Use unittest discover instead of nose.core (#810)

etstool.py

@@ -196,12 +196,17 @@ def test(runtime, toolkit, environment):
     parameters = get_parameters(runtime, toolkit, environment)
     environ = environment_vars.get(toolkit, {}).copy()
     environ['PYTHONUNBUFFERED'] = "1"
+
+    if toolkit == "wx":
+        environ["EXCLUDE_TESTS"] = "qt"
+    elif toolkit in {"pyqt", "pyqt5", "pyside", "pyside2"}:
+        environ["EXCLUDE_TESTS"] = "wx"
+    else:
+        environ["EXCLUDE_TESTS"] = "(wx|qt)"
+
     commands = [
-        "edm run -e {environment} -- coverage run -p -m nose.core -v traitsui.tests --nologcapture"]
-    # extra tests for qt
-    if toolkit in {'pyqt', 'pyside', 'pyqt5'}:
-        commands.append(
-            "edm run -e {environment} -- coverage run -p -m nose.core -v traitsui.qt4.tests --nologcapture")
+        "edm run -e {environment} -- coverage run -p -m unittest discover -v traitsui"
+    ]
 
     # We run in a tempdir to avoid accidentally picking up wrong traitsui
     # code from a local dir.  We need to ensure a good .coveragerc is in

traitsui/__init__.py

@@ -29,3 +29,47 @@
     "pyside": ["pyside>=1.2", "pygments"],
     "demo": ["configobj", "docutils"],
 }
+
+
+# ============================= Test Loader ==================================
+def load_tests(loader, standard_tests, pattern):
+    """ Custom test loading function that enables test filtering using regex
+    exclusion pattern.
+
+    Parameters
+    ----------
+    loader : unittest.TestLoader
+        The instance of test loader
+    standard_tests : unittest.TestSuite
+        Tests that would be loaded by default from this module (no tests)
+    pattern : str
+        An inclusion pattern used to match test files (test*.py default)
+
+    Returns
+    -------
+    filtered_package_tests : unittest.TestSuite
+        TestSuite representing all package tests that did not match specified
+        exclusion pattern.
+    """
+    from os import environ
+    from os.path import dirname
+    from traitsui.tests._tools import filter_tests
+    from unittest import TestSuite
+
+    # Make sure the right toolkit is up and running before importing tests
+    from traitsui.toolkit import toolkit
+    toolkit()
+
+    this_dir = dirname(__file__)
+    package_tests = loader.discover(start_dir=this_dir, pattern=pattern)
+
+    exclusion_pattern = environ.get("EXCLUDE_TESTS", None)
+    if exclusion_pattern is None:
+        return package_tests
+
+    filtered_package_tests = TestSuite()
+    for test_suite in package_tests:
+        filtered_test_suite = filter_tests(test_suite, exclusion_pattern)
+        filtered_package_tests.addTest(filtered_test_suite)
+
+    return filtered_package_tests

traitsui/tests/_tools.py

@@ -14,11 +14,12 @@
 # ------------------------------------------------------------------------------
 
 
+import re
 import sys
 import traceback
 from functools import partial
 from contextlib import contextmanager
-from unittest import skipIf
+from unittest import skipIf, TestSuite
 
 from pyface.toolkit import toolkit_object
 from traits.etsconfig.api import ETSConfig
@@ -113,6 +114,23 @@ def wrapped(*args, **kwargs):
     return wrapped
 
 
+def filter_tests(test_suite, exclusion_pattern):
+    filtered_test_suite = TestSuite()
+    for item in test_suite:
+        if isinstance(item, TestSuite):
+            filtered = filter_tests(item, exclusion_pattern)
+            filtered_test_suite.addTest(filtered)
+        else:
+            match = re.search(exclusion_pattern, item.id())
+            if match is not None:
+                skip_msg = "Test excluded via pattern '{}'".format(
+                    exclusion_pattern
+                )
+                setattr(item, 'setUp', lambda: item.skipTest(skip_msg))
+            filtered_test_suite.addTest(item)
+    return filtered_test_suite
+
+
 # ######### Utility tools to test on both qt4 and wx