Add thorough tests for all shell behavior (both interactive and non-interactive/scripts)

[certik]

Right now a lot of the behavior is not tested, but as things get more complex we need to ensure that we didn't break anything. So we need thorough tests.

[certik]

@prsabahrami How can we test snippets of shell scripts, say:

A = "1.2.3"
echo $A

And ensure it actually prints correctly on all platforms? Currently this one works on linux, but not windows (#127). If we can do this, then we can simply add scripts for any new feature and ensure they just work on all platforms. The testing of printing might be tricky, so an alternative is to at least ensure they run, and we can add test using "if" statements there.

[prsabahrami]

@prsabahrami How can we test snippets of shell scripts, say:

A = "1.2.3"
echo $A

And ensure it actually prints correctly on all platforms? Currently this one works on linux, but not windows (#127). If we can do this, then we can simply add scripts for any new feature and ensure they just work on all platforms. The testing of printing might be tricky, so an alternative is to at least ensure they run, and we can add test using "if" statements there.

@certik IINW we can use pixi to set various environments for testing.