Allow ImageFormatter#== to factor width and height

This allows two Gitlab::Diff::Positions to be considered not equal when
their image position `width` or `height` properties are different.

lib/gitlab/diff/formatters/image_formatter.rb

@@ -37,7 +37,9 @@ module Gitlab
         def ==(other)
           other.is_a?(self.class) &&
             x == other.x &&
-            y == other.y
+            y == other.y &&
+            width == other.width &&
+            height == other.height
         end
       end
     end

spec/lib/gitlab/diff/formatters/image_formatter_spec.rb

@@ -3,20 +3,34 @@
 require 'spec_helper'
 
 describe Gitlab::Diff::Formatters::ImageFormatter do
-  it_behaves_like "position formatter" do
-    let(:base_attrs) do
-      {
-        base_sha: 123,
-        start_sha: 456,
-        head_sha: 789,
-        old_path: 'old_image.png',
-        new_path: 'new_image.png',
-        position_type: 'image'
-      }
-    end
+  let(:base_attrs) do
+    {
+      base_sha: 123,
+      start_sha: 456,
+      head_sha: 789,
+      old_path: 'old_image.png',
+      new_path: 'new_image.png',
+      position_type: 'image'
+    }
+  end
+
+  let(:attrs) do
+    base_attrs.merge(width: 100, height: 100, x: 1, y: 2)
+  end
+
+  it_behaves_like 'position formatter'
+
+  describe '#==' do
+    subject { described_class.new(attrs) }
+
+    it { is_expected.to eq(subject) }
+
+    [:width, :height, :x, :y].each do |attr|
+      let(:other_formatter) do
+        described_class.new(attrs.merge(attr => 9))
+      end
 
-    let(:attrs) do
-      base_attrs.merge(width: 100, height: 100, x: 1, y: 2)
+      it { is_expected.not_to eq(other_formatter) }
     end
   end
 end