Improve testing

[andreineculau]

I don't know the details, but I have just ran the tests locally bats tests
only to find out that ~/.gitconfig and ~/.gitattributes_global are modified.

[jmurty]

Hi @andreineculau I have fixed one potential place where global Git configs could be set by running bats tests/ in commit f88979c.

I'm not sure how your ~/.gitattributes_global file is being modified, the tests should all write directly to a .gitattributes files in the local temporary test directory as set by bats in the envvar $BATS_TEST_DIRNAME.

[andreineculau]

Nice! 🦸

I didn't have time to check, but I have ~/.gitattributes_global set via git config --global core.attributesfile ~/.gitattributes_global and as it happens it's a symlink. Tests were failing because text-replace didn't work on symlinks.