Considering my exaggerated title, I will try to explain it briefly.

The test driven is a huge advancement from Kent Beck that enhances developer confidence and code quality and slows the developer's hair whitening. Although it has been popular for 10 years, I still see people saying that this technology is difficult. I don't think so. The technology itself is very simple. Below I use a simple example to illustrate.

Create directory

I use a simple calculator to illustrate, create an empty directory calc-tdd

mkdir calc-tdd
cd calc-tdd
touch test_calc.rb
touch calculator.rb

Now that we have the directory and two files, let's start writing the code test_calc.rb and write the test first.

Write Test

#test_calc.rb

require "minitest/autorun"

require "./calculator.rb"

class TestCalculator < MiniTest::Test
    def test_add
        calc = Calculator.new
        assert calc.add(1, 2) == 3
    end
end

After the test is finished, you can run it.

ruby test_calc.rb

The result will be reported because the code has not been implemented.

Implementation code

#calculator.rb

class Calculator
    def add(a, b)
        a + b
    end
end

Ok, run the test again and you will find the code passed. It’s simple enough, look at the watch for five minutes.

Next you can add a subtraction test sub yourself.

Follow-up can learn the usage of setup and teardown, and of course there are many things worth learning, such as RSpec.

in conclusion

TDD is a huge improvement, and the basic concept is simple. Of course, the test itself is a complex field, and there is still a lot to learn to become a test expert.