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.

2 files changed, 17 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);
 }
diff --git a/src/tests.rs b/src/tests.rs
new file mode 100644
index 0000000..20bbcc5
--- /dev/null
+++ b/src/tests.rs
@@ -0,0 +1,14 @@
+use super::build_alias;
+
+#[test]
+fn test_build_alias() {
+    assert_eq!(
+        "alias farnsworth-hubert Hubert Farnsworth <professor@planetexpress.com>",
+        build_alias("From: Hubert Farnsworth <professor@planetexpress.com>")
+    );
+
+    assert_eq!(
+        "alias lab-harvard Harvard Innovation Lab <noreply@eventbrite.com>",
+        build_alias("From: Harvard Innovation Lab <noreply@eventbrite.com>")
+    );
+}