Fundamental Knowledge

Object-Oriented Programming

• Encapsulation
• Composition, inheritance, and delegation
• Polymorphism
• Objects and classes
• Open recursion

Source: Wikipedia

Code Refactoring

• Target
  • Production Code
  • Test Code
  • Between Production and Test Code
• Techniques
  • More Abstraction
    • Field Encapsulation
    • Type Generialization
    • Replace Conditional with Polymorphism
  • Breaking Code Apart
    • Extract Class
    • Extract Method
  • Improving Names and Location
    • Move Methods or Move Field
    • Rename Method or Rename Field
    • Pull Up, move to a superclass
    • Push Down, move to a subclass

Source: Wikipedia

Design Pattern

Here are most frequenly-used patterns as specified by Kerem Koseoglu in his book ABAP to the Future.

• Architectural Patterns
  • MVC, used all the time
• Creational Patterns
  • Factory and builder to create new objects in a centralized point
  • Singleton and multiton to prevent creation of multiple instances of the same objectrespectively
  • Lazy initialization for overall performance improvement
• Structural
  • Facade to make the life of other developers easier
  • Decorator to modify an object or dataset by multiple classes
• Behavioral
  • Template method to prevent algorithm duplication among similar classes
  • Strategy to make algorithms interchangeable
  • Observer to make objects communicate without making them interdependent
  • Visitor to extend the functionality of classes without modifying legacy code

Essential Knowledge

Writing Unit Test

• F.I.R.S.T Principles
  • Fast
  • Independent
  • Repeatable
  • Self-Validating
  • Thorough and Timely
• Testing Frameworks
• 3A’s Pattern
  • Arrange
  • Act
  • Assert

Design Principles

• KISS: Keep it simple, stupid
• DRY: Don’t repeat yourself
• YAGNI: You aren’t gonna need it
• SOLID (Motivational Posters)
  • Single Responsibility Principle (SRP)
  • Open Closed Principle (OCP)
  • Liskov Substitution Principle (LSP)
  • Interface Segregation Principle (ISP)
  • Dependency Inversion Principle (DIP)
    • Inversion of Control (IoC)
      • Dependency Injection (DI)
        • Constructor injection
        • Parameter injection
        • Setter injection
        • Interface injection

Test Double

• Types
  • Dummy
  • Stub
  • Mock
  • Spy
  • Fake
• Frameworks
  • SAP ABAP
    • ABAP Test Double Framework (ATDF)
    • ABAP CDS Test Double Framework
  • Java
    • Stubby4j
    • dbUnit
    • WireMock