pry(2)> Phoenix.ConnTest.post conn, "/customers", post: attributes
** (ArgumentError) cannot invoke @/1 outside module
     (elixir) lib/kernel.ex:3960: Kernel.assert_module_scope/3
     (elixir) expanding macro: Kernel.@/1
              test/controllers/customers_controller_test.exs:2: (file)
    (phoenix) expanding macro: Phoenix.ConnTest.post/3
              test/controllers/customers_controller_test.exs:2: (file)

pry(1)> post conn(), "/customers", [username: "john", password: "doe"]
** (ArgumentError) cannot invoke @/1 outside module
     (elixir) lib/kernel.ex:3960: Kernel.assert_module_scope/3
     (elixir) expanding macro: Kernel.@/1
              test/controllers/customers_controller_test.exs:1: (file)
    (phoenix) expanding macro: Phoenix.ConnTest.post/3
              test/controllers/customers_controller_test.exs:1: (file)