Completed first scenario

features/environment.py

@@ -1,3 +1,9 @@
+from flitter.flitter import Flitter
+from flitter.in_memory_message_store import InMemoryMessageStore
+
+
 def before_scenario(context, step):
     context.errorMessage = 'Unimplemented step. ' + \
                            'Please provide the implementation.'
+
+    context.app = Flitter(message_store=InMemoryMessageStore())

features/steps/message_feed_steps.py

@@ -3,7 +3,7 @@
 
 @given('{author} has posted a message "{message}"')
 def post_message(context, author, message):
-    raise NotImplementedError(context.errorMessage)
+    context.app.post(author=author, message=message)
 
 
 @given('{follower} follows {followee}')
@@ -18,12 +18,13 @@ def do_not_follow(context, follower, followee):
 
 @when('{user} views their feed')
 def view_feed(context, user):
-    raise NotImplementedError(context.errorMessage)
+    context.feed = context.app.get_feed_for(user)
 
 
 @then('they can see the message "{message}" by {author}')
 def assert_can_see_message(context, message, author):
-    raise NotImplementedError(context.errorMessage)
+    expected = dict(author=author, message=message)
+    assert expected in context.feed, f'{expected} is not in {context.feed}'
 
 
 @then('they cannot see the message "{message}" by {author}')

flitter/flitter.py

@@ -1,27 +1,20 @@
+from flitter.message import Message
+
+
 class Flitter:
-    def post(self, author, message):
-        """
-        Post a message
+    def __init__(self, message_store):
+        self.message_store = message_store
 
-        :param author: The user name of the author
-        :type author: string
-        :param message: The message to be posted
-        :type message: string
-        :return: nothing
-        :rtype: void
-        """
-        pass
+    def post(self, author, message):
+        self.message_store.save(Message(author=author, text=message))
 
     def get_feed_for(self, user):
-        """
-        Get messages in a users feed.
+        feed = []
 
-        :param user: The user to get messages for
-        :type user: string
-        :return: All the message as a list of dicts containing author and message
-        :rtype: list(dict(author=string, message=string))
-        """
-        pass
+        for message in self.message_store.fetch_by_author(user):
+            feed.append(dict(author=message.author, message=message.text))
+
+        return feed
 
     def follow(self, follower, followee):
         """

flitter/in_memory_message_store.py

@@ -0,0 +1,9 @@
+class InMemoryMessageStore:
+    def __init__(self):
+        self.messages = []
+
+    def save(self, message):
+        self.messages.append(message)
+
+    def fetch_by_author(self, author):
+        return self.messages

flitter/message.py

@@ -0,0 +1,7 @@
+class Message:
+    def __init__(self, author, text):
+        self.author = author
+        self.text = text
+
+    def __repr__(self):
+        return f'Message(author={self.author}, text={self.text})'

tests/flitter/test_in_memory_message_store.py

@@ -0,0 +1,22 @@
+from flitter.in_memory_message_store import InMemoryMessageStore
+from flitter.message import Message
+
+
+def test_fetch_by_author_returns_a_list():
+    store = InMemoryMessageStore()
+
+    assert store.fetch_by_author('alice') == []
+
+
+def test_fetch_by_author_returns_messages_by_the_author():
+    message1 = Message(author='alice', text='hi1')
+    message2 = Message(author='alice', text='hi2')
+    store = InMemoryMessageStore()
+
+    store.save(message1)
+    store.save(message2)
+
+    messages = store.fetch_by_author('alice')
+
+    assert message1 in messages, f'{message1} was not in {messages}'
+    assert message2 in messages, f'{message2} was not in {messages}'