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Fakes > Mocks! Post: https://tyrrrz.me/blog/fakes-over-mocks https://tyrrrz.me/blog/fakes-over-mocks Previous HN Discussion on the above post: https://news.yc

Fakes > Mocks! Post: https://tyrrrz.me/blog/fakes-over-mocks https://tyrrrz.me/blog/fakes-over-mocks Previous HN Discussion on the above post: https://news.ycombinator.com/item?id=24770954 https://news.ycombinator.com/item?id=24770954 This does require dependency injection (DI), and my hot take is that manual DI > framework magic. Sure it's a little extra code writing, but folks should optimize for reading code, and some of the frameworks out there have a lot of complex concepts for DI (For example dagger is a popular DI framework for JVM, and the dev-guide has a lot of stuff in it, which feels like a lot to learn for what it's providing: https://dagger.dev/dev-guide/ https://dagger.dev/dev-guide/, no knock against dagger, I've ran into this with other DI frameworks too!)

sethammons 4y ago
Glad to see one more article on fakes > mocks. Here's mine that is not quite as good and focuses on Go from four or so years ago: https://sendgrid.com/blog/when-writing-unit-tests-dont-use-mocks/ https://sendgrid.com/blog/when-writing-unit-tests-dont-use-m...
williamcotton 4y ago
One approach I’ve found useful is publishing a test suite as a module for use in these kind of “fakes”. For example, a file system blob store that passes the same test suite as an S3 blob store can be used as a reliable fake. https://github.com/maxogden/abstract-blob-store https://github.com/maxogden/abstract-blob-store
leidenfrost 4y ago
Interesting. However, I find mocks useful when I try to replicate error handling in case of unexpected exceptions. How do I replicate that with a Fake? A flag for error triggering?
- sethammons 4y ago
  In Go, I create a struct with two properties: err and value. When err is set, it returns that, else returns the value. In the test, I create the fake and set its err to whatever and then verify handling. As needed, you can add properties and add a delay to the response if set.
SixDouble5321 4y ago
Ah yes, the test code that you have to write test code for. That's just what I wanted. I imagine there are some situations where the maintenance cost is better after the upfront investment. Seems like betting against one's self to me.

sethammons 4y ago

Glad to see one more article on fakes > mocks. Here's mine that is not quite as good and focuses on Go from four or so years ago: https://sendgrid.com/blog/when-writing-unit-tests-dont-use-mocks/ https://sendgrid.com/blog/when-writing-unit-tests-dont-use-m...

williamcotton 4y ago

One approach I’ve found useful is publishing a test suite as a module for use in these kind of “fakes”. For example, a file system blob store that passes the same test suite as an S3 blob store can be used as a reliable fake. https://github.com/maxogden/abstract-blob-store https://github.com/maxogden/abstract-blob-store

leidenfrost 4y ago

Interesting. However, I find mocks useful when I try to replicate error handling in case of unexpected exceptions. How do I replicate that with a Fake? A flag for error triggering?

sethammons 4y ago
In Go, I create a struct with two properties: err and value. When err is set, it returns that, else returns the value. In the test, I create the fake and set its err to whatever and then verify handling. As needed, you can add properties and add a delay to the response if set.

SixDouble5321 4y ago

Ah yes, the test code that you have to write test code for. That's just what I wanted. I imagine there are some situations where the maintenance cost is better after the upfront investment. Seems like betting against one's self to me.