Is there a way to mock interface? #257
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dzvancuks
changed the title
When you say “print out results”, what sort of output do you expect? I’m asking because the nftables package is rather low-level and works directly with the wire format. Drill into the Conn.AddTable implementation, for example, to see that it directly appends to cc.messages. Do I understand correctly that you are asking for some higher-level abstraction where a high-level version of the request gets stored (e.g. the The main problem I see with this approach is that it won’t work for code that queries the rulesets to construct the changes to the rulesets. If we wanted to make it work, we’d need to either run against the system nftables (which you don’t want as it requires privileges), or we’d need to somehow simulate what nftables does, and that’s not something I want to get into.
Just to spell it out in detail to avoid any misunderstandings: nftables_test.go uses the Lines 233 to 286 in 8ffcbc2 This doesn’t require sudo; only the tests which query the system ruleset require sudo, as explained above. For now, I think if you want to ensure that you did the right nftables library calls in the right order, your best bet is to define your own interface and a recorder implementation that records the parameters for later comparison. Maybe this approach is good enough for your use-case. Or maybe you have some insight into how to generalize it so that it could work for all use-cases (despite what I outline above), in which case I’d be happy to learn more :) |
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Hi! Thanks for the hint!
this way I could compare string to string. It would be readable from UT perspective and easy to test. But I know that NFT sometimes mangles output by optimizing code. So some deviations are expected. At least approximate output in string format would also do.
I could even create mocks on my own using https://github.com/vektra/mockery. All I need is an interface for those functions.
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I can understand the appeal of this suggestion from a user perspective, but please note that the textual representation you’re describing from the We never translate from text to nftables concept or vice-versa in this Go nftables package. Adding this additional layer would be a lot of complexity.
Yes, but as I mentioned, this doesn’t work as soon as you call any functions that retrieve nftables state, unless you mock those, too. The value of such a test seems relatively low in my eyes, as you only verify that you call functions in the right order, but not that your sequence of function calls can actually configure nftables. Hence I’m not convinced that it’s worthwhile adding mock test helpers to this module.
No, you don’t need an interface in the nftables package for that. You can just define an interface yourself in your own package. In fact, in Go, interfaces should typically go into the package that uses them: https://go.dev/wiki/CodeReviewComments#interfaces |
I would like to Unit Test my NFT code. Is there a way to mock interfaces of Conn, Set, Rule and expressions? I.e. I want to apply some rules to the chain and print out results so that it could be tested against expected rules.
In current implementation I encounter problem that UT must be executed using sudo as rules are applied directly to NFT: https://github.com/google/nftables/blob/main/nftables_test.go
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