Refactoring by Leveraging Your Tests with TypeScript & Jest
This course focuses on the Refactor step in TDD, teaching developers to spot code smells and resolve them through refactoring. Using real-world examples, you'll identify common issues, apply refactoring techniques, and ensure functionality is preserved with existing tests.
Lessons and practices
Lesson 1: Eliminating Duplicated Code: Extract Functions and Refactor Magic Numbers
Refactor Duplicated Code in the Tests
Refactor Tests using Parameterization
Extract Function: calculateItemCost
Refactor duplication between calculate functions
Refactor Magic Numbers to Constants
Lesson 2: Long Method Refactoring: Extract Method Technique
Extract user validation logic
Extracting validation into validator classes
Extract data normalization code
Setting our sights on the DataStore
Extract Result Type
Lesson 3: Long Parameter List: Introduce Parameter Object
Streamline Parameters with a Parameter Object
Introduce a CoursePolicy parameter object
Re-order parameters for cohesion
Provide defaults for most parameters
Lesson 4: Feature Envy: Move Method Refactoring with TDD
Extract StudentGrade Logic
Refactor: MoveMethod calculateFinalGrade
Eliminate the GradeAnalyzer
Eliminate Feature Envy from the Student
Lesson 5: Large Class: Extract Class
Extract a CartItemCollection
Extract the PriceCalculator class
Extract a DiscountCalculator class
Write Tests for Extracted Classes
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