kjwilliamson / copy-special

Copyspecial

You will complete functions inside of copyspecial.py. This program takes one or more directories as its arguments. A "special" file is defined as one where the name contains the pattern __w__ somewhere, where the w is one or more word characters. The provided main() function includes code to parse the command line arguments, but the rest is up to you! Write functions to implement the features below and modify main() to call your functions.

Here are some suggested functions to create in your solution (details below):

• get_special_paths(dir) — returns a list of the absolute paths of the special files in the given directory, but not deeper (no recursive search)
• copy_to(paths, dir) — given a list of file paths, copies those files into the given directory
• zip_to(paths, zippath) — given a list of file paths, zip those files up into the given zip path

Part A - manipulating file paths

Gather a list of the absolute paths of the special files in all the directories. In the simplest case, just print that list (here, the . after the command is a single argument indicating the current directory). Print one absolute path per line.

$ python copyspecial.py .
/Users/daniel/Documents/github/kenzie/backend-copy-special-assessment/xyz__hello__.txt
/Users/daniel/Documents/github/kenzie/backend-copy-special-assessment/zz__something__.jpg

We'll assume that names are not repeated across the directories (optional: check that assumption and error out if it's violated).

Part B - file copying

If the --todir dir option is present on the command line, do not print anything. Instead, copy the files to the given directory, creating the directory if necessary. Use the shutil standard library module for file copying.

$ python copyspecial.py --todir tmp/fooby .
$ ls tmp/fooby
xyz__hello__.txt        zz__something__.jpg

Part C - calling an external program

If the --tozip zipfile option is present at the start of the command line, run this command: zip -j zipfile <list all the files> from within your code (the subprocess standard library module can help you with this). This will create a zipfile containing the files. Just for fun/reassurance, also print the command you are about to execute (e.g., zip -j <zipfile> <each of the file paths>). (Note to Windows users: Windows does not come with a program to produce standard .zip archives by default, but you can download the free Zip program here.)

$ python copyspecial.py --tozip tmp.zip .
Command I'm going to do:  
zip -j tmp.zip /Users/daniel/Documents/github/kenzie/backend-copy-special-assessment/xyz__hello__.txt /Users/daniel/Documents/github/kenzie/backend-copy-special-assessment/zz__something__.jpg

If the child process exits with an error code, your program should exit, displaying the error code and printing the command's output. Test this by trying to write a zip file to a directory that does not exist.

$ python copyspecial.py --tozip /no/way.zip .
Command I'm going to do:  
zip -j /no/way.zip /Users/daniel/Documents/github/kenzie/backend-copy-special-assessment/xyz__hello__.txt /Users/daniel/Documents/github/kenzie/backend-copy-special-assessment/zz__something__.jpg

zip I/O error: No such file or directory
zip error: Could not create output file (/no/way.zip)

Notice the last two lines of output above e.g. zip I/O error: No such file ... This error message is generated by the zip utility itself, and is normally printed to the sys.stderr console device which is the same device as the regular sys.stdout used by print(). You should not hard-code this message yourself. You may ask, 'But if I call zip as a child process, how can I flow this error text from the child process to my console device?' The answer is to surround your call to subprocess with a try/except block, and capture the exception that zip will generate as a child process. Read about subprocess exceptions here.

The error text is contained within the exception instance, and you can retrieve it and print it. You will need to read the documentation pages of subprocess.run or subprocess.check_output to understand what kind of exception will be raised in this case, and how you should catch it. YES the documentation is dense, but as a software engineer it is important to learn how to read and make sense of documentation no matter the density or sparsity.

Guidelines

• Use the subprocess library to launch zip directly as a command line utility from within your program
• Don't use the zipfile library.
• Your code style should be able to pass a PEP8 (flake8) test
• Indents should be 4 spaces (not 2)
• Variable names should be well chosen and meaningful and should be in snake_case
• Include docstrings as the first line of a function

Testing with Unittest

This assignment also has separate unit tests to help you during development. The unit tests are located in the tests folder; you should not modify these. Make sure all unit tests are passing before you submit your solution. You can invoke the unit tests from the command line at the root of your project folder:

$ python -m unittest discover tests

You can also run these same tests using the Test Explorer extension built in to the VSCode editor, by enabling automatic test discovery. This is a really useful tool and we highly recommend to learn it.

https://code.visualstudio.com/docs/python/testing#_test-discovery

• Test framework is unittest
• Test folder pattern is tests
• Test name pattern is test*

Submitting your work

To submit your solution for grading, you will need to create a github Pull Request (PR). Refer to the PR Workflow article in your course content for details.