Shift Cipher challenge

Your Goal

Your challenge is to complete a shift cipher challenge that can encode and decode simple phrases. You will know that your have completed the challenge when all tests complete successfully.

What is a shift cipher?

Shift ciphers are also called Caesar ciphers as they were used by Julius Caesar to scramble his messages to military personnel, so that they were purposefully unintelligible to any unintended reader.

Using a shift cipher is a simple and well-known (albeit usually insecure!) encryption technique, and a suitable topic for the focus of our challenge. In a simple shift cipher, a given input phrase is shifted by a certain number of characters so that it is no longer legible.

When using a shift of 1, each letter in the input text will be modified to the next letter. For example, we could encode:

foobar -> gppcbs

To decode, we can simply reverse the shift:

gppcbs -> foobar

When using a shift of 10:

Encode: foobar -> pyylkb

Decode: pyylkb -> foobar

Our implementation of the shift cipher is a simple one:

For encoding, the input text should be shifted by n characters, with a default shift of 1
For decoding, encoded text should be shifted back and return the original input text.
When a shift causes a letter to pass the end of the alphabet, it should wrap to the beginning. For example, z shifted by 1 should become a.

We have provided you with a Cipher class with two class methods: encode and decode. Both methods take two arguments: input and distance. You will notice that the tests do not always specify distance, so a default may be necessary.

To Download

Fork this repository to your own account or download it as a zip and extract the files.

To Run

Open a terminal window and navigate to the challenge directory.
Run gem install minitest.
Run ruby cipher_test.rb to test the challenge.
On the first run, Minitest should output the following:

n runs, 0 assertions, 0 failures, 0 errors, n skips

To Complete

The project contains two files: cipher_test.rb and cipher.rb. You will need to modify both of these files.
Any code changes should be placed in cipher.rb. We have created a class in this file for you to build on.
skip statements in cipher_test.rb should be commented out as you begin to test your code.
You are encouraged to make this an iterative TDD process: comment out one skip statement and run the tests to ensure they pass. Then proceed to the commenting out the next skip statement and repeat the process.
The challenge is considered complete once all skip statements are commented out and all tests pass (0 failures, 0 errors, 0 skips).

To Submit

If you forked the repository, ensure your repo is public, your changes are committed and pushed, and send us a link to your repository via email.
If you downloaded the repository as a zip file, zip your changes and send them to us via an email attachment.

Troubleshooting

Ensure you have ruby installed (ruby -v)
Ensure you have minitest installed (gem install minitest)
Ensure you are in the challenge directory

About Us

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Learn more: https://www.cyndx.com

Attribution

Simplified and adapted from the Exercism (https://exercism.io/) cipher exercise.

ShawnCodes/simple-cipher