tests(add): introduce basics tests for add

tests/common/client.rs

@@ -1,4 +1,5 @@
 use nextsync::config::config::Config;
+use std::fs::OpenOptions;
 use rand::{distributions::Alphanumeric, Rng};
 use std::env;
 use std::fs::{self, File};
@@ -125,6 +126,18 @@ impl ClientTest {
         Ok(())
     }
 
+    pub fn add_ignore_rule(&self, rule: &str) {
+        let mut nsignore_path = self.volume.clone();
+        nsignore_path.push_str("/.nsignore");
+    let mut file = OpenOptions::new()
+        .write(true)
+        .create(true)
+        .append(true)
+        .open(nsignore_path).unwrap();
+
+        let _ = writeln!(file, "{rule}").unwrap();
+    }
+
     // pub fn has_file(&mut self, file: &str, content: &str) -> bool {
     //     let full_path = PathBuf::from(self.volume.clone()).join(file);