Code Smells

Code Smells

1. "surface indication corresponding to a deeper problem in the system"

2. Where do they come from?

   • Technical Debt
   • Doing things the "fast" way

3. Types

   • Bloaters
     • Large classes
     • Long methods
     • Data Clumps
     • Long parameter list
   • OO Abusers
     • Refused Bequest
     • Switch statements
   • Change Preventers
     • Shotgun surgery
     • Divergent Change
   • Dispensables
     • Duplicated code
     • Lazy Class
     • Data class
   • Couplers
     • Feature envy
     • Inappropriate Intimacy
     • Middle man

4. Code smells help us find the problem

   • Refactoring
     • Incremental changes that improve design without changing functionality
     • Behavior Preserving
     • Why Refactor?
       • Needs improvement
       • Messy code
       • Requirements change
     • Types
       • Rename
       • Collapse Hierarchy
       • Consolidate/Decompose conditional
       • Extract Method
       • Extract class
     • Tools
       • IDE's have many built-in tools to help us refactor
     • When to refactor?
       • adding a feature
       • code review
       • fixing a bug
     • Refactoring is a part of the TDD cycle
       • Test-Driven Development
         • Why TDD?
           • Huge expenses with bugs (607 billion in 2020)
         • Verification Approaches
           • Dynamic Verification
             • Try to make it fail!
             • Executing code to verify expected behavior
             • Testing Stages
               • Developer's Testing
                 • Alpha Testing
                   • Beta Testing
                     • Product Release
               • Within organization
               • Outside organization
           • Static Verification
             • Finding potential issues
             • No execution
           • Inspections/Reviews/Walkthroughs
             • Inspection -- moderator + formal
             • Review -- peers + less formal
             • Walkthrough -- author + informal
           • Formal Verification
             • Time-consuming and expensive
             • For high stakes scenarios
         • Testing Techniques
           • Opaque Box: assess from outside
           • Clear Box: looking under the hood
         • Writing tests before the code
           • Red, Green, Refactor
             • Make it fail, make it work, make it better