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FooLab
http://foolab.ca
@foolabca
Unit Testing
by Example
ConFoo - February 26, 2014
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FooLab
Objectives
• Make testing enjoyable.
• Make it useful.
• Reduce pre-release stress.
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FooLab
Anna Filina
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• I help projects ship on time.
• I train and mentor developers.
• I code and optimize.
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FooLab
You don’t need
100% coverage
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FooLab
You don’t become an
expert overnight
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FooLab
Step 1: found bug
$item = new CartItem("Skyrim", 30);
$item->setQuantity(0.1);
$this->assertEquals(1, $item->getQuantity());
===
public function setQuantity($qty)
{
$this->qty = ceil($qty);
}
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FooLab
Step 2: improve code
$item = new CartItem("Skyrim", 30);
$item->setQuantity(2);
$cart->addItem($item);
$this->assertEquals(0, $cart->getShipping());
$this->assertEquals(60, $cart->getTotal());
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FooLab
Step 2: improve code
public function getShipping()
{
if ($this->getSubtotal() >= 40) {
return 0;
}
else {
return 15;
}
}
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FooLab
Test both cases
$item = new CartItem("Skyrim", 30);
$item->setQuantity(1);
$cart->addItem($item);
$this->assertEquals(15, $cart->getShipping());
$this->assertEquals(45, $cart->getTotal());
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FooLab
Step 3: write code
public function getTotal()
{
...
$taxes = $this->getApplicableTaxes();
foreach ($taxes as $tax)
{
$total += $subtotal * $tax->getPercent();
}
...
}
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FooLab
Step 3: write code
array (size=2)
0 =>
array (size=2)
'name' => string 'GST' (length=3)
'percent' => float 0.5
1 =>
array (size=2)
'name' => string 'QST' (length=3)
'percent' => float 0.9975
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FooLab
Step 3: write code
$cart = new Cart();
$taxes = $cart->getApplicableTaxes();
$this->assertInternalType('array', $taxes);
$this->assertCount(2, $taxes);
$gst = $taxes[0];
$this->assertEquals(0.5, $gst->getPercent());
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FooLab
Advantages
• More tests.
• Easy to write.
• Never fall too far.
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FooLab
Step 4: before (TDD)
$import = new CatalogImport();
$products = $import->parseFromCsv('test_catalog.csv');
$this->assertInternalType('array', $products);
$this->assertCount(2, $products);
$this->assertArrayHasKey('name', products[0]);
$this->assertArrayHasKey('price', products[0]);
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FooLab
Tips
• How it’s not supposed to
work.
• Plan for exceptions.
• Focus on realistic
scenarios.
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FooLab
Recap
• Testing takes practice
• Write tests when you see
a bug
• Write tests when you
improve code
• Write tests as you write
new code
• Write tests before you
write code
• Test unexpected
scenarios
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