use only one size? and no size calls on dst in default optimized? implementation, resolves #137

Author: toy

CHANGELOG.markdown

@@ -4,6 +4,7 @@
 
 * Add proper handling of `ImageOptim.respond_to?` [@toy](https://github.com/toy)
 * Fix an issue not working OptiPNG `interlace` option [#136](https://github.com/toy/image_optim/pull/136) [@mrk21](https://github.com/mrk21)
+* Minimize number of file system calls in default implementation of `optimized?` [#137](https://github.com/toy/image_optim/issues/137) [@toy](https://github.com/toy)
 
 ## v0.23.0 (2016-07-17)
 

lib/image_optim/worker.rb

@@ -73,7 +73,8 @@ def resolve_used_bins!
 
     # Check if operation resulted in optimized file
     def optimized?(src, dst)
-      dst.size? && dst.size < src.size
+      dst_size = dst.size?
+      dst_size && dst_size < src.size
     end
 
     # Short inspect

spec/image_optim/worker/optipng_spec.rb

@@ -59,8 +59,8 @@
   describe '#optimized?' do
     let(:src){ instance_double(ImageOptim::Path, src_options) }
     let(:dst){ instance_double(ImageOptim::Path, dst_options) }
-    let(:src_options){ {:size? => 10, :size => 10} }
-    let(:dst_options){ {:size? => 9, :size => 9} }
+    let(:src_options){ {:size => 10} }
+    let(:dst_options){ {:size? => 9} }
     let(:instance){ described_class.new(ImageOptim.new, instance_options) }
     let(:instance_options){ {} }
 
@@ -75,7 +75,7 @@
       end
 
       context 'when dst is not empty' do
-        let(:dst_options){ {:size? => 20, :size => 20} }
+        let(:dst_options){ {:size? => 20} }
         it{ is_expected.to be_truthy }
       end
     end
@@ -89,12 +89,12 @@
       end
 
       context 'when dst is greater than or equal to src' do
-        let(:dst_options){ {:size? => 10, :size => 10} }
+        let(:dst_options){ {:size? => 10} }
         it{ is_expected.to be_falsy }
       end
 
       context 'when dst is less than src' do
-        let(:dst_options){ {:size? => 9, :size => 9} }
+        let(:dst_options){ {:size? => 9} }
         it{ is_expected.to be_truthy }
       end
     end