Only append a fake image extension if it's necessary.

lib/lita/handlers/google_images.rb

@@ -29,7 +29,7 @@ def fetch(response)
         if data["responseStatus"] == 200
           choice = data["responseData"]["results"].sample
           if choice
-            response.reply "#{choice["unescapedUrl"]}#.png"
+            response.reply ensure_extension(choice["unescapedUrl"])
           else
             response.reply %{No images found for "#{query}".}
           end
@@ -43,6 +43,14 @@ def fetch(response)
 
       private
 
+      def ensure_extension(url)
+        if [".gif", ".jpg", ".jpeg", ".png"].any? { |ext| url.end_with?(ext) }
+          url
+        else
+          "#{url}#.png"
+        end
+      end
+
       def safe_value
         safe = Lita.config.handlers.google_images.safe_search || "active"
         safe = safe.to_s.downcase

spec/lita/handlers/google_images_spec.rb

@@ -17,6 +17,26 @@
 
     it "replies with a matching image URL on success" do
       allow(response).to receive(:body).and_return(<<-JSON.chomp
+{
+  "responseStatus": 200,
+  "responseData": {
+    "results": [
+      {
+        "unescapedUrl": "http://www.example.com/path/to/an/image"
+      }
+    ]
+  }
+}
+JSON
+      )
+      send_command("image carl")
+      expect(replies.last).to eq(
+        "http://www.example.com/path/to/an/image#.png"
+      )
+    end
+
+    it "doesn't append a fake file extension if the image URL has a common image extension" do
+      allow(response).to receive(:body).and_return(<<-JSON.chomp
 {
   "responseStatus": 200,
   "responseData": {
@@ -31,7 +51,7 @@
       )
       send_command("image carl")
       expect(replies.last).to eq(
-        "http://www.example.com/path/to/an/image.jpg#.png"
+        "http://www.example.com/path/to/an/image.jpg"
       )
     end