I have a piece of code that walks over some directories and reads some files.
I am trying to write some tests and I am struggling to find an appropriate fs mocking procedure.
All the fs access in Rust is built on top of std::fs which is a module, not a trait or any other kind of interface, so there is no real way to substitute std::fs by std::mock_fs or something like that for the tests.
Creating tempdirs and all that is fine for integration tests, but I don’t think I should be relying on local fs for unit tests.
Somebody must have seen this issue before, how do people deal with this?
You might want to try the tempfile crate:
With that you can create individual files or directories, and they will be deleted when the object goes out of scope. I think the crate also defaults to using the OS’s designated temporary directories, e.g.
/tmp/ on linux, which is usually a tmpfs/ramdisk.
Alternatively, the types from
std::fs implement several traits over which you might be able to abstract, e.g.