Read file from relative path with different callers

Issue

I’m trying to read from a file in my project’s directory.

My problem is, that depending on the caller, the path changes. The caller changes, because I want to unit test this code and the caller is not Main.go anymore.

This is what my project structure looks like:

Project Structure

The code where I try to access specialChars.txt from looks like this:

func RemoveSpecialChars(word string) string {
    file, err := ioutil.ReadFile("wordlists/specialChars.txt")
    [...]
}

This code works for the start from Main.go but not for the start from CleanupUtil_test.go. To get it working from the test I would need file, err := ioutil.ReadFile("../wordlists/specialChars.txt")

I found answers like this one: https://stackoverflow.com/a/32163888/2837489
_, filename, _, ok := runtime.Caller(0) which is obviously also dependent on the caller.

Is it possible to get the projects root path independent of the calling function?
Or is my code design wrong? Should I pass the file path into the function?

Solution

Pass in the filepath as a parameter to the function (as indicated in your last question).

More details:

The relative path "wordlists/specialChars.txt" is in fact not dependent on where the source file is located (such as Main.go or CleanupUtil_test.go), but where you execute it from. So you could run your tests from your root directory and then it would actually work. In short, the current working directory is relevant.

Still, I’d recommend specifying the path, because that makes your function more reusable and universal.

Maybe you don’t even need to put this information into a file, but can simply have a string containing those chars. In this case you could also check if https://golang.org/pkg/regexp/#Regexp.ReplaceAll already covers your use case.

Answered By – Peter Goetz

Answer Checked By – Marilyn (GoLangFix Volunteer)

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