diff --git a/src/file/env.rs b/src/file/env.rs
index 83c6006..005ced2 100644
--- a/src/file/env.rs
+++ b/src/file/env.rs
@@ -1,13 +1,26 @@
-use std::fs::File;
+use std::fs::{File, OpenOptions};
+use std::io::Write;
 
 pub struct FileEnv {
     pub open: FileOpen,
+    pub append_line: FileAppendLine,
 }
 impl Default for FileEnv {
     fn default() -> Self {
         Self {
             open: |path| File::open(path),
+            append_line: |file_name, line| {
+                let mut file = OpenOptions::new()
+                    .write(true)
+                    .append(true)
+                    .create(true)
+                    .open(file_name)
+                    .unwrap();
+                writeln!(file, "{}", line)?;
+                Ok(())
+            },
         }
     }
 }
 pub type FileOpen = fn(path: &str) -> std::io::Result<File>;
+pub type FileAppendLine = fn(paht: &str, line: &str) -> std::io::Result<()>;
diff --git a/src/history/add.rs b/src/history/add.rs
index 580c219..90e2628 100644
--- a/src/history/add.rs
+++ b/src/history/add.rs
@@ -1,19 +1,10 @@
+use crate::file::FileEnv;
 use crate::prelude::*;
 
-use std::fs::OpenOptions;
-use std::io::prelude::*;
-
 use super::Link;
 
-pub fn add(link: &Link, file_name: &str) -> Result<()> {
-    let mut file = OpenOptions::new()
-        .write(true)
-        .append(true)
-        .create(true)
-        .open(file_name)
-        .unwrap();
-
-    writeln!(file, "{}", link.href)?;
+pub fn add(link: &Link, file_name: &str, e: &FileEnv) -> Result<()> {
+    (e.append_line)(file_name, &link.href)?;
     Ok(())
 }
 
@@ -43,7 +34,7 @@ mod tests {
             length: None,
         };
         //when
-        add(&link, &file_name)?;
+        add(&link, &file_name, &FileEnv::default())?;
 
         //then
         let content: Vec<String> = read_text_file(&file_name)?;
@@ -72,7 +63,7 @@ mod tests {
             length: None,
         };
         //when
-        add(&link, &file_name)?;
+        add(&link, &file_name, &FileEnv::default())?;
 
         //then
         let content: Vec<String> = read_text_file(&file_name)?;
diff --git a/src/lib.rs b/src/lib.rs
index 57fab72..8f4d03a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -29,7 +29,7 @@ pub fn run(subscriptions: &str, history: &str, site: &str, e: Env) -> Result<()>
                 if !history::find(&link, history, &e.file)? {
                     println!("Downloading {}: {}", &channel_name, entry.title().as_str());
                     (e.fetch.download)(&link)?;
-                    history::add(&link, history)?;
+                    history::add(&link, history, &e.file)?;
                 }
             }
         }