Unit Testing by Example

Everyone tells you that you need to write tests. You tried it, but your tests ended up not very useful and consumed valuable time. What to test? What conditions to write? Through realistic examples, this presentation will take you from var_dump() and ease you into the testing business. All this without losing sight of the tight deadlines. You will come out of this presentation with a renewed interest in writing unit tests.

Transcript

1. FooLab http://foolab.ca @foolabca Unit Testing by Example ConFoo - February 26, 2014
2. FooLab Objectives • Make testing enjoyable. • Make it useful. • Reduce pre-release stress. 2
3. FooLab Anna Filina 3 • I help projects ship on time. • I train and mentor developers. • I code and optimize.
4. FooLab You don’t need 100% coverage
5. FooLab You don’t become an expert overnight
6. 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); } 6
7. FooLab Step 2: improve code $item = new CartItem("Skyrim", 30); $item->setQuantity(2); $cart->addItem($item); $this->assertEquals(0, $cart->getShipping()); $this->assertEquals(60, $cart->getTotal()); 7
8. FooLab Step 2: improve code public function getShipping() { if ($this->getSubtotal() >= 40) { return 0; } else { return 15; } } 8
9. 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()); 9
10. FooLab Step 3: write code public function getTotal() { ... $taxes = $this->getApplicableTaxes(); foreach ($taxes as $tax) { $total += $subtotal * $tax->getPercent(); } ... } 10
11. 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 11
12. 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()); 12
13. FooLab Advantages • More tests. • Easy to write. • Never fall too far. 13
14. 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]); 14
15. FooLab Tips • How it’s not supposed to work. • Plan for exceptions. • Focus on realistic scenarios. 15
16. 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 16