FIX: Show a correct diff when editing consecutive paragraphs (#8177)

spec/components/onpdiff_spec.rb

@@ -39,4 +39,38 @@ describe ONPDiff do
 
   end
 
+  describe "paragraph_diff" do
+
+    it "returns an empty array when there is no content to diff" do
+      expect(ONPDiff.new("", "").paragraph_diff).to eq([])
+    end
+
+    it "returns an array with the operation code for each element" do
+      expect(ONPDiff.new("abc", "acd").paragraph_diff).to eq([["a", :common], ["b", :delete], ["c", :common], ["d", :add]])
+    end
+
+    it "pairs as many elements as possible", :focus do
+      expect(ONPDiff.new("abcd", "abef").paragraph_diff).to eq([
+        ["a", :common], ["b", :common],
+        ["e", :add], ["c", :delete],
+        ["f", :add], ["d", :delete]
+      ])
+
+      expect(ONPDiff.new("abcde", "abfg").paragraph_diff).to eq([
+        ["a", :common], ["b", :common],
+        ["c", :delete],
+        ["d", :delete], ["f", :add],
+        ["e", :delete], ["g", :add]
+      ])
+
+      expect(ONPDiff.new("abcd", "abefg").paragraph_diff).to eq([
+        ["a", :common], ["b", :common],
+        ["e", :add],
+        ["f", :add], ["c", :delete],
+        ["g", :add], ["d", :delete]
+      ])
+    end
+
+  end
+
 end