Intoduction to Unit Testing

Using JUnit to structure Unit Testing

SE-2030Dr. Rob Hasker

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Based on material by Dr. Mark L. Hornick

How can you test your code?

SE-2030Dr. Rob Hasker

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How can you test your app?

Run the app with inputs that should produce a known output, and verify the actual output

One problem with this approach may be that you can’t make your app accept “bad” inputs; thus you may not be able to force all possible if-then-else blocks of the app’s classes’ methods to execute

Write a separate “test” program that is designed to exercise the classes and methods of the “production” app

A problem with this might be gathering the results of the exercises and determining whether each one passed or failed.

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What is Unit Testing?

Creating special-purpose test code that exercises specific classes of your application is called Unit Testing

Such test code usually exercises one method at a time (or a small set) whenever possible.

The tests usually include exercising the methods in “boundary conditions” by force-feeding the methods “bad” arguments, such as nulls.

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What is JUnit?

JUnit is an open source Java testing framework used to write and run repeatable tests.

It is built in to Eclipse. JUnit provides a framework for executing tests

General form of tests: create data, check results Operations to check results: assertEquals, assertTrue,

assertFalse, etc. Minimal work needed by developer to set up, run

tests

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Demonstration

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Assertions in Junit

See http://junit.sourceforge.net/javadoc/ assertEquals assertTrue assertFalse assertNotSame assertNull assertArrayEquals fail

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