Fix RuboCop to not report erroneous Style/EmptyElse warnings

When writing code like the following:

  - if condition
    :filter
      ...
  - else
    :filter
      ...

...if the filters contained no executable Ruby code the `RuboCop` linter
would incorrectly report a `Style/EmptyRule` warning due to the
`ScriptExtractor` not representing the filter in the extracted code.

Fix by always inserting a `puts` statement for filters.

Change-Id: Ia9f46c03dc923bee65a49258b62365d337509b75
Reviewed-on: http://gerrit.causes.com/47622
Tested-by: jenkins <jenkins@brigade.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>

CHANGELOG.md

@@ -5,8 +5,10 @@
 * Fix non-visible line number on light-colored terminal backgrounds
 * Allow files without `.haml` extension to be linted when explicitly specified
 * Ignore `Style/TrailingBlankLines` warnings from RuboCop by default
-* Fix RuboCop linter to not report `Style/AlignHash` warnings for HAML code with
-  1.8-style hash rockets spanning multiple lines
+* Fix `RuboCop` linter to not report `Style/AlignHash` warnings for HAML code
+  with 1.8-style hash rockets spanning multiple lines
+* Fix `RuboCop` linter to not report `Style/EmptyElse` warnings for HAML code
+  containing `if`/`else` blocks containing only HAML filters
 
 ## 0.11.0
 

lib/haml_lint/script_extractor.rb

@@ -103,6 +103,7 @@ def visit_filter(node)
           add_line(line, node.line + index + 1)
         end
       else
+        add_line('puts', node)
         HamlLint::Utils.extract_interpolated_values(node.text) do |interpolated_code|
           add_line(interpolated_code, node)
         end

spec/haml_lint/script_extractor_spec.rb

@@ -301,6 +301,7 @@
       HAML
 
       it { should == normalize_indent(<<-RUBY).rstrip }
+        puts
         some_method
         some_other_method
       RUBY
@@ -314,6 +315,7 @@
       HAML
 
       it { should == normalize_indent(<<-RUBY).rstrip }
+        puts
         some_method("hello")
         some_other_method('world')
       RUBY
@@ -329,9 +331,29 @@
       # TODO: Figure out if it's worth normalizing indentation for the generated
       # code in this interpolated context
       it { should == normalize_indent(<<-RUBY).rstrip }
+        puts
         some_method('hello',
                                  'world')
       RUBY
     end
+
+    context 'with an if/else block containing only filters' do
+      let(:haml) { <<-HAML }
+        - if condition
+          :filter
+            Some text
+        - else
+          :filter
+            Some other text
+      HAML
+
+      it { should == normalize_indent(<<-RUBY).rstrip }
+        if condition
+          puts
+        else
+          puts
+        end
+      RUBY
+    end
   end
 end