Merge pull request #7326 from CocoaPods/seg-resolver-multi-source-ordering

 [Resolver] Fix multi-source resolution

CHANGELOG.md

@@ -22,6 +22,11 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
   [Dimitris Koutsogiorgas](https://github.com/dnkoutso)
   [#7292](https://github.com/CocoaPods/CocoaPods/pull/7292)
 
+* Fix resolution when multiple sources provide the same pods, and there are 
+  (potential) dependencies between the sources.  
+  [Samuel Giddins](https://github.com/segiddins)
+  [#7031](https://github.com/CococaPods/CocoaPods/issues/7031)
+
 ## 1.4.0.rc.1 (2017-12-16)
 
 ##### Enhancements

lib/cocoapods/resolver.rb

@@ -351,8 +351,7 @@ module Pod
         all_specifications(installation_options.warn_for_multiple_pod_sources).
         select { |s| requirement.satisfied_by? s.version }.
         map { |s| s.subspec_by_name(dependency.name, false, true) }.
-        compact.
-        reverse
+        compact
     end
 
     # @return [Set] Loads or returns a previously initialized set for the Pod
@@ -508,7 +507,7 @@ module Pod
           end,
         )
       end
-      raise type, message
+      raise type.new(message).tap { |e| e.set_backtrace(error.backtrace) }
     end
 
     # Returns whether the given spec is platform-compatible with the dependency

lib/cocoapods/resolver/lazy_specification.rb

@@ -37,12 +37,12 @@ module Pod
         end
       end
 
+      # returns the highest versioned spec last
       def all_specifications(warn_for_multiple_pod_sources)
         @all_specifications ||= begin
           sources_by_version = {}
           versions_by_source.each do |source, versions|
             versions.each { |v| (sources_by_version[v] ||= []) << source }
-            sources_by_version
           end
 
           if warn_for_multiple_pod_sources
@@ -56,8 +56,11 @@ module Pod
             end
           end
 
-          versions_by_source.flat_map do |source, versions|
-            versions.map { |version| LazySpecification.new(name, version, source) }
+          # sort versions from high to low
+          sources_by_version.sort_by(&:first).flat_map do |version, sources|
+            # within each version, we want the prefered (first-specified) source
+            # to be the _last_ one
+            sources.reverse_each.map { |source| LazySpecification.new(name, version, source) }
           end
         end
       end

spec/unit/resolver_spec.rb

@@ -13,6 +13,68 @@ end
 
 module Pod
   describe Resolver do
+    class MockSource < Source
+      attr_reader :name
+
+      def initialize(name, &blk)
+        @name = name
+        @_pods_by_name = Hash.new { |h, k| h[k] = [] }
+        @_current_pod = nil
+        instance_eval(&blk)
+        super('/mock/repo')
+      end
+
+      def pod(name, version = nil, platform: [[:ios, '9.0']], test_spec: false, &_blk)
+        cp = @_current_pod
+        Pod::Specification.new(cp, name, test_spec) do |spec|
+          @_current_pod = spec
+          if cp
+            cp.subspecs << spec
+          else
+            spec.version = version
+          end
+          platform.each { |pl, dt| spec.send(pl).deployment_target = dt }
+          yield spec if block_given?
+        end
+        @_pods_by_name[name] << @_current_pod if cp.nil?
+      ensure
+        @_current_pod = cp
+      end
+
+      def test_spec(name: 'Tests', &blk)
+        pod(name, :test_spec => true, &blk)
+      end
+
+      def all_specs
+        @_pods_by_name.values.flatten(1)
+      end
+
+      def pods
+        @_pods_by_name.keys
+      end
+
+      def search(query)
+        query = query.root_name if query.is_a?(Dependency)
+        set(query) if @_pods_by_name.key?(query)
+      end
+
+      def specification(name, version)
+        @_pods_by_name[name].find { |s| s.version == Pod::Version.new(version) }
+      end
+
+      def versions(name)
+        @_pods_by_name[name].map(&:version)
+      end
+
+      def specification_path(name, version)
+        pod_path(name).join(version.to_s, "#{name}.podspec")
+      end
+
+      def specs_dir
+        repo
+      end
+    end
+
     describe 'In general' do
       before do
         @podfile = Podfile.new do
@@ -675,6 +737,54 @@ Note: as of CocoaPods 1.0, `pod repo update` does not happen on `pod install` by
         UI.warnings.should.match /multiple specifications/
       end
 
+      it 'chooses the first source in a complicated scenario' do
+        test_repo1 = MockSource.new('test_repo1') do
+          pod 'Core', '1.0.0' do
+            test_spec
+          end
+          pod 'Core', '1.0.1' do
+            test_spec
+          end
+          pod 'Data', '1.0.0' do |s|
+            s.dependency 'Core', '~> 1.0'
+            test_spec { |ts| ts.dependency 'Testing', '~> 1.0' }
+          end
+          pod 'Data', '1.0.1' do |s|
+            s.dependency 'Core', '~> 1.0'
+            test_spec { |ts| ts.dependency 'Testing', '~> 1.0' }
+          end
+          pod 'Testing', '1.0.0' do |s|
+            s.dependency 'Core'
+          end
+          pod 'Testing', '1.0.1' do |s|
+            s.dependency 'Core'
+          end
+        end
+
+        test_repo2 = MockSource.new('test_repo2') do
+          pod 'Core', '1.0.1' do
+            test_spec
+          end
+          pod 'Data', '1.0.1' do |s|
+            s.dependency 'Core', '~> 1.0'
+            test_spec { |ts| ts.dependency 'Testing', '~> 1.0' }
+          end
+          pod 'Testing', '1.0.1' do |s|
+            s.dependency 'Core'
+          end
+        end
+        sources = [test_repo1, test_repo2]
+        podfile = Podfile.new do
+          platform :ios, '9.0'
+          pod 'Data/Tests', '~> 1.0'
+          pod 'Data', '~> 1.0'
+        end
+
+        resolver = Resolver.new(config.sandbox, podfile, empty_graph, sources)
+        resolver.resolve.values.flatten.map { |rs| rs.spec.to_s }.sort.
+          should == ['Core (1.0.1)', 'Data (1.0.1)', 'Data/Tests (1.0.1)', 'Testing (1.0.1)']
+      end
+
       it 'does not warn when multiple sources contain a pod but a dependency ' \
          'has an explicit source specified' do
         test_repo_url = config.sources_manager.source_with_name_or_url('test_repo').url