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TDD 101
1. Test Driven Development
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Test Driven Development
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Test Driven
Development
It’s a discipline
Unit test first
Only code to pass the test
Loop of minimal changes
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Classic post-test vs TDD
Test
Code
Design
Design
Code
Test
Waterfall
TDD
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TDD laws
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TDD laws
You can't write any
production code
until you have first
written a failing unit
test.
You can't write
more of a unit test
than is sufficient to
fail, and not
compiling is failing.
You can't write
more production
code than is
sufficient to pass
the currently failing
unit test.
Robert C. Martin
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TDD cycle
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TDD cycle
Write a
failing test
Write just
enough code
to make the
test pass
Refactor if
needed
(mostly
reduce
duplication)
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Write a failing test
Write a test to
prove a simple case
Run the test and
see how it fails
Errors == test fails
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Make the test pass
Write production
code until:
• all errors are fixed
• the test passes
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Refactor
Keep tests passing
Remove duplication
Improve design
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Outcomes
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Outcomes Always backed by tests
Decoupled design
Automatically you get:
• full coverage
• regression tests
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Code
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Write a failing test
class ValidateNifTest extends TestCase
{
public function testRealNIFShouldBeValid()
{
$validateNif = new ValidateNif();
$this->assertTrue($validateNif->isValid('00000000T'));
}
}
Error : Class 'Dojo\ValidateNif\ValidateNif' not found
/Users/franiglesias/PhpstormProjects/dojo/tests/Dojo/ValidateNif/ValidateNifTest.php:
13
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Make the test pass
class ValidateNif
{
}
Error : Call to undefined method Dojo\ValidateNif\ValidateNif::isValid()
/Users/franiglesias/PhpstormProjects/dojo/tests/Dojo/ValidateNif/ValidateNifTest.php:
14
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Make the test pass
Failed asserting that null is true.
/Users/franiglesias/PhpstormProjects/dojo/tests/Dojo/ValidateNif/ValidateNifTest.php:
14
class ValidateNif
{
public function isValid(string $nif)
{
}
}
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Make the test pass
OK (1 test, 1 assertion)
class ValidateNif
{
public function isValid(string $nif):bool
{
return true;
}
}
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Hands on…
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Fizz Buzz Kata
stage 1
Write a program that prints the numbers
from 1 to 100.
But for multiples of three print “Fizz”
instead of the number and for the
multiples of five print “Buzz”.
For numbers which are multiples of both
three and five print “FizzBuzz “.
http://codingdojo.org/kata/FizzBuzz/
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Fizz Buzz Kata
stage 2
A number is “Fizz" if it is divisible by 3 or
if it has a 3 in it
A number is “Buzz” if it is divisible by 5 or
if it has a 5 in it
http://codingdojo.org/kata/FizzBuzz/
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Fizz Buzz Kata
stage 3
We want all these rules configurable.
http://codingdojo.org/kata/FizzBuzz/