import: Exit with a clearer error when wrong args are passed

The help output goes on stdout and so it is lost if being run from
main.py. We need to have something on stderr to make sure that it gets
seen by the user, otherwise there's no clue why the extension subprocess
failed.

3 files changed, 5 insertions, 3 deletions

diff --git a/import/importer_base.rb b/import/importer_base.rb
index 820d53c1..4f3d2f51 100644
--- a/import/importer_base.rb
+++ b/import/importer_base.rb
@@ -34,7 +34,7 @@ module Importer
       opts.on('-?', '--help', 'print this help') do
         puts opts
         print "\n", description
-        exit 1
+        exit 255
       end
     end
 
diff --git a/import/omnibus.to_lorry b/import/omnibus.to_lorry
index df579b9f..ed2e552d 100755
--- a/import/omnibus.to_lorry
+++ b/import/omnibus.to_lorry
@@ -44,8 +44,9 @@ class OmnibusLorryGenerator < Importer::Base
     parsed_arguments = opts.parse!(arguments)
 
     if parsed_arguments.length != 2
+      STDERR.puts "Expected 2 arguments, got #{parsed_arguments}."
       opts.parse(['-?'])
-      exit 1
+      exit 255
     end
 
     definitions_and_project, software_name = parsed_arguments
diff --git a/import/rubygems.to_chunk b/import/rubygems.to_chunk
index c90cda23..0a939a0f 100755
--- a/import/rubygems.to_chunk
+++ b/import/rubygems.to_chunk
@@ -56,8 +56,9 @@ class RubyGemChunkMorphologyGenerator < Importer::Base
     parsed_arguments = opts.parse!(arguments)
 
     if parsed_arguments.length != 2 && parsed_arguments.length != 3
+      STDERR.puts "Expected 2 or 3 arguments, got #{parsed_arguments}."
       opts.parse(['-?'])
-      exit 1
+      exit 255
     end
 
     source_dir, gem_name, expected_version = parsed_arguments