Merge pull request #311 from crystal-ameba/Sija/add-severity-color

Add `Severity#color`

src/ameba/formatter/dot_formatter.cr

@@ -49,7 +49,7 @@ module Ameba::Formatter
             issue.rule.severity.symbol,
             issue.rule.name,
             issue.message,
-          }).colorize(:red)
+          }).colorize(issue.rule.severity.color)
 
           if show_affected_code && (code = affected_code(issue))
             output << code.colorize(:default)

src/ameba/severity.cr

@@ -1,3 +1,5 @@
+require "colorize"
+
 module Ameba
   enum Severity
     Error
@@ -17,6 +19,19 @@ module Ameba
       end
     end
 
+    # Returns a color uniquely indicating severity.
+    #
+    # ```
+    # Severity::Warning.color # => Colorize::ColorANSI::Red
+    # ```
+    def color : Colorize::Color
+      case self
+      in Error      then Colorize::ColorANSI::Red
+      in Warning    then Colorize::ColorANSI::Red
+      in Convention then Colorize::ColorANSI::Blue
+      end
+    end
+
     # Creates Severity by the name.
     #
     # ```