Added copy function, test, and docs. (#5)

* Added copy function, test, and docs.

cmd/implants/eldritch/src/file/copy_impl.rs

@@ -1,5 +1,42 @@
 use anyhow::Result;
+use std::fs;
 
-pub fn copy(_src: String, _dst: String) -> Result<()> {
-    unimplemented!("Method unimplemented")
-}
+pub fn copy(src: String, dst: String) -> Result<()> {
+    fs::copy(src, dst)?;
+    Ok(())
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::fs::File;
+    use std::io::prelude::*;
+    use std::fs::remove_file;
+
+    #[test]
+    fn test_copy() -> anyhow::Result<()>{
+        let _ = remove_file(String::from("/tmp/win_copy1"));
+        let _ = remove_file(String::from("/tmp/win_copy2"));
+
+        // Create file
+        let mut file = File::create("/tmp/win_copy1")?;
+        // Write to file
+        file.write_all(b"Hello, world!")?;
+
+        // Run our code
+        copy(String::from("/tmp/win_copy1"), String::from("/tmp/win_copy2"))?;
+
+        // Open copied file
+        let mut winfile = File::open("/tmp/win_copy2")?;
+        // Read
+        let mut contents = String::new();
+        winfile.read_to_string(&mut contents)?;
+        // Compare
+        assert_eq!(contents, "Hello, world!");
+
+        remove_file(String::from("/tmp/win_copy1"))?;
+        remove_file(String::from("/tmp/win_copy2"))?;
+        Ok(())
+    }
+}

docs/_data/eldritch_nav.yml

@@ -16,7 +16,7 @@
         - name: "file.copy"
           signature: "file.copy(src: str, dst: str) -> None"
           link: stdlib_file_copy
-          content: The <b>file.copy</b> method is very cool, and will be even cooler when Nick documents it.
+          content: The <b>file.copy</b> copies a file from src path to dst path. If dst path doesn't exist it will be created.
         - name: "file.download"
           signature: "file.download(uri: str, dst: str) -> None"
           link: stdlib_file_download