Relative paths work under normal execution but cause IO exception when debugging in C#

Within a project folder I have a subfolder docs, which contains a number of documents such as .json files that are used within my application.

I want to be able to access these files during both normal execution and when debugging, especially when I need to debug tests.

At the moment I have the following line that reads in data from a specific file:

string data = System.IO.File.ReadAllText("./Docs/file.json");

This works normally, but when I debug my application I get the following exception

System.IO.DirectoryNotFoundException: 'Could not find a part of the path 
'C:\Project\Project.Test\bin\Debug\net
coreapp2.1\Docs\file.json'.'

I assume this is because when the debugger is ran it is executing from a different location to normal, and therefore the relative path used above is different and thus the file can't be found.

To try and rectify this I used Directory.GetCurrentDirectory(), as below:

data = System.IO.File.ReadAllText(Directory.GetCurrentDirectory() + @"\Docs\file.json");

But this produced exactly the same exception, what do I need to change so that I can use the relative path of my project and find the file I need under every circumstance?