Add a syntax error that our tests miss

Task

Deliberately introduce a syntax error into our code that our tests are unable to detect to illustrate the limitations of our controller tests.

Steps

Edit the other controller file, app/controllers/user_limericks_controller.rb, to add a syntax error into that controller’s index method as follows.

class UserLimericksController < ApplicationController

  before_action :authenticate_user!

  def index
    @user = User.find(params[:user_id])
    @limericks = @user.limericks.reverse_order
    renxxxxxxder :index
  end

end

Note that, similar to the earlier example, the call to render is now an invalid call to an undefined method renxxxxxxder.
Run all tests to check for errors.

rails test -v

Inspect the output, which should look like this:

Running 1 tests in a single process (parallelization threshold is 50)
Run options: -v --seed 389

# Running:

LimericksControllerTest#test_should_get_index = 2.11 s = .

Finished in 2.112802s, 0.4733 runs/s, 0.9466 assertions/s.
1 runs, 2 assertions, 0 failures, 0 errors, 0 skips

Note that the test did not detect the obvious syntax error! How can this be?
- Answer: If you accidentally add a syntax error into a Ruby script, the error will not be revealed unless the script file with the error is loaded.
- Rails uses “lazy loading”, which means that script files are loaded only when they are used.
- In the case above, the file with the syntax error was never used by our test case, and therefore, the file was never loaded.
- Thus, thorough automated testing (which ensures that all code files are loaded and tested) is particularly important for discovering these sorts of errors.
Before moving on, correct the above bug.

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