Rails%203%20In%20Action

Behavior-driven development
Now when you run this feature, it’ll tell you there’s an undefined method balance,
but didn’t you just define that?
When I take out 10
undefined method `balance' for # (NoMethodError)
Actually, the method you defined was balance= (with an equals sign), which is a setter
method. balance (without an equals sign) in this example is a getter method, which is
used for retrieving the variable you set in the setter method. Not all methods without
equal signs are getter methods, however. To define this method, switch back into lib/
account.rb and add this new method directly under the setter method, as shown in the
following listing.
Listing 2.30 accounts/lib/account.rb
def balance=(amount)
@balance = amount
end
def balance
@balance
end
Here you define the balance= and balance methods you need. The first method is a
setter method, which is used to set the @balance instance variable on an Account object
to a specified value. The balance method returns that specific balance. When you run
this feature again, you’ll see a new error:
When I take out 10
String can't be coerced into Fixnum (TypeError)
./features/step_definitions/account_steps.rb:10:in `-'
This error occurred because you’re not storing the balance as a Fixnum but as a
String. As mentioned earlier, the variable returned from the capture group for the
second step definition is a String. To fix this, you coerce the object into a Fixnum by
calling to_i 8 inside the setter method, as shown in the following listing.
Listing 2.31 accounts/lib/account.rb
def balance=(amount)
@balance = amount.to_i
end
Now anything passed to the balance= method will be coerced into an integer. You also
want to ensure that the other value is also a Fixnum. To do this, open features/
step_definitions/account_steps.rb and change the third step to look exactly like the following
listing.
8 For the sake of simplicity, we use to_i. Some will argue that to_f (converting to a floating-point number) is
better to use for money. They’d be right. This is not a real-world system, only a contrived example. Chill.
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