Advanced unit testing – real life examples and mistakes

Advanced Unit Testing – real life
examples and mistakes
Milan Vukoje
www.Vukoje.NET
vukoje@gmail.com

 Goals & Dangers
 Real life examples
 VS & TFS tips
 Best Practices
 Smells
Themes

 Improved quality
 SUT understanding
 Reduced risk
 Easy creation/maintaining
 Easy run
Goals of UT

 Additional costs
 Slowing down production code changing
 Losing tests in logic migration
 Tests take too long to write
 Poor Organization /Maintenance problems
Dangers of UT

Soprex Core Application (SCA)
DB
Win Web
UI
BL
DAL
SCRUM
Refactoring
Coding Standard
Code Review

 DB problems
 Persistent
 Slow
 Shared
 Complicated
Persistent fixture
DB
Win Web
UI
BL
DAL

 Shared Fixture + Partial cleanup
 Cleanup in Finally blocks
SCA.DAL – Cleanup Strategy

 Not treating tests as production code
 Do not duplicate test code
 Creation and Finder methods
 Custom Assertations
 Parameterized tests
 Test Run War
SCA.DAL
DB
Win Web
UI
BL
DAL

 Generic CRUD tests
 Uses generated values
 Tries to break constraints
 Insert nulls
 Max values
 Mini integration tests
 Great for detecting DB schema mismatch
SCA.BLTester
BL
DAL
DB
BLTester

 Isolated Business Logic testing
 Mini Integration vs. FakeDB
 QueryObject + DataTable = FakeDB
 SCA.MockHelper
 Setup with Reflection
 Factory would be better choice
SCA.FakeDB
BL
DAL
DB
Fake DB

 Avoid Fragile Tests (To Pass or Not to Pass)
 Test Run War
 Non- deterministic tests
 Interacting tests
 Don’t use DB accident/random records
 When there is a way of testing w/o the DB,
test w/o DB.
 SCA.AppTranslation
 Testing w/o DB
 And than back to DB…
Lessons Learned
DB
Win Web
UI
BL
DAL

 Very important
 Bug can be very expensive
 Huge num. of combinations
 Integration Test failure
SCA.PriceCalculator
DB
Price Calculator
BL
DAL
Price
Request
Price

 Price Manager
 Simple calculations
 Easily tested with FakeDB
 Highly optimized cache
 Price Calculator
 Main algorithm
 Easily tested with Stub
 Concurrency control
Stub to the rescue!
DB
Price Calculator
BL
DAL
Price
Request
Price
Price Manager

When you have a new hammer, everything looks like a nail!
 Calculator example
 Use the Front Door First
 Guard Assert Example
Overdoing mocking

Use Case testing
DB
Win Web
UI
BL
DAL

 Model – View – Problem
 Presenter testing problems
 Not Isolated (GUI)
 Hard Indirect output control
 Testing Mocks
 Solution
 View Stub
 Setup Methods
SCA.UI
DB
Win Web
UI
BL
DAL

 Design for Testability
 Just a bit design upfront
 Be ware of the code smells
 Keep It Simple and Stupid (KISS)
 Always know what you are testing
Lessons learned
DB
Win Web
UI
BL
DAL

 Minimize untestable code
 Auto-synchronization
 Helper classes
 Indirect GUI control
 Don’t test GUI
 Also… buy GUI controls 
SCA.GUI
DB
Win Web
UI
BL
DAL

 Avoid Accessors
 Do not generate unit tests
 Avoid assertion roulette
 Use Assert class properly
Visual Studio tips

 Test Run & Build Policy
 Check-in Build & Build With Tests
 Nightly build with Code Analysis and Tests
 Build Error Notification
TFS - Continues Integration with

 Write the Tests First
 Communicate Intent
 Do not modify the SUT
 Keep Tests Independent
 Minimize Test Overlap
 Keep Test Logic Out of Production Code
 Verify One Condition per Test
More best practices…

 Design
 Long setup
 Hard to test code
 Slow tests
 Test logic in production
 Code
 Obscure test
 High test maintenance
 Conditional test logic
 Duplication
 Frequent Debugging
 Production bugs
Smells

 UT have grate benefits
 UT comes with dangers
 Watch the smells?
 Follow best practices
Summary

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Thanks!
Milan Vukoje
www.Vukoje.NET
vukoje@gmail.com

Advanced unit testing – real life examples and mistakes

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Advanced unit testing – real life examples and mistakes