switch test runner from nose to pytest

.travis.yml

@@ -63,8 +63,8 @@ install:
   - pip install flake8 flake8-import-order
   - pip install tox         # tox 3.11.0 has requirement virtualenv>=14.0.0
   - pip install virtualenv  # virtualenv>=14.0.0 has dropped Python 3.2 support (and pypy3 is based on py32)
-  # Install the tox venv.
+  # Install the tox venv (we make pytest avoid running the test by giving a bad pattern)
-  - tox -e $(echo py$TRAVIS_PYTHON_VERSION-mg$PYMONGO | tr -d . | sed -e 's/pypypy/pypy/') -- -e test
+  - tox -e $(echo py$TRAVIS_PYTHON_VERSION-mg$PYMONGO | tr -d . | sed -e 's/pypypy/pypy/') -- -a "-k=test_ci_placeholder"
   # Install black for Python v3.7 only.
   - if [[ $TRAVIS_PYTHON_VERSION == '3.7' ]]; then pip install black; fi
 
@@ -76,7 +76,7 @@ before_script:
   - mongo --eval 'db.version();'    # Make sure mongo is awake
 
 script:
-  - tox -e $(echo py$TRAVIS_PYTHON_VERSION-mg$PYMONGO | tr -d . | sed -e 's/pypypy/pypy/') -- --with-coverage
+  - tox -e $(echo py$TRAVIS_PYTHON_VERSION-mg$PYMONGO | tr -d . | sed -e 's/pypypy/pypy/') #-- --with-coverage
 
 # For now only submit coveralls for Python v2.7. Python v3.x currently shows
 # 0% coverage. That's caused by 'use_2to3', which builds the py3-compatible

README.rst

@@ -116,7 +116,8 @@ Some simple examples of what MongoEngine code looks like:
 Tests
 =====
 To run the test suite, ensure you are running a local instance of MongoDB on
-the standard port and have ``nose`` installed. Then, run ``python setup.py nosetests``.
+the standard port and have ``pytest`` installed. Then, run ``python setup.py test``
+or simply ``pytest``.
 
 To run the test suite on every supported Python and PyMongo version, you can
 use ``tox``. You'll need to make sure you have each supported Python version
@@ -129,16 +130,14 @@ installed in your environment and then:
     # Run the test suites
     $ tox
 
-If you wish to run a subset of tests, use the nosetests convention:
+If you wish to run a subset of tests, use the pytest convention:
 
 .. code-block:: shell
 
     # Run all the tests in a particular test file
-    $ python setup.py nosetests --tests tests/fields/fields.py
+    $ pytest tests/fields/test_fields.py
     # Run only particular test class in that file
-    $ python setup.py nosetests --tests tests/fields/fields.py:FieldTest
+    $ pytest tests/fields/test_fields.py::TestField
-    # Use the -s option if you want to print some debug statements or use pdb
-    $ python setup.py nosetests --tests tests/fields/fields.py:FieldTest -s
 
 Community
 =========

setup.cfg

@@ -1,11 +1,10 @@
-[nosetests]
-verbosity=2
-detailed-errors=1
-#tests=tests
-cover-package=mongoengine
-
 [flake8]
 ignore=E501,F401,F403,F405,I201,I202,W504, W605, W503
 exclude=build,dist,docs,venv,venv3,.tox,.eggs,tests
 max-complexity=47
 application-import-names=mongoengine,tests
+
+[tool:pytest]
+# Limits the discovery to tests directory
+# avoids that it runs for instance the benchmark
+testpaths = tests

setup.py

@@ -1,6 +1,9 @@
 import os
 import sys
+
+from pkg_resources import normalize_path
 from setuptools import find_packages, setup
+from setuptools.command.test import test as TestCommand
 
 # Hack to silence atexit traceback in newer python versions
 try:
@@ -24,6 +27,65 @@ def get_version(version_tuple):
     return ".".join(map(str, version_tuple))
 
