Teach publish the --dry-run flag

Closes rust-lang#1332

src/bin/publish.rs

@@ -9,6 +9,7 @@ struct Options {
     flag_manifest_path: Option<String>,
     flag_verbose: bool,
     flag_no_verify: bool,
+    flag_dry_run: bool,
 }
 
 pub const USAGE: &'static str = "
@@ -23,6 +24,7 @@ Options:
     --token TOKEN           Token to use when uploading
     --no-verify             Don't verify package tarball before publish
     --manifest-path PATH    Path to the manifest to compile
+    --dry-run               Performs all checks without uploading
     -v, --verbose           Use verbose output
 
 ";
@@ -34,11 +36,13 @@ pub fn execute(options: Options, config: &Config) -> CliResult<Option<()>> {
         flag_host: host,
         flag_manifest_path,
         flag_no_verify: no_verify,
+        flag_dry_run: dry,
         ..
     } = options;
 
     let root = try!(find_root_manifest_for_cwd(flag_manifest_path.clone()));
-    ops::publish(&root, config, token, host, !no_verify).map(|_| None).map_err(|err| {
+    ops::publish(&root, config, token, host,
+                 !no_verify, dry).map(|_| None).map_err(|err| {
         CliError::from_boxed(err, 101)
     })
 }

src/cargo/ops/registry.rs

@@ -30,7 +30,13 @@ pub fn publish(manifest_path: &Path,
                config: &Config,
                token: Option<String>,
                index: Option<String>,
-               verify: bool) -> CargoResult<()> {
+               verify: bool,
+               dry: bool) -> CargoResult<()> {
+    if !verify && dry {
+        return Err(human("cannot specify both no verify and dry run \
+                          simultaneously"))
+    }
+
     let mut src = try!(PathSource::for_path(manifest_path.parent().unwrap(),
                                             config));
     try!(src.update());
@@ -45,8 +51,13 @@ pub fn publish(manifest_path: &Path,
                                     false, true)).unwrap();
 
     // Upload said tarball to the specified destination
+    // However, do not upload if performing a dry run
     try!(config.shell().status("Uploading", pkg.package_id().to_string()));
-    try!(transmit(&pkg, &tarball, &mut registry));
+    if !dry {
+        try!(transmit(&pkg, &tarball, &mut registry));
+    } else {
+        try!(config.shell().warn("Aborting upload due to dry run"));
+    }
 
     Ok(())
 }