C++ Unit testingThe good, the bad and the uglyDror Helper | @dhelper | http://helpercode.com

Consultant @CodeValue

Developing software since 2002Clean Coder & Test Driven Developer

Pluralsight authorhttps://www.pluralsight.com/authors/dror-helper

B: http://helpercode.comT: @dhelper

About.ME

An ode to C++

Multi-paradigm Performance & Speed Truly multi-platform Plays well with others

Extendible and powerful Low level programmingMy compiler compiled

your compiler’s compiler

“C makes it easy to shoot yourself in the foot;

C++ makes it harder, but when you do it blows your whole leg off.”Bjarne Stroustrup

Avoid stupid bugs

Early feedbackAvoid

Regression

Write Sustainable, manageable

code

Route to modular OO

design

In code documentation

Have you tried unit testing your code?

Definition: Unit Test (by me)

A method (code)

that tests specific functionality,

Has clear pass/fail criteria

and runs in isolation

This is a unit test (GTest)

TEST(MovieTests, WhatWouldTucoDo)

{

Charcter tuco;

tuco.SetHaveToShoot(true);

ASSERT_FALSE(tuco.GetTalk());

}

What you’ll need

Developer’s Machine

• Unit testing framework• Mocking framework• Code coverage tool• Other (IDE, Refactoring tools)

Continuous Integration

• CI Server• Build Agent(s)

Unit testing framework capabilities

Tests &

Fixtures

Assertio

ns

Test

Runners

C++ Unit Testing Frameworks

The Good

• Many choices• Many Styles

The Bad

• Documentation may vary• Not all maintained

The Ugly

• Deployment• No Reflection…

* at least until C++/2020

C++ Unit Testing Frameworks

GTest

MSTest

Catch

CppUnit

Boost.Test

DocTest

lest

xUnit++

Mettle

A Short, incomplete list…

Multiple asserts

• Lose information• Complex tests

One assert per test

• Writing many tests for the same scenario

• See Above

The multiple assertion dilemma

Innovation in C++

Enabling readable and maintainable tests

• Failures without exceptions

• Better failure messages

• Single, powerful assert

• Rethinking test fixture - Sections

16

What is a “Mock”?

“mock objects are simulated objects that mimic the behavior of real objects in controlled ways”

[From Wikipedia]

I prefer to call them “Fakes”

Mocking frameworks responsibilities

1. Create Fake/Mock objects

2. Set behavior on fakes

3. Verify that methods were called

C++ Mocking Frameworks

The Good

• C++ has mocking frameworks

The Bad

• I meant a framework (at least until recently)• Beware of dead projects

The Ugly

• Most one step better than hand rolled mocks• Most are not AAA compliant

C++ Mocking Frameworks

GMock

Trompeloeil

HippoMocks

FakeIt

*Based on my own experience

Don’t use obsolete tools!

1. Check when was the last commit!

2. How extensive is the documentation

C++ is changing and so should your testing framework

C++ Development in Windows

• Multi-platform – develop on windows, compile to run everywhere

• Remote debug/run on Linux (VS2017)

• Use test runner (or develop your own)

• Code coverage support

How to choose your unit testing tools

Multi-platform vs. mono-platform

Ease of use

What happens when test fails

Integration points

Runner Support

Ease of deployment

Personal taste

IN THIS WORLD THERE’S

TWO TYPESOF PEOPLE MY FRIEND.THOSE WITH UNIT TESTSAND THOSE WHO BLAME.

WRITE UNIT TESTS!

Thank youDror Helper | @dhelper | http://helpercode.com