Increase unit test coverage

[saschagrunert]

We should actively work on increasing the unit test coverage by using the mockall framework. This should be done in the same way like we did it for the server init:

conmon-rs/conmon-rs/server/src/init.rs

Lines 11 to 12 in e6084da

	#[cfg(test)]
	use mockall::{automock, predicate::*};

conmon-rs/conmon-rs/server/src/init.rs

Lines 72 to 92 in e6084da

	#[cfg(test)]
	mod tests {
	use super::*;
	use std::{ptr, str};
	use tempfile::tempfile;
	fn new_sut(mock: MockInitImpl) -> Init<MockInitImpl> {
	Init::<MockInitImpl> { imp: mock }
	}
	#[test]
	fn unset_locale() -> Result<()> {
	let mut mock = MockInitImpl::new();
	mock.expect_setlocale()
	.withf(|x, _| *x == LC_ALL)
	.returning(|_, _| ptr::null_mut());
	let sut = new_sut(mock);
	sut.unset_locale()
	}

[swastik959]

@saschagrunert hi I want to work on this issue but getting confused how did you wrote these test cases