[Resolver] Added tests, notice if the required version exists in multiple…

[Resolver] Added tests, notice if the required version exists in multiple sources (CocoaPods/CocoaPods#2556)

lib/cocoapods/resolver.rb

@@ -149,6 +149,13 @@ module Pod
           set = find_cached_set(dependency, dependent_spec)
           set.required_by(dependency, dependent_spec.to_s)
 
+          unless set.sources.empty?
+            unless set.specification_paths_for_version(set.required_version).length == 1
+              UI.message("Found multiple specifications for #{dependency}:" \
+              "#{set.specification_paths_for_version(set.required_version).join(', ')}")
+            end 
+          end
+
           unless @loaded_specs.include?(dependency.name)
             spec = set.specification.subspec_by_name(dependency.name)
             @loaded_specs << spec.name
@@ -189,11 +196,10 @@ module Pod
           end
           set = Specification::Set::External.new(spec)
         else
-          set = find_set_from_sources(dependency)
+          set = create_set_from_sources(dependency)
         end
         cached_sets[name] = set
         unless set
-          binding.pry
           raise Informative, 'Unable to find a specification for ' \
             "`#{dependency}` depended upon by #{dependent_spec}."
         end
@@ -201,15 +207,16 @@ module Pod
       cached_sets[name]
     end
 
-    # @return [Set] Loads a set for the Pod of the given dependency from the
-    #         sources. The set will be limited to the versions of the first
-    #         source which includes the Pod.
+    # @return [Set] Creates a set for the Pod of the given dependency from the
+    #         sources. The set will contain all versions from all sources that
+    #         include the Pod.
     #
     # @param  [Dependency] dependency
     #         The dependency for which the set is needed.
     #
-    def find_set_from_sources(dependency)
+    def create_set_from_sources(dependency)
       matching_sources = sources.select { |source| source.pods.include? dependency.root_name }
+
       unless matching_sources.empty?
         return Specification::Set.new(dependency.root_name, matching_sources)
       end

spec/unit/resolver_spec.rb

@@ -237,17 +237,20 @@ COCOAPODS: 0.33.1
       it 'takes into account the order of the sources' do
         podfile = Podfile.new do
           platform :ios
-          pod 'JSONKit'
+          pod 'JSONKit', '1.4'
         end
         sources = SourcesManager.sources(%w(master test_repo))
         resolver = Resolver.new(config.sandbox, podfile, [], sources)
-        version = resolver.resolve.values.flatten.first.version
-        version.to_s.should.not == '999.999.999'
+        spec = resolver.resolve.values.flatten.first
+        spec.version.to_s.should == '1.4'
+        spec.defined_in_file.should == fixture('spec-repos/master/Specs/JSONKit/1.4/JSONKit.podspec.json')
 
         sources = SourcesManager.sources(%w(test_repo master))
         resolver = Resolver.new(config.sandbox, podfile, [], sources)
-        version = resolver.resolve.values.flatten.first.version
-        version.to_s.should == '999.999.999'
+        spec = resolver.resolve.values.flatten.first
+        spec.version.to_s.should == '1.4'
+        resolver.resolve.values.flatten.first.defined_in_file.should == fixture('spec-repos/test_repo/JSONKit/1.4/JSONKit.podspec')
+
       end
     end