Sunday, January 15, 2012

Regular Expressions: A Tester’s Best Friend

Okay, I feel I am entitled to a bit of hyperbole, but I think regular expressions are great.  I like them for two reasons.  One is they are a programming language, and many programmers do not know regular expressions very well.  It is always great when the testing team has a technical advantage over the application developers.

The first reason is a bit lame.  The real reason I like regular expressions is that they enable you to have some much power in your automated tests while keeping the test framework very simple.

For those unfamiliar with regular expressions, regular expressions enable you to match patterns in strings of text using a simple syntax of reserved characters and patterns.  Regular expressions range from something simple like “Bob.*Jones” where “.*” is essentially a wildcard where matches include “Bob the wildman Jones” and “Bob Jones”  You can also make regular expressions to make sure that a value matches a date format or social security format or use a regular expression match an application validation message where the message changes in some predictable way when a test runs.

In our test framework, we use regular expressions for all automation components involved with verification.  For example, we use many “verify data” components.  In these components, you enter the expected value for a field in the application under test.  All our fields are regEx enabled, and typically this means that you enter an exact string value or a regular expression pattern to match in the test.  This means you have a very simple test with a lot of power.

Implementation note:  There was a point of the development of our automation framework, we had to make decisions about whether to use regular expressions and how to use them.  As much as it pains me to say, the biggest factor was whether the use of regular expressions would be too hard for testers.  Fortunately, we decided that testers are smart enough to handle regular expressions (and of course, they are!)

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