From 9726fafa98885fd3bec3972da3bda5f5ce91afdf Mon Sep 17 00:00:00 2001
From: Almar Klein <almar.klein@gmail.com>
Date: Sat, 21 Mar 2015 09:26:35 +0100
Subject: [PATCH 1/3] allow postmortem debugging on failed test

---
 _pytest/runner.py | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/_pytest/runner.py b/_pytest/runner.py
index 2932f14c3..8accd3b0c 100644
--- a/_pytest/runner.py
+++ b/_pytest/runner.py
@@ -86,7 +86,17 @@ def pytest_runtest_setup(item):
     item.session._setupstate.prepare(item)
 
 def pytest_runtest_call(item):
-    item.runtest()
+    try:
+        item.runtest()
+    except Exception:
+        # Store trace info to allow postmortem debugging
+        type, value, tb = sys.exc_info()
+        tb = tb.tb_next  # Skip *this* frame
+        sys.last_type = type
+        sys.last_value = value
+        sys.last_traceback = tb
+        del tb  # Get rid of it in this namespace
+        raise
 
 def pytest_runtest_teardown(item, nextitem):
     item.session._setupstate.teardown_exact(item, nextitem)

From 0fc75c962253ed1b712d8ca144a7f6ecc6df1b49 Mon Sep 17 00:00:00 2001
From: Almar Klein <almar.klein@gmail.com>
Date: Sat, 21 Mar 2015 17:06:24 +0100
Subject: [PATCH 2/3] Storing sys.last_traceback: test, docs and changelog

---
 CHANGELOG              |  4 ++++
 doc/en/usage.txt       |  3 +++
 testing/test_runner.py | 15 +++++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/CHANGELOG b/CHANGELOG
index 20a86f0f1..5fed0265a 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,10 @@
 2.7.0.dev (compared to 2.6.4)
 -----------------------------
 
+- On failure, the ``sys.last_value``, ``sys.last_type`` and 
+  ``sys.last_traceback`` are set, so that a user can inspect the error
+  via postmortem debugging.
+
 - fix issue616: conftest.py files and their contained fixutres are now
   properly considered for visibility, independently from the exact
   current working directory and test arguments that are used.
diff --git a/doc/en/usage.txt b/doc/en/usage.txt
index b03b9b9d6..4931e7086 100644
--- a/doc/en/usage.txt
+++ b/doc/en/usage.txt
@@ -87,6 +87,9 @@ failure situation::
     py.test -x --pdb   # drop to PDB on first failure, then end test session
     py.test --pdb --maxfail=3  # drop to PDB for first three failures
 
+Note that on any failure the exception information is stored on 
+``sys.last_traceback``. In interactive use, this allows one to drop
+into postmortem debugging with any debug tool.
 
 Setting a breakpoint / aka ``set_trace()``
 ----------------------------------------------------
diff --git a/testing/test_runner.py b/testing/test_runner.py
index 9a13a6b47..fee1be09b 100644
--- a/testing/test_runner.py
+++ b/testing/test_runner.py
@@ -525,3 +525,18 @@ def test_makereport_getsource(testdir):
     result = testdir.runpytest()
     assert 'INTERNALERROR' not in result.stdout.str()
     result.stdout.fnmatch_lines(['*else: assert False*'])
+
+
+def test_store_except_info_on_eror(testdir):
+    # Simulate item that raises a specific exception
+    class ItemThatRaises:
+        def runtest(self):
+            raise IndexError('TEST')
+    try:
+        runner.pytest_runtest_call(ItemThatRaises())
+    except IndexError:
+        pass
+    # Check that exception info is stored on sys
+    assert sys.last_type is IndexError
+    assert sys.last_value.args[0] == 'TEST'
+    assert sys.last_traceback

From a9b7de8bf0236de9f421c603f1e2e201777735d0 Mon Sep 17 00:00:00 2001
From: Almar Klein <almar.klein@gmail.com>
Date: Sat, 21 Mar 2015 17:26:23 +0100
Subject: [PATCH 3/3] address reviewer comments

---
 doc/en/usage.txt       | 12 ++++++++++--
 testing/test_runner.py |  5 ++++-
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/doc/en/usage.txt b/doc/en/usage.txt
index 4931e7086..e774ebef6 100644
--- a/doc/en/usage.txt
+++ b/doc/en/usage.txt
@@ -88,8 +88,16 @@ failure situation::
     py.test --pdb --maxfail=3  # drop to PDB for first three failures
 
 Note that on any failure the exception information is stored on 
-``sys.last_traceback``. In interactive use, this allows one to drop
-into postmortem debugging with any debug tool.
+``sys.last_value``, ``sys.last_type`` and ``sys.last_traceback``. In
+interactive use, this allows one to drop into postmortem debugging with
+any debug tool. One can also manually access the exception information,
+for example::
+
+    >> import sys
+    >> sys.last_traceback.tb_lineno
+    42
+    >> sys.last_value
+    AssertionError('assert result == "ok"',)
 
 Setting a breakpoint / aka ``set_trace()``
 ----------------------------------------------------
diff --git a/testing/test_runner.py b/testing/test_runner.py
index fee1be09b..e62aea9f7 100644
--- a/testing/test_runner.py
+++ b/testing/test_runner.py
@@ -527,7 +527,10 @@ def test_makereport_getsource(testdir):
     result.stdout.fnmatch_lines(['*else: assert False*'])
 
 
-def test_store_except_info_on_eror(testdir):
+def test_store_except_info_on_eror():
+    """ Test that upon test failure, the exception info is stored on
+    sys.last_traceback and friends.
+    """
     # Simulate item that raises a specific exception
     class ItemThatRaises:
         def runtest(self):