No way to unset environment variables

[rossmacarthur]

Describe the problem you are trying to solve

I would like to unset environment variables when tests are run.

I need this because I have tests for a CLI program (it uses structopt) and if the environment I'm running in has certain environment variables set it can interfere with the tests.

Describe the solution you'd like

I first tried to remove the environment variables in a build script using std::env::remove_var("VAR") but that didn't work.

Then tried to do this in a build script using cargo:rustc-env=VAR= however this still sets it to an empty string. So a similar option like cargo:rustc-remove-env=VAR would be nice. Of course a way to run some code before tests are run could also solve this.

So now I have to remove the environment variables in every test :/

[lukaslueg]

FWIW there has been discussion about this in #4505 and #4557, specifically this

[ehuss]

I'm going to close in favor of #4505 since it mostly the same thing.

I would recommend writing something in your tests that spawns your CLI with the environment you desire. Cargo's own test suite does this (here).