Several enhancements to pdb and its test suite.
* added basic test for basic commands
* removed duplication of command docs, and moved them to their implementation
* unified and useful display of exceptions
* output messages and errors using overridable methods (also fixes #1503502)
diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index b6eeaed..96c93f6 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -1898,7 +1898,7 @@
> <doctest foo[1]>(1)<module>()
-> calls_set_trace()
(Pdb) print(foo)
- *** NameError: NameError("name 'foo' is not defined",)
+ *** NameError: name 'foo' is not defined
(Pdb) continue
TestResults(failed=0, attempted=2)
"""