1 of 13

Testing patterns

Junior Developer Workshop

Kevin Guillaumond

April 7th, 2017

2 of 13

Reference

xUnit Test Patterns

Gerard Meszaros, 2007

http://xunitpatterns.com/

2

3 of 13

Why do we test?

3

Limit number of bugs in production code

Catch defects early

Programming mistakes
Regression

4 of 13

When we find bugs

4

When	Who finds it	Who knows	Time to find the bug
Before check-in	You	1	~ minutes
During code review	Teammate (dev)	Team devs	~ hours
Manual component testing	Teammate (QA)	Whole team	~ days
Manual integration testing	Service Level QA	Team + SL	~ weeks
In production	Client	Everybody	~ weeks / months

5 of 13

Why do we test?

Use tests as specification

5

Limit number of bugs in production code

Catch defects early

Programming mistakes
Regression

6 of 13

What to test?

6

7 of 13

Goals of test automation

The addition of tests should:

Improve the quality of the system
Help us understand the system
Reduce the risks

The tests should:

Be easy to run
Be easy to verify
Be easy to write
Require minimal maintenance

7

Left

1- It helps refactoring and improving things because we’re not afraid to break something anymore

2- We have to think about the corner cases and how the system should work

3- Risks such as discovering a bug in production (worst case scenario this results in a reputation-damaging incident for the company), re-introducing a bug that was previously fixed, or introducing new bugs (because writing the tests forces to think about what the system is supposed to do)

Right

1- If they are easy to run it’s an incentive to run them, and to run them often

2- They give a green or red bar. The idea is that I can press a button to run all the tests and the bar is either green or red. Keeping the bar green is the most important thing: if we don't care about keeping the bar green then we lose the value of testing

3- Ideally they are written in the same language as the program so the extra effort is minimal

4- They need to be well written, and that’s why we’re using patterns to avoid common source of problems during the tests. If the maintenance cost is too high then it’s an incentive to just stop testing (especially as seen from a business point of view, as the test code does not make visible money and is not mandatory)

8 of 13

Goals of test automation

8

9 of 13

Tools

The xUnit family is a set of testing frameworks for different languages

NUnit
JUnit
RUnit
VbUnit

Class <-> Test class

Method <-> Several test methods

9

10 of 13

Code example: simplified French roulette

Bet on a number from 0 to 36

If your number comes up, payout is 35:1

Example: You bet $1 on 7

7 comes up -> You win $35
Otherwise -> You lose your $1

10

11 of 13

Links

11

12 of 13

13 of 13

Questions / discussions

Source

13