Simplify split_args code, add a unit test for it and run it into CI

.github/workflows/ci.yml

@@ -131,3 +131,12 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - run: python tools/check_intrinsics_duplicates.py
+
+  build_system:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Test build system
+        run: |
+          cd build_system
+          cargo test

build_system/src/utils.rs

@@ -306,7 +306,6 @@ pub fn split_args(args: &str) -> Result<Vec<String>, String> {
     let args = args.trim();
     let mut iter = args.char_indices().peekable();
 
-    while iter.peek().is_some() {
     while let Some((pos, c)) = iter.next() {
         if c == ' ' {
             out.push(args[start..pos].to_string());
@@ -347,7 +346,6 @@ pub fn split_args(args: &str) -> Result<Vec<String>, String> {
             iter.next();
         }
     }
-    }
     let s = args[start..].trim();
     if !s.is_empty() {
         out.push(s.to_string());
@@ -364,3 +362,26 @@ pub fn remove_file<P: AsRef<Path>>(file_path: &P) -> Result<(), String> {
         )
     })
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_split_args() {
+        // Missing `"` at the end.
+        assert!(split_args("\"tada").is_err());
+        // Missing `'` at the end.
+        assert!(split_args("\'tada").is_err());
+
+        assert_eq!(
+            split_args("a \"b\" c"),
+            Ok(vec!["a".to_string(), "\"b\"".to_string(), "c".to_string()])
+        );
+        // Trailing whitespace characters.
+        assert_eq!(
+            split_args("    a    \"b\" c    "),
+            Ok(vec!["a".to_string(), "\"b\"".to_string(), "c".to_string()])
+        );
+    }
+}