[doublesCs]

> Test against the same dependencies that exist in production.

Interesting. I said this at my work recently and I got a condescending explanation about how production things are production, we don't touch them. If we need stuff for development, those are dev things.

I now think that whether this is or isn't a good idea depends on specifics. Most often than not, I think it makes sense.

[detaro]

I think parent means test against the same code, not against the same instance as production. Tests don't get to talk to the production database, but should use the same database software, deployed as similarly as possible, as production does. Against test/demo versions of APIs if possible. ...

[tmountain]

With an identical schema to boot.

[devit]

I don't mean testing against the production instance, but rather against an instance configured like the production instance, except for being scaled/sized appropriately for the testing data and workload instead of the production one.

It's also possible to test against live production instances and data itself (mostly useful for performance optimization work and testing), although that's more of an ad-hoc process and some kinds of tests are not possible because the actual data there is arbitrary. Also, those tests, if not used for development, might be better expressed as self-checks done on system start and monitoring systems.

[tyurok]

That's where "works on my machine" comes from.

The further you steer dev environments from production, the more you'll have these kinds of issues.

Would you mind expanding on their explanation? The way you described doesn't sound like an argument at all.