Ensure `SWIFT_VERSION` is set for test only pod targets during validation

CHANGELOG.md

@@ -55,6 +55,10 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
 
 ##### Bug Fixes
 
+* Ensure `SWIFT_VERSION` is set for test only pod targets during validation  
+  [Dimitris Koutsogiorgas](https://github.com/dnkoutso)
+  [#7498](https://github.com/CocoaPods/CocoaPods/issues/7498)
+
 * Fix iOS test native target signing settings  
   [Dimitris Koutsogiorgas](https://github.com/dnkoutso)
   [#7504](https://github.com/CocoaPods/CocoaPods/pull/7504)

lib/cocoapods/validator.rb

@@ -506,13 +506,10 @@ module Pod
     end
 
     def configure_pod_targets(targets, deployment_target)
+      test_only_pod_targets = @installer.pod_targets - targets.flat_map(&:pod_targets)
       targets.each do |target|
         target.pod_targets.each do |pod_target|
-          next unless (native_target = pod_target.native_target)
-          native_target.build_configuration_list.build_configurations.each do |build_configuration|
-            (build_configuration.build_settings['OTHER_CFLAGS'] ||= '$(inherited)') << ' -Wincomplete-umbrella'
-            build_configuration.build_settings['SWIFT_VERSION'] = (pod_target.swift_version || swift_version) if pod_target.uses_swift?
-          end
+          update_pod_target_build_settings(pod_target)
           if pod_target.uses_swift?
             pod_target.test_native_targets.each do |test_native_target|
               test_native_target.build_configuration_list.build_configurations.each do |build_configuration|
@@ -527,6 +524,20 @@ module Pod
           error('swift', 'Swift support uses dynamic frameworks and is therefore only supported on iOS > 8.') unless uses_xctest
         end
       end
+      # Wire up Swift version to pod targets used only by tests.
+      test_only_pod_targets.each do |test_pod_target|
+        update_pod_target_build_settings(test_pod_target)
+      end
+    end
+
+    def update_pod_target_build_settings(pod_target)
+      native_target = pod_target.native_target
+      unless native_target.nil?
+        native_target.build_configuration_list.build_configurations.each do |build_configuration|
+          (build_configuration.build_settings['OTHER_CFLAGS'] ||= '$(inherited)') << ' -Wincomplete-umbrella'
+          build_configuration.build_settings['SWIFT_VERSION'] = (pod_target.swift_version || swift_version) if pod_target.uses_swift?
+        end
+      end
     end
 
     def validate_vendored_dynamic_frameworks

spec/unit/validator_spec.rb

@@ -1068,6 +1068,26 @@ module Pod
           pod_target_one = stub(:uses_swift? => true, :swift_version => '4.0', :native_target => native_target_one, :test_native_targets => [])
           pod_target_two = stub(:uses_swift? => true, :swift_version => '3.2', :native_target => native_target_two, :test_native_targets => [])
           aggregate_target = stub(:pod_targets => [pod_target_one, pod_target_two])
+          installer = stub(:pod_targets => [pod_target_one, pod_target_two])
+          validator.instance_variable_set(:@installer, installer)
+          validator.send(:configure_pod_targets, [aggregate_target], '9.0')
+          debug_configuration_one.build_settings['SWIFT_VERSION'].should == '4.0'
+          debug_configuration_two.build_settings['SWIFT_VERSION'].should == '3.2'
+        end
+
+        it 'honors swift version set by the pod target for dependencies that are not part of the aggregate target' do
+          validator = test_swiftpod
+          consumer = stub(:platform_name => 'iOS')
+          validator.instance_variable_set(:@consumer, consumer)
+          debug_configuration_one = stub(:build_settings => {})
+          debug_configuration_two = stub(:build_settings => {})
+          native_target_one = stub(:build_configuration_list => stub(:build_configurations => [debug_configuration_one]))
+          native_target_two = stub(:build_configuration_list => stub(:build_configurations => [debug_configuration_two]))
+          pod_target_one = stub(:uses_swift? => true, :swift_version => '4.0', :native_target => native_target_one, :test_native_targets => [])
+          pod_target_two = stub(:uses_swift? => true, :swift_version => '3.2', :native_target => native_target_two, :test_native_targets => [])
+          aggregate_target = stub(:pod_targets => [pod_target_one])
+          installer = stub(:pod_targets => [pod_target_one, pod_target_two])
+          validator.instance_variable_set(:@installer, installer)
           validator.send(:configure_pod_targets, [aggregate_target], '9.0')
           debug_configuration_one.build_settings['SWIFT_VERSION'].should == '4.0'
           debug_configuration_two.build_settings['SWIFT_VERSION'].should == '3.2'