feat: Switch from nosetest to pytest (#10177)

* Switch from nosetest to pytest

Fix schedule tests

Collect pytest coverage

Move pytest config into pytest.ini

Move cov to the pytest.ini

* Append coverage for the 2nd run

* Add coverage to all commands

* Coverage only for tests

* Get coverage from 1 place

* Rename classes to be  pytest compatible

* Test coverage for examples and tests

* Max diff to -1

* Explain how to run pytest for the whole project

* Do not append code coverage for the main run

* Do not run coverage on examples

Co-authored-by: bogdan kyryliuk <bogdankyryliuk@dropbox.com>

tests/base_tests.py

@@ -52,9 +52,7 @@ class SupersetTestCase(TestCase):
         "postgresql": "public",
     }
 
-    def __init__(self, *args, **kwargs):
-        super(SupersetTestCase, self).__init__(*args, **kwargs)
-        self.maxDiff = None
+    maxDiff = -1
 
     def create_app(self):
         return app