Unit Testing By Example

Unit Testing By Example

Everyone says you need to test. You know the theory, but you do not know where to begin. What should you test? What cases should you write? Using realistic, pragmatic examples, this presentation will take you away from var_dump and ease you into the testing business until you are ready to do TDD without losing sight of tight deadlines.

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Anna Filina

May 25, 2016
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  1. foolab.ca | @foolabca Unit Testing by Example php[tek], St. Louis

    - May 25, 2016
  2. Objectives • Make testing enjoyable. • Make it useful. •

    Reduce pre-release stress. 2
  3. Anna Filina • Developer • Problem solver • Teacher •

    Advisor • FooLab + ConFoo 3
  4. You Don’t Become an Expert Overnight

  5. You Don’t Start With 100% Coverage

  6. Testing Without Automation

  7. Step 1: Found Bug $item = new CartItem("Overwatch", 30); $item->setQuantity(0.1);

    $this->assertEquals(1, $item->getQuantity()); 7
  8. Step 1: Found Bug $item = new CartItem("Overwatch", 30); $item->setQuantity(0.1);

    $this->assertEquals(1, $item->getQuantity()); public function setQuantity($qty) { $this->qty = ceil($qty); } 8
  9. Regression Testing

  10. Step 2: Improve Code $item = new CartItem("Overwatch", 30); $item->setQuantity(2);

    $cart->addItem($item); $this->assertEquals(0, $cart->getShipping()); 10
  11. Step 2: Improve Code public function getShipping() { if ($this->subtotal

    >= 40) { return 0; } else { return 15; } } 11
  12. Test Both Cases $item = new CartItem("Overwatch", 30); $item->setQuantity(1); $cart->addItem($item);

    $this->assertEquals(15, $cart->getShipping()); 12
  13. Step 3: New Code public function getTotal() { //... $taxes

    = $this->getApplicableTaxes(); foreach ($taxes as $tax) { $total += $subtotal * $tax->getPercent(); } //... } 13
  14. Step 3: New Code array (size=2) 0 => array (size=2)

    'name' => string 'GST' (length=3) 'percent' => float 0.05 1 => array (size=2) 'name' => string 'QST' (length=3) 'percent' => float 0.09975 14
  15. Step 3: New Code $cart = new Cart(); $taxes =

    $cart->getApplicableTaxes(); $this->assertInternalType('array', $taxes); $this->assertCount(2, $taxes); $gst = $taxes[0]; $this->assertEquals(0.05, $gst['percent']); 15
  16. Advantages • More tests. • Easy to write. • Never

    fall too far. 16
  17. Data From CSV

  18. Step 4: Before (TDD) $import = new CatalogImport(); $products =

    $import->parseFromCsv('catalog.csv'); $this->assertInternalType('array', $products); $this->assertCount(2, $products); $this->assertArrayHasKey('name', $products[0]); $this->assertArrayHasKey('price', $products[0]); 18
  19. Tips • How it’s not supposed to work. • Plan

    for exceptions. • Focus on realistic scenarios. 19
  20. Don't Waste Time $total = 5; $this->assertNotNull($total); 20

  21. How Many Cases? 21

  22. Cyclomatic Complexity 22

  23. Execution Paths public function getShipping() { if ($this->subtotal >= 40)

    { return 0; } return $this->shipping; } 23
  24. Example 24 start product loop free shipping? gift wrap? end

  25. Zero Times foreach ($products as $product) { $total = $product->price

    * $product->quantity; } if ($total > 0) { echo 'found'; } 25
  26. Multiple Times $total = 0; foreach ($products as $product) {

    $total = $product->price * $product->quantity; } if ($total > 0) { echo 'found'; } 26
  27. 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. 27
  28. Anna Filina • Development. • Fix bugs & performance issues.

    • Workshops on testing, frameworks & APIs. • Advisor on testing strategy, legacy code. 28
  29. @afilina afilina.com joind.in