Add a function to load a config from file.

src/config/full.rs

@@ -1,3 +1,4 @@
+use std::path::Path;
 use std::path::PathBuf;
 use tokio::fs::File;
 use tokio::io::AsyncWriteExt;
@@ -18,6 +19,23 @@ impl Config {
         })
     }
 
+    pub(crate) async fn load_from_file<P: AsRef<Path>>(
+        path: P,
+    ) -> Result<Config, Box<dyn std::error::Error>> {
+        async fn inner(path: &Path) -> Result<Config, Box<dyn std::error::Error>> {
+            let contents = tokio::fs::read_to_string(path).await?;
+            let parsed_contents: RawConfig = toml::from_str(contents.as_str())?;
+            let root_directory = path
+                .parent()
+                .expect("Writer config must exist inside a directory.");
+            Ok(Config {
+                raw: parsed_contents,
+                root_dir: root_directory.to_owned(),
+            })
+        }
+        inner(path.as_ref()).await
+    }
+
     pub(crate) async fn write_to_disk(&self) -> Result<(), Box<dyn std::error::Error>> {
         let mut config_file = File::create(self.get_path_to_config_file()).await?;
         config_file