fix spec for caching already optimised images

Author: toy

spec/image_optim/cache_spec.rb

@@ -69,7 +69,7 @@
           cached_s = cached.to_s
           expect(FileTest).to receive(:file?).with(cached_s).and_return(false)
           expect(FileTest).not_to receive(:size?).with(cached_s)
-          expect(FileUtils).to receive(:mv).with(anything, tmp_file)
+          expect(FileUtils).to receive(:mv).with(optimized, tmp_file)
           expect(tmp_file).to receive(:rename).with(cached)
 
           expect(cache.fetch(original){ optimized }).to eq(cached)
@@ -79,10 +79,10 @@
           cached_s = cached.to_s
           expect(FileTest).to receive(:file?).with(cached_s).and_return(false)
           expect(FileTest).not_to receive(:size?).with(cached_s)
-          expect(FileUtils).to receive(:mv).with(anything, tmp_file)
-          expect(tmp_file).to receive(:rename).with(cached)
+          expect(FileUtils).not_to receive(:mv)
+          expect(FileUtils).to receive(:touch).with(cached)
 
-          expect(cache.fetch(original){ optimized }).to eq(cached)
+          expect(cache.fetch(original){ nil }).to eq(nil)
         end
       end
     end
@@ -106,7 +106,7 @@
           expect(FileUtils).not_to receive(:mv)
           expect(File).not_to receive(:rename)
 
-          expect(cache.fetch(original){}).to eq(nil)
+          expect(cache.fetch(original){ nil }).to eq(nil)
         end
       end
     end