Testing Date Calculations in TypeScript: A Comprehensive Approach to Unit Testing
Jugleni Krinski
?? Em busca de novas oportunidades de Trabalho Remoto | ?? Apaixonado por Tecnologia | ?? 20+ Anos de Experiência | ?? Especialista em Cloud | ?? Pai Orgulhoso
Abstract
This article presents a robust solution for testing date calculations in TypeScript applications, addressing common challenges such as timezones, Date object mocking, and type safety. The solution was developed through collaboration between developers and AI, demonstrating how different perspectives can contribute to solving complex problems.
Introduction
- Complexity of date-related testing
- Timezone challenges
- Type safety requirements
- Importance of reliable tests
- QuickQuote application
- Need for precise date calculations
- TypeScript type safety requirements
Technical Challenges
- Preserving static methods
- Cross-timezone consistency
- TypeScript type safety
- Day transitions
- Month transitions
- Leap years
- Different times of day
Developed Solution
```typescript
const calculateDaysUntilClosing = (closingDateStr: string): number => {
const now = new Date();
const target = new Date(closingDateStr);
const currentDate = new Date(
Date.UTC(
now.getUTCFullYear(),
now.getUTCMonth(),
now.getUTCDate()
)
);
const targetDate = new Date(
Date.UTC(
target.getUTCFullYear(),
target.getUTCMonth(),
target.getUTCDate()
)
);
const MS_PER_DAY = 24 60 60 * 1000;
const diffTime = targetDate.getTime() - currentDate.getTime();
const diffDays = Math.round(diffTime / MS_PER_DAY);
return Math.max(0, diffDays);
};
```
```typescript
interface DateTestCase {
current: string;
target: string;
expected: number;
description: string;
}
const transitionCases: DateTestCase[] = [
{
current: '2024-01-01',
target: '2024-01-02',
expected: 1,
description: 'next day'
},
// ... other cases
];
test.each(transitionCases)(
'given current date $current and target date $target, should return $expected day(s) ($description)',
({ current, target, expected }) => {
// ... test implementation
}
);
```
Results and Benefits
- Complete type safety
- Reliable and consistent tests
领英推荐
- Comprehensive edge case coverage
- Improved maintainability
- Reduction in date-related bugs
- Increased test confidence
- Safer and typed codebase
- Better documentation
- Importance of collaboration
- Value of development iteration
- Need for comprehensive testing
- Benefits of strong typing
Conclusion
The developed solution demonstrates how collaboration between developers and AI can result in robust solutions for complex software development problems.
Acknowledgments
- Jugleni Krinski and team
- Anthropic (Claude)
- Development community
Technical Details
All code and examples are available at:
- GitHub: github.com/jugleni
- Medium: medium.com/jugleni
- LinkedIn: linkedin.com/in/jugleni
- Blog: jugleni.com
References
- TypeScript Documentation
- Jest Documentation
- Articles on date testing
- Next.js Testing Best Practices
- OpenAI collaboration with the DALL-E 3 model to generate the banner for this post