improve error management with thiserror use

- add thiserror dependency
- use distinct Error enum in lib and server

src/server.rs

@@ -1,9 +1,39 @@
 use crate::server::utils::{get_free_port, wait_for_port};
 use mktemp::Temp;
-use std::error::Error;
-use std::io::{Cursor, Read};
+use std::io::{self, Cursor, Read};
 use std::process::{Child, Stdio};
-use zip::ZipArchive;
+use thiserror::Error;
+use zip::{result::ZipError, ZipArchive};
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error("Grammalecte-server failed to launch process")]
+    StartServerProcess(#[source] io::Error),
+
+    #[error("Get an available port failed")]
+    GetFreePort(#[source] io::Error),
+
+    #[error("Port {port} did not open in time!")]
+    WaitPortOpen { port: u16 },
+
+    #[error("Create temporary directory failed")]
+    CreateTempDir(#[source] io::Error),
+
+    #[error("Zip archive loading failed")]
+    ZipArchiveLoading(#[source] ZipError),
+
+    #[error("Access file by index failed")]
+    ZipFileIndex(#[source] ZipError),
+
+    #[error("Create directory for files from zip")]
+    CreateDirectoryForZipFile(#[source] io::Error),
+
+    #[error("Read file from zip archive")]
+    ZipFileReadToEnd(#[source] io::Error),
+
+    #[error("Write file from archive on disk")]
+    WriteFile(#[source] io::Error),
+}
 
 pub struct EmbeddedServer {
     _srv_dir: Temp,
@@ -13,29 +43,31 @@ pub struct EmbeddedServer {
 
 impl EmbeddedServer {
     /// Start embedded Grammalecte server on a random free port
-    pub fn start() -> Result<Self, Box<dyn Error>> {
-        Self::start_listen_on_port(get_free_port()?)
+    pub fn start() -> Result<Self, Error> {
+        Self::start_listen_on_port(get_free_port())
     }
 
     /// Start embedded Grammalecte server on a given port
-    pub fn start_listen_on_port(port: u16) -> Result<Self, Box<dyn Error>> {
+    pub fn start_listen_on_port(port: u16) -> Result<Self, Error> {
         log::info!("Will start server");
         // First, unpack server
-        let dest = mktemp::Temp::new_dir()?;
+        let dest = mktemp::Temp::new_dir().map_err(Error::CreateTempDir)?;
         let cursor = Cursor::new(include_bytes!("GrammalecteDist.zip"));
-        let mut zip = ZipArchive::new(cursor)?;
+        let mut zip = ZipArchive::new(cursor).map_err(Error::ZipArchiveLoading)?;
         for i in 0..zip.len() {
-            let mut file = zip.by_index(i)?;
+            let mut file = zip.by_index(i).map_err(Error::ZipFileIndex)?;
             if file.is_dir() {
                 log::debug!("Create directory: {}", file.name());
-                std::fs::create_dir_all(dest.join(file.name()))?;
+                std::fs::create_dir_all(dest.join(file.name()))
+                    .map_err(Error::CreateDirectoryForZipFile)?;
             } else {
                 log::debug!("Decompress file: {}", file.name());
 
                 let mut buff = Vec::with_capacity(file.size() as usize);
-                file.read_to_end(&mut buff)?;
+                file.read_to_end(&mut buff)
+                    .map_err(Error::ZipFileReadToEnd)?;
 
-                std::fs::write(dest.join(file.name()), buff)?;
+                std::fs::write(dest.join(file.name()), buff).map_err(Error::WriteFile)?;
             }
         }
 
@@ -54,7 +86,8 @@ impl EmbeddedServer {
             .arg(port.to_string())
             .stdout(Stdio::null())
             .stderr(Stdio::null())
-            .spawn()?;
+            .spawn()
+            .map_err(Error::StartServerProcess)?;
 
         wait_for_port(port)?;
 
@@ -78,11 +111,12 @@ impl Drop for EmbeddedServer {
 }
 
 mod utils {
-    use std::io::ErrorKind;
     use std::time::Duration;
 
+    use super::Error;
+
     /// Get a free port
-    pub fn get_free_port() -> std::io::Result<u16> {
+    pub fn get_free_port() -> u16 {
         let mut port = 0;
 
         while !(2000..=64000).contains(&port) {
@@ -93,10 +127,10 @@ mod utils {
             port += 1;
         }
 
-        Ok(port)
+        port
     }
 
-    pub fn wait_for_port(port: u16) -> std::io::Result<()> {
+    pub fn wait_for_port(port: u16) -> Result<(), Error> {
         for _ in 0..50 {
             if port_scanner::scan_port(port) {
                 return Ok(());
@@ -104,9 +138,6 @@ mod utils {
             std::thread::sleep(Duration::from_millis(100));
         }
 
-        Err(std::io::Error::new(
-            ErrorKind::Other,
-            format!("Port {} did not open in time!", port),
-        ))?
+        Err(Error::WaitPortOpen { port })
     }
 }