Update Mediator pattern

gyermolenko · gyermolenko · commit ef809fef611e · 2019-02-07T15:11:27.000+02:00
diff --git a/patterns/behavioral/mediator.py b/patterns/behavioral/mediator.py
@@ -2,150 +2,53 @@
 # -*- coding: utf-8 -*-
 
 """
-http://web.archive.org/web/20120309135549/http://dpip.testingperspective.com/?p=28
+https://www.djangospin.com/design-patterns-python/mediator/
+
+Objects in a system communicate through a Mediator instead of directly with each other.
+This reduces the dependencies between communicating objects, thereby reducing coupling.
 
 *TL;DR80
 Encapsulates how a set of objects interact.
 """
 
-import random
-import time
-
-
-class TC:
-    def __init__(self):
-        self._tm = None
-        self._bProblem = 0
-
-    def setup(self):
-        print("Setting up the Test")
-        time.sleep(0.1)
-        self._tm.prepareReporting()
-
-    def execute(self):
-        if not self._bProblem:
-            print("Executing the test")
-            time.sleep(0.1)
-        else:
-            print("Problem in setup. Test not executed.")
-
-    def tearDown(self):
-        if not self._bProblem:
-            print("Tearing down")
-            time.sleep(0.1)
-            self._tm.publishReport()
-        else:
-            print("Test not executed. No tear down required.")
-
-    def setTM(self, tm):
-        self._tm = tm
-
-    def setProblem(self, value):
-        self._bProblem = value
-
-
-class Reporter:
-    def __init__(self):
-        self._tm = None
 
-    def prepare(self):
-        print("Reporter Class is preparing to report the results")
-        time.sleep(0.1)
+class ChatRoom(object):
+    """Mediator class"""
 
-    def report(self):
-        print("Reporting the results of Test")
-        time.sleep(0.1)
+    def display_message(self, user, message):
+        print("[{} says]: {}".format(user, message))
 
-    def setTM(self, tm):
-        self._tm = tm
 
+class User(object):
+    """A class whose instances want to interact with each other"""
 
-class DB:
-    def __init__(self):
-        self._tm = None
+    def __init__(self, name):
+        self.name = name
+        self.chat_room = ChatRoom()
 
-    def insert(self):
-        print("Inserting the execution begin status in the Database")
-        time.sleep(0.1)
-        # Following code is to simulate a communication from DB to TC
-        if random.randrange(1, 4) == 3:
-            return -1
+    def say(self, message):
+        self.chat_room.display_message(self, message)
 
-    def update(self):
-        print("Updating the test results in Database")
-        time.sleep(0.1)
-
-    def setTM(self, tm):
-        self._tm = tm
-
-
-class TestManager:
-    def __init__(self):
-        self._reporter = None
-        self._db = None
-        self._tc = None
-
-    def prepareReporting(self):
-        rvalue = self._db.insert()
-        if rvalue == -1:
-            self._tc.setProblem(1)
-            self._reporter.prepare()
-
-    def setReporter(self, reporter):
-        self._reporter = reporter
-
-    def setDB(self, db):
-        self._db = db
-
-    def publishReport(self):
-        self._db.update()
-        self._reporter.report()
-
-    def setTC(self, tc):
-        self._tc = tc
+    def __str__(self):
+        return self.name
 
 
 def main():
-    reporter = Reporter()
-    db = DB()
-    tm = TestManager()
-    tm.setReporter(reporter)
-    tm.setDB(db)
-    reporter.setTM(tm)
-    db.setTM(tm)
-    # For simplification we are looping on the same test.
-    # Practically, it could be about various unique test classes and their
-    # objects
-    for i in range(3):
-        tc = TC()
-        tc.setTM(tm)
-        tm.setTC(tc)
-        tc.setup()
-        tc.execute()
-        tc.tearDown()
+    molly = User('Molly')
+    mark = User('Mark')
+    ethan = User('Ethan')
+
+    molly.say("Hi Team! Meeting at 3 PM today.")
+    mark.say("Roger that!")
+    ethan.say("Alright.")
 
 
 if __name__ == '__main__':
     main()
 
 
 OUTPUT = """
-Setting up the Test
-Inserting the execution begin status in the Database
-Executing the test
-Tearing down
-Updating the test results in Database
-Reporting the results of Test
-Setting up the Test
-Inserting the execution begin status in the Database
-Executing the test
-Tearing down
-Updating the test results in Database
-Reporting the results of Test
-Setting up the Test
-Inserting the execution begin status in the Database
-Executing the test
-Tearing down
-Updating the test results in Database
-Reporting the results of Test
-"""
+[Molly says]: Hi Team! Meeting at 3 PM today.
+[Mark says]: Roger that!
+[Ethan says]: Alright.
+"""  # noqa
diff --git a/tests/test_outputs.py b/tests/test_outputs.py
@@ -18,6 +18,8 @@
 from patterns.behavioral.command import OUTPUT as command_output
 from patterns.behavioral.iterator import main as iterator_main
 from patterns.behavioral.iterator import OUTPUT as iterator_output
+from patterns.behavioral.mediator import main as mediator_main
+from patterns.behavioral.mediator import OUTPUT as mediator_output
 from patterns.behavioral.observer import main as observer_main
 from patterns.behavioral.observer import OUTPUT as observer_output
 from patterns.behavioral.publish_subscribe import main as publish_subscribe_main
@@ -42,6 +44,7 @@
     (chaining_method_main, chaining_method_output),
     (command_main, command_output),
     (iterator_main, iterator_output),
+    (mediator_main, mediator_output),
     (observer_main, observer_output),
     (publish_subscribe_main, publish_subscribe_output),
     (specification_main, specification_output),
