip_module()
> <doctest test.test_pdb.test_pdb_skip_modules[0]>(4)skip_module()