[action][spm] add simulator flag for swift compiler

fastlane/lib/fastlane/actions/spm.rb

@@ -10,6 +10,15 @@ def self.run(params)
         cmd << "--configuration #{params[:configuration]}" if params[:configuration]
         cmd << "--disable-sandbox" if params[:disable_sandbox]
         cmd << "--verbose" if params[:verbose]
+        if params[:simulator]
+          simulator_flags = [
+            "-Xswiftc", "-sdk",
+            "-Xswiftc", "$(xcrun --sdk #{params[:simulator]} --show-sdk-path)",
+            "-Xswiftc", "-target",
+            "-Xswiftc", "x86_64-apple-ios$(xcrun --sdk #{params[:simulator]} --show-sdk-version | cut -d '.' -f 1)-simulator"
+          ]
+          cmd += simulator_flags
+        end
         cmd << params[:command] if package_commands.include?(params[:command])
         cmd << "--enable-code-coverage" if params[:enable_code_coverage] && (params[:command] == 'generate-xcodeproj' || params[:command] == 'test')
         if params[:xcconfig]
@@ -93,7 +102,15 @@ def self.available_options
                                        env_name: "FL_SPM_VERBOSE",
                                        description: "Increase verbosity of informational output",
                                        type: Boolean,
-                                       default_value: false)
+                                       default_value: false),
+          FastlaneCore::ConfigItem.new(key: :simulator,
+                                       env_name: "FL_SPM_SIMULATOR",
+                                       description: "Specifies the simulator to pass for Swift Compiler (one of: #{valid_simulators.join(', ')})",
+                                       type: String,
+                                       optional: true,
+                                       verify_block: proc do |value|
+                                         UI.user_error!("Please pass a valid simulator. Use one of the following: #{valid_simulators.join(', ')}") unless valid_simulators.include?(value)
+                                       end)
         ]
       end
 
@@ -139,6 +156,10 @@ def self.valid_configurations
       def self.xcpretty_output_types
         %w(simple test knock tap)
       end
+
+      def self.valid_simulators
+        %w(iphonesimulator macossimulator)
+      end
     end
   end
 end

fastlane/spec/actions_specs/spm_spec.rb

@@ -339,6 +339,43 @@
           expect(result).to eq("set -o pipefail && swift package --verbose generate-xcodeproj --xcconfig-overrides Package.xcconfig 2>&1 | xcpretty --simple")
         end
       end
+
+      context "when simulator is specified" do
+        it "adds simulator flags to the build command" do
+          result = Fastlane::FastFile.new.parse("lane :test do
+              spm(
+                command: 'build',
+                simulator: 'iphonesimulator'
+              )
+            end").runner.execute(:test)
+
+          expect(result).to eq("swift build -Xswiftc -sdk -Xswiftc $(xcrun --sdk iphonesimulator --show-sdk-path) -Xswiftc -target -Xswiftc x86_64-apple-ios$(xcrun --sdk iphonesimulator --show-sdk-version | cut -d '.' -f 1)-simulator")
+        end
+
+        it "raises an error if simulator syntax is invalid" do
+          expect do
+            Fastlane::FastFile.new.parse("lane :test do
+              spm(
+                command: 'build',
+                simulator: 'invalid_simulator'
+              )
+            end").runner.execute(:test)
+          end.to raise_error("Invalid simulator syntax. Please use 'iphonesimulator', 'ipadsimulator', or 'macossimulator'.")
+        end
+      end
+
+      context "when simulator is specified for non-package commands" do
+        it "raises an error" do
+          expect do
+            Fastlane::FastFile.new.parse("lane :test do
+              spm(
+                command: 'clean',
+                simulator: 'iphonesimulator'
+              )
+            end").runner.execute(:test)
+          end.to raise_error("Simulator is only applicable to package-related commands.")
+        end
+      end
     end
   end
 end