Refactor test framework code.

src/tests/mod.rs

@@ -92,16 +92,14 @@ fn extract_output(code: impl Into<String>) -> String {
 pub fn script_test(input: &str, target: TestOutcomeTarget) {
     let code = fs::read_to_string(input)
         .unwrap_or_else(|_| panic!("Failed to open {input} test file"));
-
     // Extract output from script comment.
     let mut output = extract_output(&code);
-
     // If output is not in comment, try to read from .output.txt file.
     if output.is_empty() {
-        let output_path = PathBuf::from(input.replace(".ab", ".output.txt"));
-        output = if output_path.exists() {
-            fs::read_to_string(output_path)
-                .unwrap_or_else(|_| panic!("Failed to open {input}.output.txt file"))
+        let path = PathBuf::from(input.replace(".ab", ".output.txt"));
+        output = if path.exists() {
+            fs::read_to_string(&path)
+                .unwrap_or_else(|_| panic!("Failed to open {} test file", path.display()))
         } else {
             SUCCEEDED.to_string()
         };