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This coding exercise comes from Upcase, the online learning platform we run. It's part of the Refactoring course and is just one small sample of all the great material available on Upcase, so be sure to visit and check out the rest.
In this exercise, you'll be replacing a long list of parameters with a parameter object. The method in question is #calculate_cost in ShippingCalculator which currently takes up to five parameters. This abstraction pattern leads to cleaner code and helps to naturally group parameters.
Watch the related Weekly Iteration episode.
To start, you'll want to clone and run the setup script for the repo
git clone git@github.com:thoughtbot-upcase-exercises/introduce-parameter-object.git
cd introduce-parameter-object
bin/setup
Replace the list of parameters in ShippingCalculator#calculate_cost with a singular parameter object. The existing test suite will need to be modified to accept one parameter as well, however, no new tests should need to be added as this is the "refactoring" phase of TDD.
When you're finished, ShippingCalculator#calculate_cost should accept just one parameter.
Make sure all tests are passing by running:
rake
Check out the featured solution branch to see the approach we recommend for this exercise.
If you find yourself stuck, be sure to check out the associated Upcase Forum discussion for this exercise to see what other folks have said.
When you've finished the exercise, head on back to the Refactoring course to find the next exercise, or explore any of the other great content on Upcase.
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