tea-time/presentation/04_expect.slides

!SLIDE
# `expect`

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# What should we get as an output?

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``` coffeescript
describe 'Cat', ->
  describe '#meow', ->
    it 'should meow correctly', ->
      expect(cat.meow()).toEqual('meow')
```

!SLIDE
# Wait, we need a cat.

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``` coffeescript
describe 'Cat', ->
  describe '#meow', ->
    it 'should meow correctly', ->
      cat = new Cat()

      expect(cat.meow()).toEqual('meow')
```

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``` coffeescript
# code-under-test

class this.Cat
  meow: ->
```

!SLIDE larger
``` javascript
// safety wrapper to prevent global pollution
(function() {
  // ...but we want to pollute the Cat class
  this.Cat = (function() {
    function Cat() {}
    Cat.prototype.meow = function() {};
    return Cat;
  })();
})(this) // this is window in a browser
```

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# Run it!

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```
1 spec, 1 failure

Expected undefined to equal 'meow'.
```

!SLIDE
# Make it meow!

!SLIDE even-larger
``` coffeescript
class this.Cat
  meow: -> "meow"
```

!SLIDE even-larger
```
1 spec, 0 failures
```

!SLIDE
# Here's what you should have meow...

!SLIDE even-larger
``` coffeescript
# spec

describe 'Cat', ->
  describe '#meow', ->
    it 'should meow correctly', ->
      expect(cat.meow()).toEqual('meow')
```

!SLIDE even-larger
``` coffeescript
# code-under-test

class this.Cat
  meow: -> "meow"
```