Better test and document the dir segment

src/modules/directory.rs

@@ -61,6 +61,9 @@ fn get_repo_root(repo: &Repository) -> &Path {
 }
 
 /// Contract the root component of a path
+/// 
+/// Replaces the `top_level_path` in a given `full_path` with the provided
+/// `top_level_replacement`.
 fn contract_path(full_path: &Path, top_level_path: &Path, top_level_replacement: &str) -> String {
     if !full_path.starts_with(top_level_path) {
         return full_path.to_str().unwrap().to_string();
@@ -83,6 +86,9 @@ fn contract_path(full_path: &Path, top_level_path: &Path, top_level_replacement:
 }
 
 /// Truncate a path to only have a set number of path components
+/// 
+/// Will truncate a path to only show the last `length` components in a path.
+/// If a length of `0` is provided, the path will not be truncated.
 fn truncate(dir_string: String, length: usize) -> String {
     if length == 0 {
         return dir_string;
@@ -143,6 +149,24 @@ mod tests {
     //     assert_eq!(segment.output(), "/var");
     // }
 
+    #[test]
+    fn contract_home_directory() {
+        let full_path = Path::new("/Users/astronaut/schematics/rocket");
+        let home = Path::new("/Users/astronaut");
+
+        let output = contract_path(full_path, home, "~");
+        assert_eq!(output, "~/schematics/rocket");
+    }
+
+    #[test]
+    fn contract_repo_directory() {
+        let full_path = Path::new("/Users/astronaut/dev/rocket-controls/src");
+        let repo_root = Path::new("/Users/astronaut/dev/rocket-controls");
+
+        let output = contract_path(full_path, repo_root, "rocket-controls");
+        assert_eq!(output, "rocket-controls/src");
+    }
+
     #[test]
     fn truncate_smaller_path_than_provided_length() {
         let path = "~/starship";
@@ -158,7 +182,7 @@ mod tests {
     }
 
     #[test]
-    fn truncate_slightly_larger_path_then_provided_length() {
+    fn truncate_slightly_larger_path_than_provided_length() {
         let path = "~/starship/engines/booster";
         let output = truncate(path.to_string(), 3);
         assert_eq!(output, "starship/engines/booster")