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Unit Testing: What? Why? How?
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John Blackbourn
February 14, 2017
Technology
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Unit Testing: What? Why? How?
Slides from my talk at WP Hooked, February 2017.
https://www.meetup.com/wp_hooked/
John Blackbourn
February 14, 2017
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Transcript
Unit Testing: What? Why? How?
John Blackbourn WordPress core developer Working with WordPress for 10+
years Senior Engineer at Human Made @johnbillion
Unit Testing: What? Why? How?
You’re Going to L VE Unit Testing
That’s Enough of That
Unit Testing: What? Why? How?
A unit test is a piece of code which exists
only to verify expectations about the behaviour of another piece of code Verification
a.k.a. “Does my function do what I expect it to
do?”
A unit test operates in isolation in order to avoid
external interference Isolated
Tests typically run on the command line CLI
Tests are highly efficient because they're quickly repeatable Automated
Crossing your fingers and hoping… is not a unit test
Unit Testing: What? Why? How?
A unit test can cover many scenarios and never misses
anything Accuracy
Unit tests give you increased assurance that changes are less
likely to cause breakage Assurance
Unit tests give you confidence to make changes Confidence
Unit tests help you write better code Smaller functions Separation
of concerns Quality
Unit tests can be liberating Clarity
Unit Testing: What? Why? How?
None
None
None
None
“But I know that false isn’t true”
None
Arrange Act Assert AAA
Each time a WordPress test runs, it operates on a
fresh installation Remember
None
None
None
None
Accuracy Assurance Confidence Quality?… The Result
Assertions assertTrue( $actual ) assertFalse( $actual ) assertEquals( $expected, $actual
) assertCount( $expected, $actual ) assertObjectHasAttribute( $key, $actual ) assertArrayHasKey( $key, $actual ) assertWPError( $actual ) assertCanonical( $actual, $expected )
a.k.a. A Real World Gotcha Type Juggling Kills Me
None
None
WUT
None
Provide Verification Isolated Automated Recap
Accuracy Assurance Confidence Quality Recap
Arrange Act Assert Recap
I Hope You’ll Fall In L VE With Testing
Read the WordPress Unit Tests Visit PHPUnit website for reference
Check out WP-CLI scaffolding What Next?
John Blackbourn @johnbillion