Construct book build path outside process_book

src/cmd/shelf.rs

@@ -1,4 +1,3 @@
-use std::env::current_dir;
 use std::fs::File;
 use std::io::Read;
 use std::io::Write;
@@ -69,18 +68,16 @@ fn update_index(
     Ok(())
 }
 
-fn process_book(path: &str, shelf_url: &PathBuf) -> Result<BookContext> {
+fn process_book(path: &str, books_dir: &PathBuf, shelf_url: &PathBuf) -> Result<BookContext> {
     let book_dir = path.try_resolve()?;
     let book_dir = std::fs::canonicalize(book_dir)?;
     let mut book = MDBook::load(book_dir)?;
 
     // Build book
     let title = book.config.book.title.clone().unwrap();
-    let mut path = current_dir()?;
-    path.push(BOOKSHELF_DIR);
-    path.push(BOOKS_DIR);
-    path.push(title);
-    book.config.build.build_dir = path;
+    let mut build_path = books_dir.to_owned();
+    build_path.push(title);
+    book.config.build.build_dir = build_path;
     // Create back reference to bookshelf
     book.config.book.shelf_url = Some(shelf_url.to_owned());
     book.build()?;
@@ -131,6 +128,10 @@ pub fn execute(_args: &ArgMatches) -> Result<()> {
     writeln!(summary_file, "# Summary")?;
     writeln!(summary_file, "- [Index](./{INDEX_MD_FILE})")?;
 
+    let mut books_build_dir = std::env::current_dir()?;
+    books_build_dir.push(BOOKSHELF_DIR);
+    books_build_dir.push(BOOKS_DIR);
+
     for sb in &shelf_config.books {
         let book_path = if let Some(url) = &sb.git_url {
             prepare_git(sb, url)
@@ -142,7 +143,7 @@ pub fn execute(_args: &ArgMatches) -> Result<()> {
         };
 
         if let Some(path) = book_path {
-            let update_context = process_book(&path, &shelf_url)?;
+            let update_context = process_book(&path, &books_build_dir, &shelf_url)?;
             let _ = update_index(
                 &mut index_file,
                 &mut summary_file,