Ensure dash appears in USAGE for short form alias

Although specifying single letter aliases without a dash works, it
generated incorrect USAGE documentation (the dash is missing).

This moves the alias normalization to happen earlier, which ensures the
aliases are described correctly in the USAGE documentation.

Author: sambostock

lib/thor/parser/option.rb

@@ -11,7 +11,7 @@ def initialize(name, options = {})
       super
       @lazy_default   = options[:lazy_default]
       @group          = options[:group].to_s.capitalize if options[:group]
-      @aliases        = Array(options[:aliases])
+      @aliases        = normalize_aliases(options[:aliases])
       @hide           = options[:hide]
     end
 
@@ -155,5 +155,11 @@ def undasherize(str)
     def dasherize(str)
       (str.length > 1 ? "--" : "-") + str.tr("_", "-")
     end
+
+    private
+
+    def normalize_aliases(aliases)
+      Array(aliases).map { |short| short.to_s.sub(/^(?!\-)/, "-") }
+    end
   end
 end

lib/thor/parser/options.rb

@@ -50,8 +50,7 @@ def initialize(hash_options = {}, defaults = {}, stop_on_unknown = false, disabl
       options.each do |option|
         @switches[option.switch_name] = option
 
-        option.aliases.each do |short|
-          name = short.to_s.sub(/^(?!\-)/, "-")
+        option.aliases.each do |name|
           @shorts[name] ||= option.switch_name
         end
       end

spec/parser/option_spec.rb

@@ -108,8 +108,8 @@ def option(name, options = {})
         expect(parse([:foo, :b, "--bar"], true).name).to eq("foo")
       end
 
-      it "sets all other items as aliases" do
-        expect(parse([:foo, :b, "--bar"], true).aliases).to eq([:b, "--bar"])
+      it "sets all other items as normalized aliases" do
+        expect(parse([:foo, :b, "--bar"], true).aliases).to eq(["-b", "--bar"])
       end
     end
   end
@@ -259,6 +259,10 @@ def option(name, options = {})
       it "does not negate the aliases" do
         expect(parse([:foo, "-f", "-b"], :boolean).usage).to eq("-f, -b, [--foo], [--no-foo]")
       end
+
+      it "normalizes the aliases" do
+        expect(parse([:foo, :f, "-b"], :required).usage).to eq("-f, -b, --foo=FOO")
+      end
     end
   end
 end