diff --git a/src/options/config.rs b/src/options/config.rs
index fc4f301..91fa4a6 100644
--- a/src/options/config.rs
+++ b/src/options/config.rs
@@ -6,6 +6,8 @@ use std::process::Command;
 use std::sync::Arc;
 use std::{env, fs};
 use tokio::time::Duration;
+use std::fs::OpenOptions;
+use std::io::{self, Write};
 
 const CONFIG_PATH: &str = "settings.json";
 
@@ -249,9 +251,27 @@ fn config_comparing(local: &Processes, remote: &Processes) -> ConfigActuality {
 
 fn save_new_config(config: &Processes, config_file: &str) -> Result<(), CustomError> {
     match serde_json::to_string_pretty(&config) {
-        Ok(st) => match fs::write(config_file, st) {
-            Ok(_) => Ok(()),
-            Err(_) => Err(CustomError::Fatal),
+        // Ok(st) => match fs::write(config_file, st) {
+        //     Ok(_) => Ok(()),
+        //     Err(_) => Err(CustomError::Fatal),
+        // },
+        Ok(st) => {
+            let file = OpenOptions::new()
+                .read(true)
+                .write(true)        
+                .create(true)       
+                .truncate(false)    
+                .open(config_file); 
+            match file {
+                Ok(fs) => {
+                    let mut writer = fs;
+                    match writeln!(writer, "{}", st) {
+                        Ok(_) => Ok(()),
+                        Err(_) => Err(CustomError::Fatal), 
+                    }
+                },
+                Err(_) => return Err(CustomError::Fatal)
+            }
         },
         Err(_) => Err(CustomError::Fatal),
     }
@@ -263,3 +283,60 @@ fn parse_extern_config(json_string: &str) -> Option<Processes> {
     }
     None
 }
+
+
+
+
+// unit tests
+#[cfg(test)]
+ mod config_unittests {
+    use super::*;
+    #[test]
+    fn parsing_valid_conf() {
+        assert!(load_processes("tests/examples/settings.json").is_some());
+    }
+    #[test]
+    fn parsing_invalid_conf() {
+        assert!(load_processes("tests/examples/invalid_config.json").is_none());
+    }
+    #[test]
+    fn configuration_comparing() {
+        // old one (kinda local)
+        let a = Processes {
+            date_of_creation: String::from("1"),
+            config_server: String::new(),
+            processes: vec![],
+        };
+        // new one (kinda remote)
+        let b = Processes {
+            date_of_creation: String::from("2"),
+            config_server: String::new(),
+            processes: vec![],
+        };
+
+        assert_eq!(config_comparing(&a, &b), ConfigActuality::Remote);
+    }
+    #[test]
+    fn get_actual_config_mechanism() {
+        assert!(get_actual_config().is_some())
+    }
+    #[test]
+    fn save_config() {
+        let a = Processes {
+            date_of_creation: String::from("1"),
+            config_server: String::new(),
+            processes: vec![],
+        };
+        assert!(save_new_config(&a, "tests/examples/save-conf.json").is_ok());
+    }
+
+    #[test]
+    fn save_to_zero_file() {
+        let a = Processes {
+            date_of_creation: String::from("1"),
+            config_server: String::new(),
+            processes: vec![],
+        };
+        assert!(save_new_config(&a, "tests/examples/none.json").is_ok());
+    }
+ }
\ No newline at end of file
diff --git a/src/options/structs.rs b/src/options/structs.rs
index 6838703..7e56077 100644
--- a/src/options/structs.rs
+++ b/src/options/structs.rs
@@ -3,7 +3,9 @@ use serde::{Deserialize, Serialize};
 /// # an Error enum (next will be deleted and replaced)
 pub enum CustomError {
     Fatal,
+
 }
+#[derive(Debug, PartialEq)]
 pub enum ConfigActuality {
     Local,
     Remote,
diff --git a/tests/examples/invalid_config.json b/tests/examples/invalid_config.json
new file mode 100644
index 0000000..3a2228e
--- /dev/null
+++ b/tests/examples/invalid_config.json
@@ -0,0 +1,33 @@
+{
+    "configServer" : "localhost",
+    "processes": [
+      {
+        "name": "temp-process",
+        "path": "/home/user/monitor/runner-rs/temp-process",
+        "dependencies": {
+          "files": [
+            {
+              "filename": "dep-file",
+              "src": "/home/user/monitor/runner-rs/tests/examples/",
+              "triggers": {
+                "onDelete": "stop",
+                "onChange": "stay"
+              }
+            }
+          ],
+          "services": [
+            {
+              "hostname": "ya.ru",
+              "port": 443,
+              "triggers": {
+                "wait": 10,
+                "delay": 2,
+                "onLost": "hold"
+              }
+            }
+          ]
+        }
+      }
+    ]
+  }
+  
\ No newline at end of file
diff --git a/tests/examples/none.json b/tests/examples/none.json
new file mode 100644
index 0000000..e6c4897
--- /dev/null
+++ b/tests/examples/none.json
@@ -0,0 +1,5 @@
+{
+  "dateOfCreation": "1",
+  "configServer": "",
+  "processes": []
+}
diff --git a/tests/examples/save-conf.json b/tests/examples/save-conf.json
new file mode 100644
index 0000000..e6c4897
--- /dev/null
+++ b/tests/examples/save-conf.json
@@ -0,0 +1,5 @@
+{
+  "dateOfCreation": "1",
+  "configServer": "",
+  "processes": []
+}