add error handling to fs resolver

zokrates_fs_resolver/src/lib.rs

@@ -4,17 +4,82 @@ use std::fs::File;
 use std::io;
 
 pub fn resolve(location: &Option<String>, source: &String) -> Result<(BufReader<File>, String, String), io::Error> {
-	let path = match location {
-		Some(location) => {
-			PathBuf::from(location).join(PathBuf::from(source))
-		},
-		None => {
-			PathBuf::from(source)
-		}
-	};
+	// the fs resolver has to be provided a location, as it supports relative paths
+	match location {
+		Some(location) => resolve_with_location(location, source),
+		None => Err(io::Error::new(io::ErrorKind::Other, "No location provided"))
+	}
+}
 
-	let next_location = path.parent().unwrap().to_path_buf().into_os_string().into_string().unwrap();
-	let alias = path.file_stem().unwrap().to_os_string().to_string_lossy().to_string();
+fn resolve_with_location(location: &String, source: &String) -> Result<(BufReader<File>, String, String), io::Error> {
+	let path = 	PathBuf::from(location).join(PathBuf::from(source));
+	let (next_location, alias) = generate_next_parameters(&path)?;
 
 	File::open(path).and_then(|f| Ok((BufReader::new(f), next_location, alias)))
+}
+
+fn generate_next_parameters(path: &PathBuf) -> Result<(String, String), io::Error> {
+	match (path.parent(), path.file_stem()) {
+		(Some(parent), Some(stem)) => Ok(
+			(
+				parent.to_path_buf().into_os_string().into_string().unwrap(),
+				stem.to_os_string().to_string_lossy().to_string()
+			)
+		),
+		_ => Err(io::Error::new(io::ErrorKind::Other, "Invalid path"))
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn valid_path_with_location() {
+		let (_, next_location, alias) = resolve(&Some(String::from("./src")), &String::from("lib.rs")).unwrap();
+		assert_eq!(next_location, String::from("./src"));
+		assert_eq!(alias, String::from("lib"));
+	}
+
+	#[test]
+	fn valid_path_without_location() {
+		let res = resolve(&None, &String::from("./src/lib.rs"));
+		assert!(res.is_err());
+	}
+
+	#[test]
+	fn non_existing_file() {
+		let res = resolve(&Some(String::from("./src")), &String::from("rubbish.rs"));
+		assert!(res.is_err());
+	}
+
+	#[test]
+	fn invalid_location() {
+		let res = resolve(&Some(String::from(",8!-$2abc")), &String::from("foo.code"));
+		assert!(res.is_err());
+	}
+
+	#[test]
+	fn invalid_file() {
+		let res = resolve(&Some(String::from("./src")), &String::from(",8!-$2abc"));
+		assert!(res.is_err());
+	}
+
+	#[test]
+	fn not_a_file() {
+		let res = resolve(&Some(String::from(".")), &String::from("/src/"));
+		assert!(res.is_err());
+	}
+
+	#[test]
+	fn no_parent() {
+		let res = resolve(&Some(String::from(".")), &String::from("."));
+		assert!(res.is_err());
+	}
+
+	#[test]
+	fn no_file_name() {
+		let res = resolve(&Some(String::from(".")), &String::from(""));
+		assert!(res.is_err());
+	}
 }