Render diff of messages

Author: oowekyala

lib/pmdtester/builders/diff_report/violations.rb

@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+require 'differ'
 
 # Contains methods to write out html for the violations.
 # This mixin is used by DiffReportBuilder.
@@ -59,7 +60,11 @@ def build_violation_table_row(doc, key, pmd_violation)
       end
 
       # The violation message
-      doc.td "\n" + pmd_violation.text + "\n"
+      if pmd_violation.changed
+        doc.td { diff_fragments(doc, pmd_violation) }
+      else
+        doc.td pmd_violation.text
+      end
 
       # The begin line of the violation
       line = violation['beginline']
@@ -72,6 +77,13 @@ def build_violation_table_row(doc, key, pmd_violation)
     end
   end
 
+  def diff_fragments(doc, violation)
+    old_message = violation.attrs["oldMessage"]
+    new_message = violation.text
+    diff = Differ.diff_by_word(old_message, new_message)
+    doc << diff.format_as(:html)
+  end
+
   def get_link_to_source(violation, key)
     l_str = @project.type == 'git' ? 'L' : 'l'
     line_str = "##{l_str}#{violation['beginline']}"