Failure/Error: expect(json['title']).to eq('Learn Elm')

[akhmadodi]

Hi,
I got this error when run bundle exec rspec

Failures:

1. Todos API POST /todos when the request is valid creates a todo
   Failure/Error: expect(json['title']).to eq('Learn Elm')

   NoMethodError:
   undefined method `[]' for nil:NilClass

Finished in 1.1 seconds (files took 3.14 seconds to load)
18 examples, 1 failure

Failed examples:

rspec ./spec/requests/todos_spec.rb:60 # Todos API POST /todos when the request is valid creates a todo

Could you please help me
Thanks