Probably the tests were missing a link to the Core component - let's try this

Author: bpoplauschi

SDWebImageWebPCoderTests/Podfile

@@ -6,4 +6,5 @@ workspace '../SDWebImageWebPCoder'
 
 target 'SDWebImageWebPCoderTests' do
   pod 'SDWebImageWebPCoder', :path => '../'
+  pod 'SDWebImage'
 end