Running `devbox run test` with a single-user installation doesn't work

[DerArkeN]

What happened?

When running devbox run test I got the following error for all testscripts:

    --- FAIL: TestScripts/add_outputs.test (1.06s)
        testscript.go:558: # Testscript to add packages with non-default outputs (1.030s)
            # Add prometheus with default outputs. It will not have promtool. (0.026s)
            > exec devbox add prometheus
            [stderr]

            Error: Unable to find nix startup file. If /nix directory exists it's possible the installation did not complete successfully. Follow instructions at https://nixos.org/download.html for manual install.

            [exit status 1]
            FAIL: add/add_outputs.test.txt:6: unexpected command failure

When adding a print to internal/nix/source.go in the func SourceNixEnv() loop I found out that since a go test is in it's own environment the home variable refers to something like: /tmp/TestScriptspath.test632767911/001/
This means the test looks for nix installations in following directories:

            /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
            /tmp/TestScriptspath.test632767911/001/.nix-profile/etc/profile.d/nix.sh
            /tmp/TestScriptspath.test632767911/001/.local/state/nix/profile/etc/profile.d/nix.sh
            /tmp/TestScriptspath.test632767911/001/.local/state/nix/profiles/profile/etc/profile.d/nix.sh

Since I am running a single-user installation I don't have /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh which results in the tests failing.

Running devbox run docker-testscripts results in an endless lines of errors as well.

Steps to reproduce

1. Install devbox and nix with a single-user installation
2. Clone this repository
3. Start a devbox shell
4. Run devbox run test

Command

No response

devbox.json

No response

Devbox version

0.13.3

Nix version

No response

What system does this bug occur on?

Linux (x86-64)

Debug logs

No response