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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Transcript

  1. 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
  2. 10.

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

    $cart->addItem($item); $this->assertEquals(0, $cart->getShipping()); 10
  3. 11.

    Step 2: Improve Code public function getShipping() { if ($this->subtotal

    >= 40) { return 0; } else { return 15; } } 11
  4. 13.

    Step 3: New Code public function getTotal() { //... $taxes

    = $this->getApplicableTaxes(); foreach ($taxes as $tax) { $total += $subtotal * $tax->getPercent(); } //... } 13
  5. 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
  6. 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
  7. 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
  8. 19.

    Tips • How it’s not supposed to work. • Plan

    for exceptions. • Focus on realistic scenarios. 19
  9. 25.

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

    * $product->quantity; } if ($total > 0) { echo 'found'; } 25
  10. 26.

    Multiple Times $total = 0; foreach ($products as $product) {

    $total = $product->price * $product->quantity; } if ($total > 0) { echo 'found'; } 26
  11. 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
  12. 28.

    Anna Filina • Development. • Fix bugs & performance issues.

    • Workshops on testing, frameworks & APIs. • Advisor on testing strategy, legacy code. 28