Writing testable codeAndrew Chaa, Team Magnum

What to test ?

Only Business Logic !

Database Engine

Business

UI

Only public methods And public properties

Test Business Logic

Testable Coding

Anti-Pattern

Smart UI

Very hard to test in Asp.Net webform

Mixed with .Net version specific code

UI Code

So, let’s put the obese UI on a diet

Engine

Business

UI

Engine

Business

UI

Only control execution flows Business Agnostic

◦ UI code should not change when business logic changes

Simple UI

Try not to write more than 10 lines of code in any given method◦ Of course, it’s not for its own sake. If it has more

than 10 lines, it seems to have some business logic.

Possibly, program to interface, not concrete class◦ ICandidateStatRepository repo = new CandidateStatKeytermRepository() ◦ or ◦ ICandidateStatRepository repo = new CandidateStatLocationRepository()

◦ repo.GetCandidateStat(…)

Practically, in UI

Business gets smart

Database operation

Inherits BaseBusinessClass

Create a domain object from data◦ Entity / value objects

Service Class

Does not inherit BaseBusinessClass

Often created from Service class

Add business logic on top of available data◦ public string FullName { ◦ get { return FirstName + “ “ + LastName; }◦ }

Domain Object

Interface is more flexible than inheritance

UI can program to interface

◦ IMarketing _eloquaTag◦ _eloquaTag = new EloquaTagBlank(); // BaseWebPage◦ _eloquaTag = new EloquaTagDefault(true); // SiteHome◦ _eloquaTag = new EloquaTagDefault(); // BaseRecruiterPage◦ _eloquaTag = new EloquaTagDefault(); // LoginNewUser

Let’s use Interface

Different implementation

◦ IMarketing _eloquaTag◦ _eloquaTag = new EloquaTagBlank(); // BaseWebPage◦ _eloquaTag = new EloquaTagDefault(true); // SiteHome◦ _eloquaTag = new EloquaTagDefault(); // BaseRecruiterPage◦ _eloquaTag = new EloquaTagDefault(); // LoginNewUser

Same method

◦ _eloquaTag.GetTag()

Program to Interface

Just make the code in a better state than what you found it in

◦ Shorter UI code◦ Extract Method◦ Use Domain object, if possible

What about legacy?

Make your code testable by

Try no more than 10 lines of code in UI methods

Program to an interface

Use Domain business objects

In summary