Showing microposts:  A failing test for showing microposts on the user show page

Note we won't show microposts on a separate micropost index page
Showing microposts: Adding microposts to the user show page

Techniques:
1. We use '<%= will_paginate @microposts %>' comparing to '<%= will_paginate %>' in the user index page
This is because the user index page is in the context of the UsersController, 'will_paginate' assumes the existence of an instance variable called @users.
In present case, since we are still in the Users controller but want to paginate microposts instead, we pass an explicit @microposts variable to will_paginate. Of course, this means that we will have to define such a variable in the user show action.
2. The use of ordered list tag <ol>
Showing microposts: A partial for showing a single micropost

Techniques:
Use of 'time_ago_in_words' helper method for a text like 'Posted 3 minutes ago'

Note the tests are still failing. The error message is
     Failure/Error: before { visit user_path(user) }
     ActionView::Template::Error:
       'nil' is not an ActiveModel-compatible object. It must implement :to_partial_path.
Because we have not defined instance variable @microposts in the UsersController, thus it doesn't know where to find the partial when it sees '<%= render @microposts %>'
Showing microposts: Adding an @microposts instance variable to the user show action

Now all tests are green
Sample microposts:  Adding microposts to the sample data

Remember to run commands:
$ bundle exec rake db:reset
$ bundle exec rake db:populate
$ bundle exec rake test:prepare

Techniques:
1. We create sample microposts for only the first 6 users in database, by using
User.all(limit: 6)
2. We use helper method Faker::Lorem.sentence to generate mockup text