Correcting lots of stuff

What was Wrong

While writing unittests I went off-track. Thankfully, mithro guided me at correct time. Two major wrong things I was doing were:

1. For testing purposes, to each and every function in my code I was adding input validation statements, so that I did not get any TypeError or ValueError while running it. Instead of doing this, I should have made exception handlers. So my last few commits were not useful at all and I had to remove them.
2. I was using setters and getters in my code. I had added them to give extra abstraction to the user. However, I learnt that in python these are seldom used. So, I had to remove these lines from the code.

These things were the reason I delayed writing this blog post.

Commits:

A rather long list of commits:

• exceptions for run, terminate and kill: af1bd7c8645b82fd2a725655fd6905709d6d8d45
• exceptions for run, terminate and kill: 51dada1c0b16e8e3fd90eb7a967fb583b87d76f8
• Exception handling for Server.run and py.tests: 8807d07c2d98d5d39b8a0c22eabfc77b619369e1
• exception handling for server process creation: 832e0cb1948c601faa20292b6883a4d4d12bb1dc
• added exception for subprocess: 8ef1346d40822b47e3cba16fd42848843a265783
• gst-option added and updated connection.py: 9f8434cb9f06a25d6f9e3fec22a04289d2ba458e
• Removed wrong unittests: 269d307d5edd1b6d621457038b9148152bf14e12
• Made helpers.py and testsource.py pythonic: 18608b8702826279711ed9d749f435b4340607ee
• Made server.py pythonic: abecf31fb2d429a84288026008e44feae3e8640c
• Made connection.py pythonic and removed dbus.py: 2c7c7c03b527885c6bc0043dd73a0aeb7d29444d
• Made connection.py pythonic and removed dbus.py: 82cd61beadbd499f9424409c218bcae5b4840217
• fixed typo: e11aaea2b080d63f55a95b682593d4e6c50c1606
• Fixed problems: 48e1742478627741b7c6def34ab2c2f972609b82

Exception Handling

From above experience I learnt that I had to put exception handlers in my code. I had very little knowledge of exception handlers and absolutely no experience.

Some good links that I found were very useful in the field of exception handling and testing:

• http://pythontesting.net/framework/pytest/pytest-introduction : This page nicely explains how to use py.test.
• http://www.itmaybeahack.com/book/python-2.6/html/p02/p02c07_exceptions.html: A very long and very good page which explains exception handling to its core.
• http://stackoverflow.com/questions/6180185/custom-python-exceptions-with-error-codes-and-error-messages: Nicely explains how to create custom exception classes
• http://blog.ianbicking.org/2007/09/12/re-raising-exceptions/: Nicely explains how to raise and re-raise exceptions in python

After spending lots of time on reading exception handling in python, I made a few changes to the code, where I defined some custom Exceptions like PathError: Raised when a wrong path is specified to the run the gst-switch-srv process. Another one is ServerProcessError: Raised when something wrong happens with the process running like a OSError indicating some internal fault.

Things to do..

Add exception handling for all modules and write py.test testing modules for testing them