Add a couple tests for `build_alias`

Create a new `tests` module. This lives in its own file. Not sure if
this is idiomatic Rust, but I prefer the idea of my tests living in a
different file from my code. This module gets included in `main.rs`.

We `use` `build_alias` directly because it's currently a private
function, so doing `use super::*` didn't import it. Not sure if I should
be making it a public function in order to mitigate this.

Add a couple of variant test cases to check the string transformation
that this function should be doing.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/main.rs b/src/main.rs
index 3e4a343..92ea8e1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,8 @@
 use std::io::{self, BufRead};
 
+#[cfg(test)]
+mod tests;
+
 fn handle_alias(s: &str) {
     let alias = build_alias(s);
 }