feat: added saving existing file or new file

src/file.rs

@@ -0,0 +1,55 @@
+use std::{
+    fs::{read_to_string, write},
+    path::PathBuf,
+};
+
+pub fn save_file_to_disk(path: PathBuf, text: String) {
+    let save_result = write(path, text);
+
+    match save_result {
+        Ok(_) => println!("Save file successfully"),
+        Err(err) => eprintln!("Error: {}", err),
+    }
+}
+
+pub fn load_file_from_disk(path: PathBuf) -> String {
+    let read_result = read_to_string(path);
+
+    match read_result {
+        Ok(contents) => contents,
+        Err(_) => String::new(),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::fs::{self, remove_file};
+
+    #[test]
+    fn test_save_file_to_disk() {
+        let test_path = PathBuf::from("test_file.txt");
+        let test_content = String::from("Hello, Chat!");
+
+        save_file_to_disk(test_path.clone(), test_content.clone());
+
+        let saved_content = fs::read_to_string(&test_path).unwrap();
+
+        assert_eq!(saved_content, test_content);
+
+        let _ = remove_file(test_path);
+    }
+
+    #[test]
+    fn test_load_file_from_disk() {
+        let test_path = PathBuf::from("test_file.txt");
+        let test_content = String::from("Hello, Chat!");
+        let _ = fs::write(test_path.clone(), test_content.clone());
+
+        let saved_content = load_file_from_disk(test_path.clone());
+
+        assert_eq!(saved_content, test_content);
+
+        let _ = remove_file(test_path);
+    }
+}