 
+class PyTest(TestCommand):
+    """Will force pytest to search for tests inside the build directory
+    for 2to3 converted code (used by tox), instead of the current directory.
+    Required as long as we need 2to3
+
+    Known Limitation: https://tox.readthedocs.io/en/latest/example/pytest.html#known-issues-and-limitations
+    Source: https://www.hackzine.org/python-testing-with-pytest-and-2to3-plus-tox-and-travis-ci.html
+    """
+
+    # https://pytest.readthedocs.io/en/2.7.3/goodpractises.html#integration-with-setuptools-test-commands
+    # Allows to provide pytest command arguments through the test runner command `python setup.py test`
+    # e.g: `python setup.py test -a "-k=test"`
+    user_options = [("pytest-args=", "a", "Arguments to pass to py.test")]
+
+    def initialize_options(self):
+        TestCommand.initialize_options(self)
+        self.pytest_args = ""
+
+    def finalize_options(self):
+        TestCommand.finalize_options(self)
+        self.test_args = ["tests"]
+        self.test_suite = True
+
+    def run_tests(self):
+        # import here, cause outside the eggs aren't loaded
+        from pkg_resources import _namespace_packages
+        import pytest
+
+        # Purge modules under test from sys.modules. The test loader will
+        # re-import them from the build location. Required when 2to3 is used
+        # with namespace packages.
+        if sys.version_info >= (3,) and getattr(self.distribution, "use_2to3", False):
+            print("Hack for 2to3", self.test_args)
+            module = self.test_args[-1].split(".")[0]
+            if module in _namespace_packages:
+                del_modules = []
+                if module in sys.modules:
+                    del_modules.append(module)
+                module += "."
+                for name in sys.modules:
+                    if name.startswith(module):
+                        del_modules.append(name)
+                map(sys.modules.__delitem__, del_modules)
+
+            # Run on the build directory for 2to3-built code
+            # This will prevent the old 2.x code from being found
+            # by py.test discovery mechanism, that apparently
+            # ignores sys.path..
+            ei_cmd = self.get_finalized_command("egg_info")
+            self.test_args = [normalize_path(ei_cmd.egg_base)]
+
+        print(self.test_args, self.pytest_args)
+        cmd_args = self.test_args + ([self.pytest_args] if self.pytest_args else [])
+        print(cmd_args)
+        errno = pytest.main(cmd_args)
+
+        sys.exit(errno)
+
+
 # Dirty hack to get version number from monogengine/__init__.py - we can't
 # import it as it depends on PyMongo and PyMongo isn't installed until this
 # file is read
@@ -51,7 +113,7 @@ CLASSIFIERS = [
 
 extra_opts = {
     "packages": find_packages(exclude=["tests", "tests.*"]),
-    "tests_require": ["nose", "coverage==4.2", "blinker", "Pillow>=2.0.0"],
+    "tests_require": ["pytest<5.0", "coverage==4.2", "blinker", "Pillow>=2.0.0"],
 }
 if sys.version_info[0] == 3:
     extra_opts["use_2to3"] = True
@@ -79,6 +141,6 @@ setup(
     platforms=["any"],
     classifiers=CLASSIFIERS,
     install_requires=["pymongo>=3.4", "six"],
-    test_suite="nose.collector",
+    cmdclass={"test": PyTest},
     **extra_opts
 )

tests/test_ci.py

@@ -0,0 +1,9 @@
+def test_ci_placeholder():
+    # This empty test is used within the CI to
+    # setup the tox venv without running the test suite
+    # if we simply skip all test with pytest -k=wrong_pattern
+    # pytest command would return with exit_code=5 (i.e "no tests run")
+    # making travis fail
+    # this empty test is the recommended way to handle this
+    # as described in https://github.com/pytest-dev/pytest/issues/2393
+    pass

tox.ini

@@ -3,7 +3,7 @@ envlist = {py27,py35,pypy,pypy3}-{mg34,mg36}
 
 [testenv]
 commands =
-    python setup.py nosetests {posargs}
+    python setup.py test {posargs}
 deps =
     nose
     mg34: pymongo>=3.4,<3.5