Started working on the rotational-cipher challenge

Author: sinanata

rotational-cipher/.exercism/metadata.json

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+{"track":"python","exercise":"rotational-cipher","id":"0fda01dc4249444eb8e43fe516773f34","url":"https://exercism.io/my/solutions/0fda01dc4249444eb8e43fe516773f34","handle":"sinanata","is_requester":true,"auto_approve":false}

rotational-cipher/README.md

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+# Rotational Cipher
+
+Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.
+
+The Caesar cipher is a simple shift cipher that relies on
+transposing all the letters in the alphabet using an integer key
+between `0` and `26`. Using a key of `0` or `26` will always yield
+the same output due to modular arithmetic. The letter is shifted
+for as many values as the value of the key.
+
+The general notation for rotational ciphers is `ROT + <key>`.
+The most commonly used rotational cipher is `ROT13`.
+
+A `ROT13` on the Latin alphabet would be as follows:
+
+```text
+Plain:  abcdefghijklmnopqrstuvwxyz
+Cipher: nopqrstuvwxyzabcdefghijklm
+```
+
+It is stronger than the Atbash cipher because it has 27 possible keys, and 25 usable keys.
+
+Ciphertext is written out in the same formatting as the input including spaces and punctuation.
+
+## Examples
+
+- ROT5  `omg` gives `trl`
+- ROT0  `c` gives `c`
+- ROT26 `Cool` gives `Cool`
+- ROT13 `The quick brown fox jumps over the lazy dog.` gives `Gur dhvpx oebja sbk whzcf bire gur ynml qbt.`
+- ROT13 `Gur dhvpx oebja sbk whzcf bire gur ynml qbt.` gives `The quick brown fox jumps over the lazy dog.`
+
+
+## Exception messages
+
+Sometimes it is necessary to raise an exception. When you do this, you should include a meaningful error message to
+indicate what the source of the error is. This makes your code more readable and helps significantly with debugging. Not
+every exercise will require you to raise an exception, but for those that do, the tests will only pass if you include
+a message.
+
+To raise a message with an exception, just write it as an argument to the exception type. For example, instead of
+`raise Exception`, you should write:
+
+```python
+raise Exception("Meaningful message indicating the source of the error")
+```
+
+## Running the tests
+
+To run the tests, run `pytest rotational_cipher_test.py`
+
+Alternatively, you can tell Python to run the pytest module:
+`python -m pytest rotational_cipher_test.py`
+
+### Common `pytest` options
+
+- `-v` : enable verbose output
+- `-x` : stop running tests on first failure
+- `--ff` : run failures from previous test before running other test cases
+
+For other options, see `python -m pytest -h`
+
+## Submitting Exercises
+
+Note that, when trying to submit an exercise, make sure the solution is in the `$EXERCISM_WORKSPACE/python/rotational-cipher` directory.
+
+You can find your Exercism workspace by running `exercism debug` and looking for the line that starts with `Workspace`.
+
+For more detailed information about running tests, code style and linting,
+please see [Running the Tests](http://exercism.io/tracks/python/tests).
+
+## Source
+
+Wikipedia [https://en.wikipedia.org/wiki/Caesar_cipher](https://en.wikipedia.org/wiki/Caesar_cipher)
+
+## Submitting Incomplete Solutions
+
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

rotational-cipher/rotational_cipher.py

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+def rotate(text, key):
+    pass

rotational-cipher/rotational_cipher_test.py

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+import unittest
+
+from rotational_cipher import rotate
+
+# Tests adapted from `problem-specifications//canonical-data.json` @ v1.2.0
+
+
+class RotationalCipherTest(unittest.TestCase):
+    def test_rotate_a_by_0_same_output_as_input(self):
+        self.assertEqual(rotate("a", 0), "a")
+
+    def test_rotate_a_by_1(self):
+        self.assertEqual(rotate("a", 1), "b")
+
+    def test_rotate_a_by_26_same_output_as_input(self):
+        self.assertEqual(rotate("a", 26), "a")
+
+    def test_rotate_m_by_13(self):
+        self.assertEqual(rotate("m", 13), "z")
+
+    def test_rotate_n_by_13_with_wrap_around_alphabet(self):
+        self.assertEqual(rotate("n", 13), "a")
+
+    def test_rotate_capital_letters(self):
+        self.assertEqual(rotate("OMG", 5), "TRL")
+
+    def test_rotate_spaces(self):
+        self.assertEqual(rotate("O M G", 5), "T R L")
+
+    def test_rotate_numbers(self):
+        self.assertEqual(rotate("Testing 1 2 3 testing", 4), "Xiwxmrk 1 2 3 xiwxmrk")
+
+    def test_rotate_punctuation(self):
+        self.assertEqual(rotate("Let's eat, Grandma!", 21), "Gzo'n zvo, Bmviyhv!")
+
+    def test_rotate_all_letters(self):
+        self.assertEqual(
+            rotate("The quick brown fox jumps over the lazy dog.", 13),
+            "Gur dhvpx oebja sbk whzcf bire gur ynml qbt.",
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()