Introduction and Setting Up¶
What is tdd, imagine a situation where are cooking it entails using different spices salts, onions and sugar am not sure what is end goal, am not a good cook after all but you get the point we are cooking, put the salt taste, or should i say testing if it is enough, the same applies to amount sugar and so on your target making meal which default free if may use the phrase.So thats what tdd is all about testing as you developing.
There several libraries or gems which helps in test driven development in ruby, but use rspec feel free to explore others.So what exactly is a gem or library you may ask lets take the cooking anology, you how
Introduction to Rspec¶
First install rspec using command
gem install rspec.
For more check rspec docs
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$mkdir bank $cd bank $ rspec --init $ create .rspec $ create spec/spec_helper.rb
We create a directory
bank where our project will live, the we initialize rspec using
rspec --init creating
spec_helper.rb, .rspec is well we put our setting
will create our spec file inside spec folder this not necessary but it is a the common convention.
$ cd spec $ touch account_spec.rb
Note _spec format of our i.e account_spec.rb. This is where is our test our lives. Add the following code on file account_spec.rb
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require './lib/account.rb' describe Account do it "verify amount deposit to accurate" do account1 = Account.new deposit = account.deposit(1000) expect(deposit).to eq 1000 end end
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$ rspec $ An error occurred while loading ./spec/account_spec.rb. Failure/Error: require '.lib/account.rb' LoadError: cannot load such file -- .lib/account.rb # ./spec/account_spec.rb:1:in `<top (required)>' No examples found. Finished in 0.00018 seconds (files took 0.09744 seconds to load) 0 examples, 0 failures, 1 error occurred outside of examples
There is an error yep we yet to create the file
account.rb lets do just that .
Lets create a directory
lib in the root directory(bank) and creat account.rb file and rerun the test
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$mkdir lib && touch lib/account.rb $rspec An error occurred while loading ./spec/account_spec.rb. Failure/Error: describe Account do it "verify amount deposit to accurate" do account1 = Account.new deposit = account.deposit(1000) expect(deposit).to eq 1000 end end NameError: uninitialized constant Account # ./spec/account_spec.rb:3:in `<top (required)>' No examples found. Finished in 0.0002 seconds (files took 0.10203 seconds to load) 0 examples, 0 failures, 1 error occurred outside of examples
Take note on the where the error is
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NameError: uninitialized constant Account # ./spec/account_spec.rb:3:in `<top (required)>' No examples found.
This give a hint that we need to create either a class Account or module but since it involve instance it will be class.We give test what it wants according to failure. So let to that remember our aim is to make the test pass and refactor later.
class Account end
run the test again using rspec command and the error we be like so(check verbose form on your terminal)
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Failure/Error: deposit = account1.deposit(1000) NoMethodError: undefined method `deposit' for #<Account:0x000055eae7874510>
It is important to note is
1 example, 1 failure our tests are called example, try finding out why.
So lets deal with our failure by creating method deposit like so: account.rb 2
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class Account def deposit end end
You know the drill run
try figuring out the error uh!! our deposit is expecting a parameter and we gave none.lets fix that..
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class Account def deposit(amount) end end
this is tdd friend we make changes the run the test do that hopefully you know how and am proud of you for that.
there is a failure we are expecting
1000 we got
nil.I wonder how that come to be..Oop method returns what you tell to return, so
deposit return obediently return
nil honestly that what you told it to do return.How do fix that,it
is the easiest thing you done so far give it return value of
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class Account def deposit(amount) 1000 end end
We made a change our rule remains the same, you guess it right the test.
Boom!!! Jackpot trust that is happiest of programmer's life tests are passing everything is
Now come the refactor i.e perfect our code what if the deposit was 2000.what happens ok try giving our method
*account.rb 5 *
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class Account def deposit(amount) 2000 end end
Run the test and the happen moment is gone our testing expect
1000 but what is getting is
2000.So what the best foward,
when amount deposit will actually our deposit therefore deposit method should return amount like so:
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class Account def deposit(amount) amount end end
Run the test
Take notes of these activities we did: - We first wrote the test and never changed but rather changed our code to make test pass - Upon passing we refactored our code with confindence - Then made it pass again
use tdd to solve this¶
- Modify our code to use attr_accessors instead of explictly defining deposit method
- Account to have a name and the name must not be longer 8 characters, remove blanks (blank in this case include a
tab or spacebar input),if it surpasses 8 character it should warn us with message
account name should at most 8 characterif it is empty it display an error message should
account name can't be blank.