5 ms·

I have tried to evangelize unit testing at each company I've worked at and most engineers struggle with two things. The first is getting over the hurdle of tru

by 6DM 3y ago

I have tried to evangelize unit testing at each company I've worked at and most engineers struggle with two things. The first is getting over the hurdle of trusting that a unit test is good enough, a lot of them only trust an end-to-end test which are usually very brittle. The second reason is, I think, a lot of them don't know how to systematically breakdown test into pieces to validate e.g. I'll do a test for null, then a separate test for something else _assuming_ not null because I've already written a test for that. The best way I've been able to get buy-in for unit testing is giving a crash course on a new structure that has a test suite per function under test. This allows for a much lower loc per test that's much easier to understand. When they're ready I'll give tips on how to get the most of their tests with things like, boundary value analysis, better mocking, IoC for things like date time, etc.

feoren 3y ago
> I'll do a test for null, then a separate test for something else _assuming_ not null because I've already written a test for that. Honestly, this pedantry around "unit tests must only test one thing" is counter-productive. Just test as many things as you can at once; it's fine. Most tests should not be failing. Yes, it's slightly less annoying to get 2 failed tests instead of 1 fail that you fix and then another fail from that same test. But it's way more annoying to have to duplicate entire test setups to have one that checks null and another that checks even numbers and another that checks odd numbers and another that checks near-overflow numbers, etc. The latter will result in people resting writing unit tests at all, which is exactly what you've found. If people are resisting writing unit tests, make writing unit tests easier. Those silly rules do the opposite.
- 6DM 3y ago
  Just to clarify, I am not advocating for tests to only test one thing, rather that after you have tested for one scenario you don't need to rehash it again in another test. Breaking a test down helps to clarify what you're testing and helps to prevent 80 loc unit tests. When I test for multiple things, I look for the equivalent of nunit's assert.multiple in the language that I'm in. The approach I advocate for typically simplifies testing multiple scenarios with clear objectives and tends to make it easier when it comes time to refactor/fix/or just delete a no longer needed unit test. The difference I find, is that now you know why, vs having to figure out why.
MoreQARespect 3y ago
I've evangelized against unit testing at most companies I work at, except in one specific circumstance. That circumstance is complex logic in stateless code behind a stable API where unit testing is fine. I find this usually represents between 5-30% of most code bases. The idea that unit testing should be the default go to test I find to be horrifying. I find that unit test believers struggle with the following: 1) The idea that test realism might actually matter more than test speed. 2) The idea that if the code is "hard to unit test" that it is not necessarily better for the code to adapt to the unit test. In general it's less risky to adapt the test to the code than it is the code to the test (i.e. by introducing DI). It seems to be tied up with some sort of idea that unit testability/DI just makes code inherently better. 3) The idea that integration tests are naturally flaky. They're not. Flakiness is caused by inadequate control over the environment and/or non-deterministic code. Both are fixable if you have the engineering chops. 4) The idea that test distributions should conform to arbitrary shapes for reasons that are more about "because google considered integration tests to be naturally flaky". 5) Dogma (e.g. uncle bob or rainsberger's advice) vs. the idea that tests are investment that should pay dividends and to design them according to the projected investment payoff rather than to fit some kind of "ideal".
- 6DM 3y ago
  Well, I don't regard unit tests as the one true way. I don't enforce people on my team do it my way. When I get compliments on my work, I tend to elaborate and spread my approach. That's what I mean by evangelize, not necessarily advocating for a specific criteria to be met. I find that integration tests are usually are flaky, its my personal experience. In fact, at my company, we just decided to completely turn them off because they fail for many reasons and the usual fix is to adjust the test. If you have had a lot of success with them, great. Just for the record, I am not anti-integration or end-to-end test. I think they have a place and just like unit tests shouldn't be the default, neither should they. Here are the two most common scenarios where I find integration (usually end-to-end called integration) tests become flaky: 1) DateTime, some part of business logic relies on the current date or time and it wasn't accounted for. 2) Data changes, got deleted, it expired, etc. and the test did not first create everything it needed before running the test. Regarding your points, 1) "realism" that is what I referred to as trusting that a unit test is good enough. If it didn't go all the way to the database and back did it test your system? In my personal work, I find that pulling the data from a database and supplying it with a mock are the same thing. So it's not only real enough for me, but better because I can simulate all kinds of scenarios that wouldn't be possible in true end-to-end tests. 2) These days the only code that's hard to test is from people that are strictly enforcing OOP. Just like any approach in programming, it will have it's pros and cons. I rarely go down that route, so testing isn't usually difficult for me. 3) It's just been my personal experience. Like I said, I'm not anti-integration tests, but I don't write very many of them. 4) I didn't refer to google, just my personal industry experience. 5) Enforcing ideal is a waste of time in programming. People only care about what they see when it ships. I just ship better quality code when I unit test my business logic. Some engineers benefit from it, some harm themselves in confusion, not much I can do about it. Most of this is my personal experience, no knock against anyone and I don't force my ideals on anybody. I happily share what and why things work for me. I gradually introduce my own learning over time as I am asked questions and don't seek to enforce anything. Happy coding!

