unittest: do not use TestCase.debug() with --pdb

Fixes pytest-dev#5991
Fixes pytest-dev#3823

Ref: pytest-dev/pytest-django#772
Ref: pytest-dev#1890
Ref: pytest-dev/pytest-django#782

- inject wrapped testMethod

- adjust test_trial_error

- add test for `--trace` with unittests

changelog/3823.bugfix.rst

@@ -0,0 +1 @@
+``--trace`` now works with unittests.

changelog/5991.bugfix.rst

@@ -0,0 +1 @@
+Fix interaction with ``--pdb`` and unittests: do not use unittest's ``TestCase.debug()``.

doc/en/unittest.rst

@@ -238,17 +238,6 @@ was executed ahead of the ``test_method``.
 
 .. _pdb-unittest-note:
 
-.. note::
-
-    Running tests from ``unittest.TestCase`` subclasses with ``--pdb`` will
-    disable tearDown and cleanup methods for the case that an Exception
-    occurs. This allows proper post mortem debugging for all applications
-    which have significant logic in their tearDown machinery. However,
-    supporting this feature has the following side effect: If people
-    overwrite ``unittest.TestCase`` ``__call__`` or ``run``, they need to
-    to overwrite ``debug`` in the same way  (this is also true for standard
-    unittest).
-
 .. note::
 
     Due to architectural differences between the two frameworks, setup and

src/_pytest/unittest.py

@@ -1,4 +1,5 @@
 """ discovery and running of std-library "unittest" style tests. """
+import functools
 import sys
 import traceback
 
@@ -187,29 +188,16 @@ def addSuccess(self, testcase):
     def stopTest(self, testcase):
         pass
 
-    def _handle_skip(self):
-        # implements the skipping machinery (see #2137)
-        # analog to pythons Lib/unittest/case.py:run
+    def runtest(self):
         testMethod = getattr(self._testcase, self._testcase._testMethodName)
-        if getattr(self._testcase.__class__, "__unittest_skip__", False) or getattr(
-            testMethod, "__unittest_skip__", False
-        ):
-            # If the class or method was skipped.
-            skip_why = getattr(
-                self._testcase.__class__, "__unittest_skip_why__", ""
-            ) or getattr(testMethod, "__unittest_skip_why__", "")
-            self._testcase._addSkip(self, self._testcase, skip_why)
-            return True
-        return False
 
-    def runtest(self):
-        if self.config.pluginmanager.get_plugin("pdbinvoke") is None:
-            self._testcase(result=self)
-        else:
-            # disables tearDown and cleanups for post mortem debugging (see #1890)
-            if self._handle_skip():
-                return
-            self._testcase.debug()
+        @functools.wraps(testMethod)
+        def wrapped_testMethod(*args, **kwargs):
+            self.ihook.pytest_pyfunc_call(pyfuncitem=self)
+
+        self._testcase._wrapped_testMethod = wrapped_testMethod
+        self._testcase._testMethodName = "_wrapped_testMethod"
+        self._testcase(result=self)
 
     def _prunetraceback(self, excinfo):
         Function._prunetraceback(self, excinfo)

testing/test_pdb.py

@@ -164,20 +164,32 @@ def test_pdb_unittest_postmortem(self, testdir):
         p1 = testdir.makepyfile(
             """
             import unittest
+
+            teardown_called = 0
+
             class Blub(unittest.TestCase):
                 def tearDown(self):
-                    self.filename = None
-                def test_false(self):
+                    global teardown_called
+                    teardown_called += 1
+
+                def test_error(self):
+                    assert teardown_called == 0
                     self.filename = 'debug' + '.me'
                     assert 0
+
+                def test_check(self):
+                    assert teardown_called == 1
         """
         )
-        child = testdir.spawn_pytest("--pdb %s" % p1)
+        child = testdir.spawn_pytest(
+            "--pdb {p1}::Blub::test_error {p1}::Blub::test_check".format(p1=p1)
+        )
         child.expect("Pdb")
-        child.sendline("p self.filename")
-        child.sendeof()
+        child.sendline("p 'filename=' + self.filename")
+        child.expect("'filename=debug.me'")
+        child.sendline("c")
         rest = child.read().decode("utf8")
-        assert "debug.me" in rest
+        assert "= 1 failed, 1 passed in" in rest
         self.flush(child)
 
     def test_pdb_unittest_skip(self, testdir):

testing/test_unittest.py

@@ -537,24 +537,28 @@ def f(_):
         )
         result.stdout.fnmatch_lines(
             [
-                "test_trial_error.py::TC::test_four FAILED",
+                "test_trial_error.py::TC::test_four SKIPPED",
                 "test_trial_error.py::TC::test_four ERROR",
                 "test_trial_error.py::TC::test_one FAILED",
                 "test_trial_error.py::TC::test_three FAILED",
-                "test_trial_error.py::TC::test_two FAILED",
+                "test_trial_error.py::TC::test_two SKIPPED",
+                "test_trial_error.py::TC::test_two ERROR",
                 "*ERRORS*",
                 "*_ ERROR at teardown of TC.test_four _*",
+                "NOTE: Incompatible Exception Representation, displaying natively:",
+                "*DelayedCalls*",
+                "*_ ERROR at teardown of TC.test_two _*",
+                "NOTE: Incompatible Exception Representation, displaying natively:",
                 "*DelayedCalls*",
                 "*= FAILURES =*",
-                "*_ TC.test_four _*",
-                "*NameError*crash*",
+                # "*_ TC.test_four _*",
+                # "*NameError*crash*",
                 "*_ TC.test_one _*",
                 "*NameError*crash*",
                 "*_ TC.test_three _*",
+                "NOTE: Incompatible Exception Representation, displaying natively:",
                 "*DelayedCalls*",
-                "*_ TC.test_two _*",
-                "*NameError*crash*",
-                "*= 4 failed, 1 error in *",
+                "*= 2 failed, 2 skipped, 2 errors in *",
             ]
         )
 
@@ -1096,3 +1100,26 @@ def test_should_not_run(self):
     )
     result = testdir.runpytest()
     result.stdout.fnmatch_lines(["*Exit: pytest_exit called*", "*= no tests ran in *"])
+
+
+def test_trace(testdir):
+    p1 = testdir.makepyfile(
+        """
+        import unittest
+
+        class MyTestCase(unittest.TestCase):
+            def test(self):
+                self.assertEqual('foo', 'foo')
+    """
+    )
+    result = testdir.runpytest("--trace", str(p1))
+    result.stdout.fnmatch_lines(
+        [
+            "self = <test_trace.MyTestCase testMethod=_wrapped_testMethod>",
+            "    def test(self):",
+            ">       self.assertEqual('foo', 'foo')",
+            "test_trace.py:5: ",
+            "* in trace_dispatch",
+        ]
+    )
+    assert result.ret == ExitCode.TESTS_FAILED