Rollup merge of rust-lang#44313 - RalfJung:book, r=nikomatsakis

rustbook: remove dead test functions

There is no "test" subcommand added to the `clap::App`, so this is all dead code.

Cc @steveklabnik -- your [commit](RalfJung@a076961) introducing this stated the intention of having both commands, but it seems nobody has missed the `test` command since February.

Author: Mark-Simulacrum

src/tools/rustbook/src/main.rs

@@ -41,7 +41,6 @@ fn main() {
     // Check which subcomamnd the user ran...
     let res = match matches.subcommand() {
         ("build", Some(sub_matches)) => build(sub_matches),
-        ("test", Some(sub_matches)) => test(sub_matches),
         (_, _) => unreachable!(),
     };
 
@@ -65,14 +64,6 @@ fn build(args: &ArgMatches) -> Result<(), Box<Error>> {
     Ok(())
 }
 
-fn test(args: &ArgMatches) -> Result<(), Box<Error>> {
-    let mut book = build_mdbook_struct(args);
-
-    try!(book.test());
-
-    Ok(())
-}
-
 fn build_mdbook_struct(args: &ArgMatches) -> mdbook::MDBook {
     let book_dir = get_book_dir(args);
     let mut book = MDBook::new(&book_dir).read_config();