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That's interesting because I think the exact opposite. For dynamically typed languages I think it's more valuable to have end-to-end tests to make sure that th

by dudul 6y ago

That's interesting because I think the exact opposite. For dynamically typed languages I think it's more valuable to have end-to-end tests to make sure that the whole pipeline works correctly. I want to validate that all the call sites for function F are passing an int, as intended, as opposed to a string. For statically typed languages, I already know that all call sites for F are passing an int. So I want to unit test all small parts of the pipeline, in isolation, to make sure I easily spot which part doesn't follow its contract. If a function F uses a function G for something, I'm gonna unit test F and make sure it does behave correctly for all possible returns from G, and that's it.

morelisp 6y ago
Typed language also make it possible to exhaustively test inputs. For functions that only have a few dozen or hundred possible inputs we can exhaustively test every single case (even millions/billions as part of a slow suite). For looser languages, maybe the function takes a fuzzy notion of "a number" - OK, do I need to try the string "12"? What about "012"? What about "12.0" or " 12" or "\n12"?
bluGill 6y ago
Dynamically types languages are just plane unsuitable for the type of large project where you need to break your end to tests down into unit tests. If you have a trivial program (under 100,000 lines of code or so), your end to end tests won't take that long to run if you take care, you will never be able to maintain that much in a dynamic language just because change becomes so hard without static types.
- tcbasche 6y ago
  That's not really true, change is incredibly _easy_ without static types. I've worked an a few large projects now all in Python or JS where the test time has never really been an issue, nor has the ability to make changes. I'd say it's not really the language, but rather the abuse of it. The same goes for any project in any programming language.

by dudul 6y ago

morelisp 6y ago

Typed language also make it possible to exhaustively test inputs. For functions that only have a few dozen or hundred possible inputs we can exhaustively test every single case (even millions/billions as part of a slow suite). For looser languages, maybe the function takes a fuzzy notion of "a number" - OK, do I need to try the string "12"? What about "012"? What about "12.0" or " 12" or "\n12"?

bluGill 6y ago

Dynamically types languages are just plane unsuitable for the type of large project where you need to break your end to tests down into unit tests. If you have a trivial program (under 100,000 lines of code or so), your end to end tests won't take that long to run if you take care, you will never be able to maintain that much in a dynamic language just because change becomes so hard without static types.

tcbasche 6y ago
That's not really true, change is incredibly _easy_ without static types. I've worked an a few large projects now all in Python or JS where the test time has never really been an issue, nor has the ability to make changes. I'd say it's not really the language, but rather the abuse of it. The same goes for any project in any programming language.