Display full traceback from Import errors when collecting test modules

Fix pytest-dev#1976

CHANGELOG.rst

@@ -3,13 +3,20 @@
 
 *
 
-*
+* Import errors when collecting test modules now display the full traceback (`#1976`_).
+ Thanks `@cwitty`_ for the report and `@nicoddemus`_ for the PR.
 
 *
 
 *
 
 
+.. _@cwitty: https://github.com/cwitty
+
+.. _#1976: https://github.com/pytest-dev/pytest/issues/1976
+
+
+
 3.0.3
 =====
 

_pytest/python.py

@@ -424,12 +424,15 @@ def _importtestmodule(self):
  % e.args
  )
  except ImportError:
- exc_class, exc, _ = sys.exc_info()
+ import traceback
+ stream = py.io.TextIO()
+ traceback.print_exc(file=stream)
+ formatted_tb = stream.getvalue()
  raise self.CollectError(
- "ImportError while importing test module '%s'.\n"
- "Original error message:\n'%s'\n"
- "Make sure your test modules/packages have valid Python names."
- % (self.fspath, exc or exc_class)
+ "ImportError while importing test module '{fspath}'.\n"
+ "Hint: make sure your test modules/packages have valid Python names.\n"
+ "Original traceback:\n"
+ "{traceback}".format(fspath=self.fspath, traceback=formatted_tb)
  )
  except _pytest.runner.Skipped as e:
  if e.allow_module_level:

testing/acceptance_test.py

@@ -120,7 +120,7 @@ def test_this():
  result.stdout.fnmatch_lines([
  #XXX on jython this fails: "> import import_fails",
  "ImportError while importing test module*",
- "'No module named *does_not_work*",
+ "*No module named *does_not_work*",
  ])
  assert result.ret == 2
 

testing/python/collect.py

@@ -68,9 +68,29 @@ def test_invalid_test_module_name(self, testdir):
  result = testdir.runpytest("-rw")
  result.stdout.fnmatch_lines([
  "ImportError while importing test module*test_one.part1*",
- "Make sure your test modules/packages have valid Python names.",
+ "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)."""
+ testdir.makepyfile(
+ foo_traceback_import_error="""
+ from bar_traceback_import_error import NOT_AVAILABLE
+ """,
+ bar_traceback_import_error="",
+ )
+ testdir.makepyfile("""
+ import foo_traceback_import_error
+ """)
+ result = testdir.runpytest()
+ result.stdout.fnmatch_lines([
+ "ImportError while importing test module*",
+ "Original traceback:",
+ "*from bar_traceback_import_error import NOT_AVAILABLE",
+ "*cannot import name *NOT_AVAILABLE*",
+ ])
+ assert result.ret == 2
+
 
 class TestClass:
  def test_class_with_init_warning(self, testdir):

testing/test_collection.py

@@ -172,17 +172,6 @@ def pytest_collect_directory(self, path, parent):
  assert "world" in wascalled
 
 class TestPrunetraceback:
- def test_collection_error(self, testdir):
- p = testdir.makepyfile("""
- import not_exists
- """)
- result = testdir.runpytest(p)
- assert "__import__" not in result.stdout.str(), "too long traceback"
- result.stdout.fnmatch_lines([
- "*ERROR collecting*",
- "ImportError while importing test module*",
- "'No module named *not_exists*",
- ])
 
  def test_custom_repr_failure(self, testdir):
  p = testdir.makepyfile("""

testing/test_terminal.py

@@ -667,7 +667,7 @@ def test_collect_fail(self, testdir, option):
  result = testdir.runpytest(*option.args)
  result.stdout.fnmatch_lines([
  "ImportError while importing*",
- "'No module named *xyz*",
+ "*No module named *xyz*",
  "*1 error*",
  ])