How to name our Unit Tests

Connection - 10'

Imagine we want to test this method :

public static boolean isLeapYear(int year)

• Here are the associated requirements

How would you name your first test ?

• Ask attendees to note on a Sticky Note what is the name of their first test

• Compare the different styles

• What do they prefer (Dot voting)

Concepts - 10'

Tests names v1

yearsNotDivisibleBy4...
yearsDivisibleBy4ButNotBy100...
yearsDivisibleBy100ButNotBy400...
yearsNotDivisibleBy400...

• Is it readable ?

• What is the intent ?

Tests names v2

years_not_divisible_by_4...
years_divisible_by_4_but_not_by_100...
years_divisible_by_100_but_not_by_400...
years_not_divisible_by_400...

• Is it more readable ?

• What is the intent ?

Tests names v3

years_not_divisible_by_4_are_not_leap_years
years_divisible_by_4_but_not_by_100_are_leap_years
years_divisible_by_100_but_not_by_400_are_not_leap_years
years_not_divisible_by_400_are_not_leap_years

• Intent is more clear, isn’t it ?

Tests names v4

public class Leap_year_spec {
    public static class A_year_is_a_leap_year {
        @Test public void if_it_is_divisible_by_4_but_not_by_100()...
        @Test public void if_it_is_divisible_by_400()...
    }
    
    public static class A_year_is_not_a_leap_year {
        @Test public void if_it_is_not_divisible_by_4()...
        @Test public void if_it_is_divisible_by_100_but_not_by_400()...
    }
}

• Express what the class should be able to do

• Read it as a full sentence : express a true business specification

• You should avoid technical terms

Concrete Practice - 30'

• Choose a Kata on Coding Dojo

• Extract the Test Cases you want to write

  • Define the structure and naming of your tests

Conclusion - 10'

Imagine you use this naming technique during the next 6 months :

• What has changed ?

• Who else have noticed those changes ?

• What are the impacts on your day to day ?

Resources

• https://www.youtube.com/watch?v=azoucC_fwzw&ab_channel=BuildStuff