Include erb files for analysis, following Flay

This erb-processing code is lifted directly from flay:
https://github.com/seattlerb/flay/blob/master/lib/flay_erb.rb#L13

Add specs

Author: ABaldwinHunter

Diff for: .codeclimate.yml

@@ -8,6 +8,8 @@ engines:
     enabled: true
   duplication:
     enabled: true
+    exclude_fingerprints:
+    - b2dc8dbd27916d8321e298f59fc2f431 # Erubis < ::Erubis::Eruby
     config:
       languages:
       - ruby

Diff for: Gemfile

@@ -1,5 +1,6 @@
 source 'https://rubygems.org'
 
+gem 'erubis'
 gem 'flay', git: 'https://github.com/codeclimate/flay.git'
 gem 'concurrent-ruby', "~> 1.0.0"
 gem 'ruby_parser'

Diff for: Gemfile.lock

@@ -10,6 +10,7 @@ GEM
     coderay (1.1.0)
     concurrent-ruby (1.0.0)
     diff-lcs (1.2.5)
+    erubis (2.7.0)
     json (1.8.3)
     method_source (0.8.2)
     pry (0.10.3)
@@ -40,6 +41,7 @@ PLATFORMS
 
 DEPENDENCIES
   concurrent-ruby (~> 1.0.0)
+  erubis
   flay!
   json
   pry

Diff for: lib/cc/engine/analyzers/ruby/main.rb

@@ -1,3 +1,4 @@
+require "erubis"
 require "flay"
 require "json"
 require "cc/engine/analyzers/reporter"
@@ -10,12 +11,12 @@ module Ruby
         class Main < CC::Engine::Analyzers::Base
           LANGUAGE = "ruby"
           DEFAULT_PATHS = [
+            "**/*.erb",
             "**/*.rb",
             "**/*.rake",
             "**/Rakefile",
             "**/Gemfile",
             "**/*.gemspec"
-
           ]
           DEFAULT_MASS_THRESHOLD = 18
           BASE_POINTS = 1_500_000
@@ -33,7 +34,37 @@ def overage(mass)
           end
 
           def process_file(file)
-            RubyParser.new.process(File.binread(file), file, TIMEOUT)
+            if File.extname(file) == ".erb"
+              process_erb file
+            else
+              RubyParser.new.process(File.binread(file), file, TIMEOUT)
+            end
+          end
+
+          def process_erb(file)
+            erb = File.binread(file)
+            ruby = Erubis.new(erb).src
+            RubyParser.new.process(ruby, file)
+          end
+
+          class Erubis < ::Erubis::Eruby
+            BLOCK_EXPR = /\s+(do|\{)(\s*\|[^|]*\|)?\s*\Z/
+
+            def add_expr_literal(src, code)
+              if code =~ BLOCK_EXPR
+                src << "@output_buffer.append= " << code
+              else
+                src << "@output_buffer.append=(" << code << ");"
+              end
+            end
+
+            def add_expr_escaped(src, code)
+              if code =~ BLOCK_EXPR
+                src << "@output_buffer.safe_append= " << code
+              else
+                src << "@output_buffer.safe_append=(" << code << ");"
+              end
+            end
           end
         end
       end

Diff for: spec/cc/engine/analyzers/javascript/main_spec.rb

@@ -3,6 +3,7 @@
 require 'cc/engine/analyzers/reporter'
 require 'cc/engine/analyzers/engine_config'
 require 'cc/engine/analyzers/file_list'
+require 'erubis'
 
 RSpec.describe CC::Engine::Analyzers::Javascript::Main, in_tmpdir: true do
   include AnalyzerSpecHelpers

Diff for: spec/cc/engine/analyzers/ruby/main_spec.rb

@@ -88,6 +88,45 @@ module CC::Engine::Analyzers
           expect(run_engine(engine_conf)).to eq("")
         }.to output(/Skipping file/).to_stderr
       end
+
+      it "analyzes erb files" do
+        create_source_file("recipe.erb", <<-EOERB)
+<div class="container">
+  <h1>Select a Category</h1>
+  <ul>
+  <%categories.each do |category| %>
+  <li> <a href= "/category/<%=category.id%>"><%=category.name%> | <%=category.recipes.count%> Recipes </a></li>
+  <%end%>
+
+  <%categories.each do |category| %>
+    <li> <a href= "/category/<%=category.id%>"><%=category.name%> | <%=category.recipes.count%> Recipes </a></li>
+  <%end%>
+
+  <%categories.each do |category| %>
+    <li> <a href= "/category/<%=category.id%>"><%=category.name%> | <%=category.recipes.count%> Recipes </a></li>
+  <%end%>
+</ul>
+</div>
+        EOERB
+
+        issues = run_engine(engine_conf).strip.split("\0")
+        result = issues.first.strip
+        json = JSON.parse(result)
+
+        expect(json["type"]).to eq("issue")
+        expect(json["check_name"]).to eq("Similar code")
+        expect(json["description"]).to eq("Similar code found in 2 other locations (mass = 30)")
+        expect(json["categories"]).to eq(["Duplication"])
+        expect(json["location"]).to eq({
+          "path" => "recipe.erb",
+          "lines" => { "begin" => 4, "end" => 5 },
+        })
+        expect(json["remediation_points"]).to eq(2_700_000)
+        expect(json["other_locations"]).to eq([
+          {"path" => "recipe.erb", "lines" => { "begin" => 8, "end" => 9} },
+          {"path" => "recipe.erb", "lines" => { "begin" => 12, "end" => 13} }
+         ])
+      end
     end
 
     describe "#calculate_points(mass)" do