Git Repository Metrics

Overview

Git repositories are more than just a way to keep track of your source code, they provide a history of software development activities that can be studied. In software engineering research, mining Git repositories is a common method for understanding how a software development team collaborates on a project.

In this activity, we will do some basic mining of Git repositories. We will take the standard output from Git's log command, which can be accessed by this command:

git log

Note: If you run this by itself on the command line on hamilton within your repository, you can scroll with your up and down keys, or with page-up and page-down. Press "q" to quit. If you run this command as a part of standard output redirection, you don't need to worry about scrolling.

Activity

Download git_metrics.rb and the accompanying unit test test_git_metrics.rb.

We also provide two test data sets, taken from the Ruby Progress Bar gem. Download the two test files: ruby-progressbar-short.txt and the longer one ruby-progressbar-full. Examine these logs to see what the format looks like so you can parse it properly.

Using our unit testing technique and using the test data given, write the three given methods:

• Number of commits: the total number of commits logged in the file. Examine the test logs to determine the pattern.
• Number of developers: the total number of unique developers who committed in the logs. Examine the test logs to determine the pattern. You may assume that emails make a developer unique, that is, if a developer has two different emails they are counted as two different people.
• Number of days in development: computed by the newest date in the log file minus the oldest date in the log file plus one (because if you started and stopped working on a file today, you worked on it for one day). If there are no dates recorded, then the number of days is 0.
  You cannot assume any order of commits (e.g. you cannot assume that the newest commit is first). To accomplish this, use the DateTime class (obtained by using require 'date'). The DateTime class provides comparison, subtraction, and the method DateTime.parse can handle by default the date formatting that Git handles.

For your unit tests, we have you given some tests to demonstrate what some methods should expect and return. Write at least five more unit tests (minimally two per method) for git_metrics.rb

To run the full program from the command line with test data, it looks like this:

  $ ruby git_metrics.rb < ruby-progressbar-short.txt
  Number of commits: 3
  Number of developers: 2
  Number of days in development 4

For the longer data set the output looks like this:

  $ ruby git_metrics.rb < ruby-progressbar-full.txt
  Number of commits: 430
  Number of developers: 33
  Number of days in development 1806

Analyze Your Own Repo

For fun, if you want to test this out on your own repository, use this command

git log | ruby git_metrics.rb

Submission

As usual, fill out an Activity Journal. Submit via Git to the GitMetrics folder