144: Gary Bernhardt - TypeScript and Testing

Topics include:

• Why Gary decided to write Execute Program as a full-stack TypeScript application instead of using a Ruby or Python backend like he may have traditionally
• Do you actually have to write less tests if you have a good type system?
• What does a good type system give you that tests can't give you?
• Using io-ts to type check incoming data
• How to think about structuring your code to best take advantage of the benefits your type system gives you and minimize the need to write tests
• Pushing conditional logic to the core of your system to reduce the number of tests you need to write at the edges
• The correlation between type errors and behavioral bugs, and how a type system can help you catch mistakes you don't think to test for
• Do type errors signal that you're missing a test?
• Structural vs. nominal type systems, and the benefits of structural type systems like used by TypeScript and Go
• Best practices for type-checking within a function in a structural type system like TypeScript
• The power of supporting literal types like true or "active" in addition to traditional types

Links:

• Destroy All Software
• Execute Program
• TypeScript
• "Are tests necessary in TypeScript?"
• io-ts
• TypeScript course on Execute Program
• Gary's tweet about unions with literal types

Supporting the show:
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If you do want to support the show, the best way to do it is to purchase one of my products:

• Tailwind UI, a collection of professionally designed, fully responsive HTML components built with Tailwind CSS.
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• Test-Driven Laravel, a massive video course on designing robust Laravel applications with TDD. Learn how to build a real-world application from scratch without writing a single line of untested code.
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