by 6DM 3y ago

feoren 3y ago

> I'll do a test for null, then a separate test for something else _assuming_ not null because I've already written a test for that. Honestly, this pedantry around "unit tests must only test one thing" is counter-productive. Just test as many things as you can at once; it's fine. Most tests should not be failing. Yes, it's slightly less annoying to get 2 failed tests instead of 1 fail that you fix and then another fail from that same test. But it's way more annoying to have to duplicate entire test setups to have one that checks null and another that checks even numbers and another that checks odd numbers and another that checks near-overflow numbers, etc. The latter will result in people resting writing unit tests at all, which is exactly what you've found. If people are resisting writing unit tests, make writing unit tests easier. Those silly rules do the opposite.

6DM 3y ago
Just to clarify, I am not advocating for tests to only test one thing, rather that after you have tested for one scenario you don't need to rehash it again in another test. Breaking a test down helps to clarify what you're testing and helps to prevent 80 loc unit tests. When I test for multiple things, I look for the equivalent of nunit's assert.multiple in the language that I'm in. The approach I advocate for typically simplifies testing multiple scenarios with clear objectives and tends to make it easier when it comes time to refactor/fix/or just delete a no longer needed unit test. The difference I find, is that now you know why, vs having to figure out why.

MoreQARespect 3y ago

I've evangelized against unit testing at most companies I work at, except in one specific circumstance. That circumstance is complex logic in stateless code behind a stable API where unit testing is fine. I find this usually represents between 5-30% of most code bases. The idea that unit testing should be the default go to test I find to be horrifying. I find that unit test believers struggle with the following: 1) The idea that test realism might actually matter more than test speed. 2) The idea that if the code is "hard to unit test" that it is not necessarily better for the code to adapt to the unit test. In general it's less risky to adapt the test to the code than it is the code to the test (i.e. by introducing DI). It seems to be tied up with some sort of idea that unit testability/DI just makes code inherently better. 3) The idea that integration tests are naturally flaky. They're not. Flakiness is caused by inadequate control over the environment and/or non-deterministic code. Both are fixable if you have the engineering chops. 4) The idea that test distributions should conform to arbitrary shapes for reasons that are more about "because google considered integration tests to be naturally flaky". 5) Dogma (e.g. uncle bob or rainsberger's advice) vs. the idea that tests are investment that should pay dividends and to design them according to the projected investment payoff rather than to fit some kind of "ideal".

6DM 3y ago
Well, I don't regard unit tests as the one true way. I don't enforce people on my team do it my way. When I get compliments on my work, I tend to elaborate and spread my approach. That's what I mean by evangelize, not necessarily advocating for a specific criteria to be met. I find that integration tests are usually are flaky, its my personal experience. In fact, at my company, we just decided to completely turn them off because they fail for many reasons and the usual fix is to adjust the test. If you have had a lot of success with them, great. Just for the record, I am not anti-integration or end-to-end test. I think they have a place and just like unit tests shouldn't be the default, neither should they. Here are the two most common scenarios where I find integration (usually end-to-end called integration) tests become flaky: 1) DateTime, some part of business logic relies on the current date or time and it wasn't accounted for. 2) Data changes, got deleted, it expired, etc. and the test did not first create everything it needed before running the test. Regarding your points, 1) "realism" that is what I referred to as trusting that a unit test is good enough. If it didn't go all the way to the database and back did it test your system? In my personal work, I find that pulling the data from a database and supplying it with a mock are the same thing. So it's not only real enough for me, but better because I can simulate all kinds of scenarios that wouldn't be possible in true end-to-end tests. 2) These days the only code that's hard to test is from people that are strictly enforcing OOP. Just like any approach in programming, it will have it's pros and cons. I rarely go down that route, so testing isn't usually difficult for me. 3) It's just been my personal experience. Like I said, I'm not anti-integration tests, but I don't write very many of them. 4) I didn't refer to google, just my personal industry experience. 5) Enforcing ideal is a waste of time in programming. People only care about what they see when it ships. I just ship better quality code when I unit test my business logic. Some engineers benefit from it, some harm themselves in confusion, not much I can do about it. Most of this is my personal experience, no knock against anyone and I don't force my ideals on anybody. I happily share what and why things work for me. I gradually introduce my own learning over time as I am asked questions and don't seek to enforce anything. Happy coding!