Fix for rubocop#155. A bug in Semicolon#index_of_first_token_on_line.

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 ### Bugs fixed
 
+* [#155](https://github.com/bbatsov/rubocop/issues/155) 'Do not use semicolons to terminate expressions.' is not implemented correctly
+
 ## 0.7.1 (05/11/2013)
 
 ### Bugs fixed

lib/rubocop/cop/semicolon.rb

@@ -33,9 +33,10 @@ def inspect(file, source, tokens, sexp)
       def index_of_first_token_on_line(ix, lineno)
         # Index of last token on the previous line
         prev_line_ix =
-          @tokens[0...ix].rindex { |t| t.pos.lineno < lineno } || 0
+          @tokens[0...ix].rindex { |t| t.pos.lineno < lineno } || -1
+        first = prev_line_ix + 1
         # Index of first non-whitespace token on the current line.
-        prev_line_ix + @tokens[prev_line_ix..ix].index { |t| !whitespace?(t) }
+        first + @tokens[first..ix].index { |t| !whitespace?(t) }
       end
 
       def handle_exceptions_to_the_rule(token_1_ix)

spec/rubocop/cops/semicolon_spec.rb

@@ -81,8 +81,20 @@ module Cop
       it 'accepts one line empty class definitions' do
         inspect_source(s,
                        'file.rb',
-                       ['  class Foo < Exception; end',
-                        '  class Bar; end'])
+                       ['# Prefer a single-line format for class ...',
+                        'class Foo < Exception; end',
+                        '',
+                        'class Bar; end'])
+        expect(s.offences).to be_empty
+      end
+
+      it 'accepts one line empty method definitions' do
+        inspect_source(s,
+                       'file.rb',
+                       ['# One exception to the rule are empty-body methods',
+                        'def no_op; end',
+                        '',
+                        'def foo; end'])
         expect(s.offences).to be_empty
       end