Disallow invalid tab widths for -w

Previously RDoc::Options used OptionParser::DecimalInteger instead of
Integer for restricting values for the tab width.  Unfortunately the
validator in RDoc uses #to_i to validate the input instead of
Kernel#Integer.  This means no exception is raised for invalid input
such as "-w=3".

Now Integer is used which has the strict validation but also allows
octal, hexadecimal and binary numbers.

Bug reported by Charles Hixson.

History.rdoc

@@ -70,6 +70,8 @@
   * Fixed lexing of escaped characters in strings which could cause
     duplication of the final characters in source code view.  Bug #252 by Mike
     Stok.
+  * Disallow invalid tab widths for -w option.  Bug reported by Charles
+    Hixson.
 
 === 4.0.1 / 2013-03-27
 

lib/rdoc/options.rb

@@ -724,8 +724,10 @@ def parse argv
 
       opt.separator nil
 
-      opt.on("--tab-width=WIDTH", "-w", OptionParser::DecimalInteger,
+      opt.on("--tab-width=WIDTH", "-w", Integer,
              "Set the width of tab characters.") do |value|
+        raise OptionParser::InvalidArgument,
+              "#{value} is an invalid tab width" if value <= 0
         @tab_width = value
       end
 

test/test_rdoc_options.rb

@@ -531,6 +531,26 @@ def test_parse_root
     assert_includes @options.rdoc_include, @options.root.to_s
   end
 
+  def test_parse_tab_width
+    @options.parse %w[--tab-width=1]
+    assert_equal 1, @options.tab_width
+
+    @options.parse %w[-w2]
+    assert_equal 2, @options.tab_width
+
+    _, err = capture_io do
+      @options.parse %w[-w=2]
+    end
+
+    assert_match 'invalid options', err
+
+    _, err = capture_io do
+      @options.parse %w[-w0]
+    end
+
+    assert_match 'invalid options', err
+  end
+
   def test_parse_template
     out, err = capture_io do
       @options.parse %w[--template darkfish]