Unit TestingMaintaining Quality

How do you test?

• Testing to date…

Testing Large Systems

• Old school:– Programmers write parts of code• Maybe check tricky bits

– Someone tries to build whole project• Sort out incompatibilities

– Hand it off to testing• This job is awful

Testing Goals

• Principles:– Tests should cover as much code as possible– Tests should be run after any significant change– Tests should not clutter up core source

Testing Goals

• Principles:– Tests should cover as much code as possible– Tests should be run after any significant change– Tests should not clutter up core source

• So:– Tests better be easy to write– Tests better be easy to run– Tests better exist outside normal structure

Unit Tests

• Unit Test : – Tests one module of code– Automated– Run after any changes to code

Other Testing

• Still need:– Integration testing• But easier

– UI testing• But just testing UI code

Doing Unit Testing

• Basic idea:– Write functions TESTS to test your code• Tests can be passed or failed

What does it actually look like?

• Base project– Normal application– Header file(s) for classes– .cpp file(s) for classes– main file with "real" program

What does it actually look like?

• Test project– Special header with test stuff• Included in test files only

– One .cpp file to test each class – New main file to run tests

Building / Running

• Activate / Build / Run standard projectNormal program

Building / Running

• Activate / Build / Run test projectRun unit tests

Details

• catch.hpp

Don't touch

Details

• mainTester.cpp– Has main function• Runs tests automatically

– Can be configured

Details

• CLASSXTESTER.cpp– Includes class.h / catch.hpp– Has TEST_CASEs

Expression that must be true

Machine name - must be unique Description

Details

• CLASSXTESTER.cpp– Includes class.h / catch.hpp– Has TEST_CASEs

Expression that must be true

Machine name - must be unique Description

== doubles

• Not OK to compare doubles with ==

== doubles

• Can write your own function to test for approximate equality:

== doubles

• But Catch includes macro to simplify:– Approx( value )

Details

• Pattern– Make an object– Call functions to be tested– REQUIRE correct data• Must use public methods to access

What Do I Test

• Test public interface• Test every method/construct except…– Trivial one liners:• Usually don't directly test getXXX()

– IO code:• Hard to do from testing frameworks

Features Test Mapping

• Focus on one features per test• Some features may need multiple tests:connect.setURL("http://www.google.com") connect.setURL("www.google.com") connect.setURL("ftp://chemeketa.edu")

isPrime(3) isPrime(4)