Add spec for 4bf3bf6786.

app/models/optimized_image.rb

@@ -252,9 +252,13 @@ class OptimizedImage < ActiveRecord::Base
     FileHelper.optimize_image!(to)
     true
   rescue => e
+    if Rails.env.test?
+      raise e
+    else
       Rails.logger.error("Could not optimize image #{to}: #{e.message}")
       false
     end
+  end
 
   def self.migrate_to_new_scheme(limit = nil)
     problems = []

spec/fixtures/images/svg.png

@@ -0,0 +1,3 @@
+<svg width="1" height="1">
+<image xlink:href="https://www.discourse.org" />
+</svg>

spec/models/optimized_image_spec.rb

@@ -45,6 +45,25 @@ describe OptimizedImage do
           File.delete(tmp_path) if File.exists?(tmp_path)
         end
       end
+
+      describe 'when an svg with a href is masked as a png' do
+        it 'should not trigger the external request' do
+          tmp_path = "/tmp/resized.png"
+
+          begin
+            expect do
+              OptimizedImage.resize(
+                "#{Rails.root}/spec/fixtures/images/svg.png",
+                tmp_path,
+                5,
+                5
+              )
+            end.to raise_error(RuntimeError, /improper image header/)
+          ensure
+            File.delete(tmp_path) if File.exists?(tmp_path)
+          end
+        end
+      end
     end
 
     describe '.downsize' do