The wrong ways to do it
With RSpec, there are three general ways to avoid duplication - initializing the same variables over and over again - in writing test units. The last way is better than the others.
1. Using before with instance variables.
RSpec.describe Cat do
before do
@cat = Cat.new('Garfield', 'orange')
end
it 'has a name' do
expect(@cat.name).to eq('Garfield')
end
it 'has a color' do
expect(@cat.color).to eq('orange')
end
end
The before block reinitializes the @cat instance variable before each example, but it’s not efficient to initialize it over and over again. Furthermore, if the programmer uses the wrong instance variable name in the test, variable will be returned as nil, instead of throwing a more specific error message.
2. Helper methods
RSpec.describe Cat do
def cat
Cat.new('Garfield', 'orange')
end
it 'has a name' do
expect(cat.name).to eq('Garfield')
end
it 'has a color' do
expect(cat.color).to eq('orange')
end
end
The above code defines a local method #cat that creates a new instance of cat and returns it whenever it’s called. The problem with using a helper method to reduce duplication is that you will get errors when trying to change the object’s properties by calling the method with setters.
My next post will go into more detail on the third and final method.