Use random.seed for deterministic doctest outputs

patterns/other/blackboard.py

@@ -90,30 +90,37 @@ def contribute(self):
         self.blackboard.common_state['progress'] += random.randint(10, 100)
 
 
+def main():
+    """
+    >>> blackboard = Blackboard()
+    >>> blackboard.add_expert(Student(blackboard))
+    >>> blackboard.add_expert(Scientist(blackboard))
+    >>> blackboard.add_expert(Professor(blackboard))
+
+    >>> c = Controller(blackboard)
+    >>> contributions = c.run_loop()
+
+    >>> from pprint import pprint
+    >>> pprint(contributions)
+    ['Student',
+     'Student',
+     'Student',
+     'Student',
+     'Scientist',
+     'Student',
+     'Student',
+     'Student',
+     'Scientist',
+     'Student',
+     'Scientist',
+     'Student',
+     'Student',
+     'Scientist',
+     'Professor']
+    """
+
+
 if __name__ == '__main__':
-    blackboard = Blackboard()
-
-    blackboard.add_expert(Student(blackboard))
-    blackboard.add_expert(Scientist(blackboard))
-    blackboard.add_expert(Professor(blackboard))
-
-    c = Controller(blackboard)
-    contributions = c.run_loop()
-
-    from pprint import pprint
-
-    pprint(contributions)
-
-### OUTPUT ###
-# ['Student',
-#  'Student',
-#  'Scientist',
-#  'Student',
-#  'Scientist',
-#  'Student',
-#  'Scientist',
-#  'Student',
-#  'Scientist',
-#  'Student',
-#  'Scientist',
-#  'Professor']
+    random.seed(1234)  # for deterministic doctest outputs
+    import doctest
+    doctest.testmod()

requirements-dev.txt

@@ -3,3 +3,4 @@
 pytest~=4.3.0
 pytest-cov~=2.6.0
 flake8~=3.7.0
+pytest-randomly~=3.1.0

tox.ini

@@ -9,8 +9,10 @@ deps =
     -r requirements-dev.txt
 commands =
     flake8 patterns/
-    pytest --doctest-modules patterns/
-    pytest -s -vv --cov={envsitepackagesdir}/patterns --log-level=INFO tests/
+    ; `randomly-seed` option from `pytest-randomly` helps with deterministic outputs for examples like `other/blackboard.py`
+    pytest --randomly-seed=1234 --doctest-modules patterns/
+    ; `-p no:randomly` turns off `randomly` plugin for unit tests
+    pytest -s -vv --cov={envsitepackagesdir}/patterns --log-level=INFO -p no:randomly tests/
 
 
 [testenv:cov-report]