When developing and testing software, Continuous Deployment is important.

The development process is:

• Check out code
• Do the development (writing tests first)
• Run your tests (keeping failing tests to 0)
• Check in code (at least a couple of times a day)
• When code is checked in,  tests should automatically run and deploy the application to a test environment
• When a PBI is completed, a done email can be sent to the Product Owner and/or tester including a link to the test / UAT environments for fast feedback.

Modules/Classes should have enough comments to explain the logic for a second developer to understand.

If you aren't confident releasing to a client, get the Scrum Master to check your first few releases before going to the client.

What is Unit and Integration Testing?

Erich Gamma and Kent Beck created a framework for writing tests during your design phase. These are widely accepted as best practice (in fact, some may consider it extreme).

Some background on these people. Erich is a major contributor of the book Design Patterns (a must read!). Kent is the author of "Smalltalk Best Practices" and Exterme Programming Explained. These are some of the very smart people who pulled together years of experience and patterns that can be used in the design and development of good software.

Their work is JUnit but that is a framework for Java.

JUnit was ported to .NET and is called NUnit

There is a great article you should read called Test Infected.

Read more: Rules to Better Unit Tests