Question

I am working on a module that supplies methods for navigating directories and manipulating files. Basically it will be a combination of the Dir and File classes, with options specific to the needs of a project I’m working on.

Right now I have started writing tests for some of these methods and things are getting messy.

Example

One of the methods I have is a tree function that returns a hash of files and folders where you can pass options like tree(only: 'folders', limit: 3). In order to test that it only goes down 3 levels, I would have to have 4+ subfolders with dummy files in them.

The Problem

Right now I’m testing on folders outside the project since the subfolders are already there, but I want to move away from this, especially considering the implausibility of testing on system files once I start testing methods equivalent to rm -rf (as well as the lack of portability).

I’m starting to think that I need to create a "lab rat" type folder that I do all my "experiments" on, but I have no clue how to approach creating it.

• Do I create a function that creates the files?
• Do I pull files and folders from another location?
• Do I use some sort of "lorem ipsum" generator for file structures?
• Do I make all these files and folders manually(ugh)?
• Do I just mock and stub the hell out of everything and not actually create/delete the files and folders?(I don’t see this happening)

So…

How would someone normally approach testing excessive amounts of file and folder manipulation?

Answer 1

I don’t think you want to use mocks/stubs. The file system of your OS should be well tested and fast, so the benefit of mocks/stubs is minimal. Creating a mock/stub system increases the complexity without much benefit.

Here’s my answers:

Do I create a function that creates the files?

Yes. You can create tests for these functions to make sure that they are correct. Instead of calling Dir and File, write helper functions that make the code simple and readable. Maybe you can share the helper functions between the source/test code…

Do I pull files and folders from another location?

Not sure what this is for…

Do I use some sort of “lorem ipsum” generator for file structures?

Yes, if you mean create functions that generate file structures.

Do I make all these files and folders manually(ugh)?
No.

Do I just mock and stub the hell out of everything and not actually create/delete the files and folders?(I don’t see this happening)
No. One benefit of creating files/directories is that you can manually check what is going on and not be 100% dependent on the tests. This is actually a good approach because without it there could be a bug where both the source code and test code is not doing what you expect, but you wouldn’t know because everything seems to be working.