Display traceback from Import errors using pytest's short representation

Also omit pytest's own modules and internal libraries (py and pluggy) in low verbosity

Fix #1976

Author: nicoddemus

_pytest/python.py

@@ -22,11 +22,16 @@
     getlocation, enum,
 )
 
-cutdir2 = py.path.local(_pytest.__file__).dirpath()
 cutdir1 = py.path.local(pluggy.__file__.rstrip("oc"))
+cutdir2 = py.path.local(_pytest.__file__).dirpath()
+cutdir3 = py.path.local(py.__file__).dirpath()
 
 
 def filter_traceback(entry):
+    """Return True if a TracebackEntry instance should be removed from tracebacks:
+    * dynamically generated code (no code to show up for it);
+    * internal traceback from pytest or its internal libraries, py and pluggy.
+    """
     # entry.path might sometimes return a str object when the entry
     # points to dynamically generated code
     # see https://bitbucket.org/pytest-dev/py/issues/71
@@ -37,7 +42,7 @@ def filter_traceback(entry):
     # entry.path might point to an inexisting file, in which case it will
     # alsso return a str object. see #1133
     p = py.path.local(entry.path)
-    return p != cutdir1 and not p.relto(cutdir2)
+    return p != cutdir1 and not p.relto(cutdir2) and not p.relto(cutdir3)
 
 
 
@@ -424,14 +429,16 @@ def _importtestmodule(self):
                  % e.args
             )
         except ImportError:
-            import traceback
-            stream = py.io.TextIO()
-            traceback.print_exc(file=stream)
-            formatted_tb = stream.getvalue()
+            from _pytest._code.code import ExceptionInfo
+            exc_info = ExceptionInfo()
+            if self.config.getoption('verbose') < 2:
+                exc_info.traceback = exc_info.traceback.filter(filter_traceback)
+            exc_repr = exc_info.getrepr(style='short') if exc_info.traceback else exc_info.exconly()
+            formatted_tb = py._builtin._totext(exc_repr)
             raise self.CollectError(
                 "ImportError while importing test module '{fspath}'.\n"
                 "Hint: make sure your test modules/packages have valid Python names.\n"
-                "Original traceback:\n"
+                "Traceback:\n"
                 "{traceback}".format(fspath=self.fspath, traceback=formatted_tb)
             )
         except _pytest.runner.Skipped as e:

testing/python/collect.py

@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+import os
 import sys
 from textwrap import dedent
 
@@ -71,8 +72,12 @@ def test_invalid_test_module_name(self, testdir):
             "Hint: make sure your test modules/packages have valid Python names.",
         ])
 
-    def test_show_full_traceback_import_error(self, testdir):
-        """Import errors when collecting modules should display the full traceback (#1976)."""
+    @pytest.mark.parametrize('verbose', [0, 1, 2])
+    def test_show_traceback_import_error(self, testdir, verbose):
+        """Import errors when collecting modules should display the traceback (#1976).
+
+        With low verbosity we omit pytest and internal modules, otherwise show all traceback entries.
+        """
         testdir.makepyfile(
             foo_traceback_import_error="""
                from bar_traceback_import_error import NOT_AVAILABLE
@@ -82,15 +87,23 @@ def test_show_full_traceback_import_error(self, testdir):
         testdir.makepyfile("""
                import foo_traceback_import_error
         """)
-        result = testdir.runpytest()
+        args = ('-v',) * verbose
+        result = testdir.runpytest(*args)
         result.stdout.fnmatch_lines([
             "ImportError while importing test module*",
-            "Original traceback:",
+            "Traceback:",
             "*from bar_traceback_import_error import NOT_AVAILABLE",
             "*cannot import name *NOT_AVAILABLE*",
         ])
         assert result.ret == 2
 
+        stdout = result.stdout.str()
+        for name in ('_pytest', os.path.join('py', '_path')):
+            if verbose == 2:
+                assert name in stdout
+            else:
+                assert name not in stdout
+
 
 class TestClass:
     def test_class_with_init_warning(self, testdir):