Support test matchers with only Vips

lib/carrierwave/test/matchers.rb

@@ -336,6 +336,8 @@ class ImageLoader # :nodoc:
         def self.load_image(filename)
           if defined? ::MiniMagick
             MiniMagickWrapper.new(filename)
+          elsif defined? ::Vips
+            VipsWrapper.new(filename)
           else
             unless defined? ::Magick
               begin
@@ -393,6 +395,28 @@ def initialize(filename)
         end
       end
 
+      class VipsWrapper # :nodoc:
+        attr_reader :image
+
+        def width
+          image.width
+        end
+
+        def height
+          image.height
+        end
+
+        def format
+          # This returns the name of the vips loader (e.g. pngload) as Vips
+          # doesn't do content detection.
+          image.get("vips-loader").delete_suffix("load")
+        end
+
+        def initialize(filename)
+          @image = ::Vips::Image.new_from_file(filename)
+        end
+      end
+
     end # Matchers
   end # Test
 end # CarrierWave