Make your Testing Infallible using Emma Code coverage tool

Make your Testing Infallible using Emma Code coverage tool

For good client experience and to ensure quality, our program must be tested thoroughly .We are often not sure, if our test cases execute all of the modified code in the application. Code coverage is a measure used in software testing. It describes the degree to which the source code of a program has been tested. Code coverage is a software engineering technique whereby we can track quality of our test plan/suite by determining simple metrics like the percentage of {classes, methods, lines, etc.} that were executed when the test plan/suite is executed.

Typical Code Coverage Testing Lifecycle

Emma is a java based open source, code coverage tool. Emma reports the percentage of code and the actual lines of code that were executed in an html report. Based on the reports of code coverage, development/QA can add more test cases to increase the coverage. Emma helps to improve the quality of our test cases.

EMMA Code Coverage Life Cycle:

1)      Instrumentation process: Emma adds some code to java classes, [this process is called instrumentation.], when the code in the classes are executed. Output of this process is instrumented application code & metadata file, used later to generate the report. Application specific Meta file is created as a byproduct of instrumentation. The Meta data file is combined with the coverage data file to generate coverage reports. Meta data file is created at compile time.

We can enhance our build scripts (ant/ maven) to include instrumentation process.

2)      Run your test cases.

3)      Code monitoring data is generated in-memory by EMMA as test cases are run on an instrumented application. This data can be dumped onto the file system once testing is complete. EMMA combines the Meta data and coverage data files to generate the reports.

4)      Run the report.

5)      Add new test cases to your Test plan and repeat steps 2 to 4 to get better code coverage.

Reasons of choosing Emma over other Java code coverage tools.

1.                   Emma supports html, xml & text report formats

2.                   Emma injects minimal instrumentation byte code when compared to other tools like Corbetura or Code Cover Emma’s instrumentation process is much faster.

3.                   Doesn’t force a test suite.

4.                   Completely open-source and free tool.

5.                   Is platform independent and works in any Java 2 JVM since 1.2

For more info on Emma visit:  http://emma.sourceforge.net/

What not to do with instrumented code?

Deploy in UAT/ Production: instrumented applications can lead to larger memory usage and performance issues. They should only be used in Dev/QA environments