This document discusses unit testing in iOS. It defines unit testing as small pieces of code that test individual parts of a program to show they are correct. Key advantages are finding problems early, demonstrating code works, and ensuring regressions don't reoccur. The document covers the XCTest framework, writing testable code, mocks and stubs. It provides examples of writing unit tests in Xcode including for asynchronous operations and performance. Continuous integration with Xcode Server is also discussed.

1. Unit Test (iOS)
Nguyen Van Dung B, D3

2. Table of Content
1. What is unit test?.
2. What is testing for?
3. XCTest
4. Mock Object
5. Write stubs
6. Demo

3. What is unit test ?
Unit tests are small pieces of code that test the
behavior of other code
The goal of unit testing is to isolate each part of the
program and show that the individual parts are
correct

4. Advantages Of Unit test
Find problems early during develop
You can demonstrate that your code works
Modularity: Unit tests help keep you focused on
writing more modular code.
Focus: Writing tests for micro features keep you
focused on the small details.
Regression: Be sure that the bugs you fixed stay
fixed.
you’ll need unit tests to validate your refactoring.
Unit tests are great way to write better code.

5. Disadvantages of Unit Tests
More code
More to maintain : When there is more code, there is more to
maintain.
No sliver bullet : In projects with high test coverage it’s possible to
have more test code than functional code.
Takes longer: Writing tests takes time
It still is code. So it can error

6. A good unit test
Able to be fully automated
Tests a single logical concept in the system
Consistently returns the same result (no random
numbers, save those for integration tests)
Is maintainable and order-independent
Runs fast
Is Readable
Is Trustworthy

7. A Test is not unit test
talk to the database
Communicates across the network
Touch file system
Can’t not run at the same time as any of your other
unit tests.
You have to do special things to your environment
(such as editing config files) to run it.

8. Writing testable code
Define api requirements:
Write test cases as you write code
Check boundary conditions
Use negative tests
Write comprehensive test cases
Cover your bug fixs with test cases

9. When should software be tested ?

10. When should software be tested ?

11. XCTest
Xcode’s testing framework
Test case subclasses
Test method
Assertions
Integrated with Xcode
CI via xcode server and xcodebuild
Swift and Objective-C

12. XCTest Asserts

13. Xcode Test Navigator
Introduce test navigator
Writing test class and method
Run the test and see the result

14. XCTest flow
- For each class, testing starts by running class setup method
- For each test method, new instance of the class is allocated
and have same sequence above
- After last test method tearDown in class xcode will execute
class teardown method and move on to next class.

15. Test class
Subclass of XCTestCase
No header file
Has some common template method
(setUp,TearDown…)

16. Writing test method
Is an instance method of a test class
Has prefix “test”
No parameters
Return void

17. Writing test of asysnchronous
operations

18. Writing Performance Tests
A performance test takes a block of code that you
want to evaluate and runs it ten times, collecting the
average execution time and the standard deviation for
the runs
Using new api from XCTest in xcode 6 and later

19. Analyzing result

20. Mocks Object
What is mock object?
Why use Stubs ?
Don’t mock what you don’t own

21. What is mock object?
a simulated object that mimic the behavior of real
objects in controlled ways.
Create mock object to test the behavior of some other
object.
Has same interface as the real object they mimic

22. Mocks
Target communicates with the mock object, and all communication
are recorded in the mock. The test uses mock to verify that the test
passes.

23. Stubs
Returns specified result for a message, stubs can’t fail the test

24. Why use stubs?
When real object is impractical or impossible to
incorporate into a unit test
If an actual object has any following characteristis, it may
be useful to use a mock object in its place.
Object supplies non-deterministic result (current time,
current temperature)
It has states that are difficult to create or reproduce (network
error …)
It is slow (eg complete datebase,…)
It does not yet exist or may change behavior
it would have to include information and methods
exclusively for testing purposes (and not for its actual task).

25. Example Mock Object

26. Writing Stubs
 Fake a response to method calls of an object
 Use to test your code against a web service that isn’t
yet finished
Demo in project

27. UI Testing
iOS 9/OSX 10.11 or greater
Record steps,
Add assertion check if interface elements are in the
expected state
DEMO in project

28. About Continuous Integration in Xcode
Automating and streamlining the building, analyzing,
testing, archiving of App.
The goal of continuous integration is to improve
software quality
Catching problems quickly, easily, and early
Enhancing collaboration
Broadening test coverage
Generating build and test statistics over time

29. Xcode continuous integration
workflow

30. Xcode Server source code repository
interaction

31. Xcode Server activity reporting
workflow