Make doctor Xcode version requirement clearer (#88137)

packages/flutter_tools/lib/src/base/user_messages.dart

@@ -145,9 +145,14 @@ class UserMessages {
   // Messages used in XcodeValidator
   String xcodeLocation(String location) => 'Xcode at $location';
 
-  String xcodeOutdated(String currentVersion, String recommendedVersion) =>
-      'Xcode $currentVersion out of date ($recommendedVersion is recommended).\n'
+  String xcodeOutdated(String requiredVersion) =>
+      'Flutter requires a minimum Xcode version of $requiredVersion.\n'
       'Download the latest version or update via the Mac App Store.';
+
+  String xcodeRecommended(String recommendedVersion) =>
+      'Flutter recommends a minimum Xcode version of $recommendedVersion.\n'
+      'Download the latest version or update via the Mac App Store.';
+
   String get xcodeEula => "Xcode end user license agreement not signed; open Xcode or run the command 'sudo xcodebuild -license'.";
   String get xcodeMissingSimct =>
       'Xcode requires additional components to be installed in order to run.\n'

packages/flutter_tools/lib/src/macos/xcode_validator.dart

@@ -37,16 +37,10 @@ class XcodeValidator extends DoctorValidator {
 
       if (!_xcode.isInstalledAndMeetsVersionCheck) {
         xcodeStatus = ValidationType.partial;
-        messages.add(ValidationMessage.error(_userMessages.xcodeOutdated(
-          _xcode.currentVersion.toString(),
-          xcodeRecommendedVersion.toString(),
-        )));
+        messages.add(ValidationMessage.error(_userMessages.xcodeOutdated(xcodeRequiredVersion.toString())));
       } else if (!_xcode.isRecommendedVersionSatisfactory) {
         xcodeStatus = ValidationType.partial;
-        messages.add(ValidationMessage.hint(_userMessages.xcodeOutdated(
-          _xcode.currentVersion.toString(),
-          xcodeRecommendedVersion.toString(),
-        )));
+        messages.add(ValidationMessage.hint(_userMessages.xcodeRecommended(xcodeRecommendedVersion.toString())));
       }
 
       if (!_xcode.eulaSigned) {

packages/flutter_tools/test/general.shard/macos/xcode_validator_test.dart

@@ -55,20 +55,20 @@ void main() {
       final ValidationResult result = await validator.validate();
       expect(result.type, ValidationType.partial);
       expect(result.messages.last.type, ValidationMessageType.error);
-      expect(result.messages.last.message, contains('Xcode 7.0.1 out of date (12.0.1 is recommended)'));
+      expect(result.messages.last.message, contains('Flutter requires a minimum Xcode version of 12.0.1'));
     });
 
     testWithoutContext('Emits partial status when Xcode below recommended version', () async {
       final ProcessManager processManager = FakeProcessManager.any();
       final Xcode xcode = Xcode.test(
         processManager: processManager,
-        xcodeProjectInterpreter: XcodeProjectInterpreter.test(processManager: processManager, version: Version(11, 0, 0)),
+        xcodeProjectInterpreter: XcodeProjectInterpreter.test(processManager: processManager, version: Version(12, 0, 1)),
       );
       final XcodeValidator validator = XcodeValidator(xcode: xcode, userMessages: UserMessages());
       final ValidationResult result = await validator.validate();
       expect(result.type, ValidationType.partial);
       expect(result.messages.last.type, ValidationMessageType.hint);
-      expect(result.messages.last.message, contains('Xcode 11.0.0 out of date (12.0.1 is recommended)'));
+      expect(result.messages.last.message, contains('Flutter recommends a minimum Xcode version of 12.0.2'));
     }, skip: true); // [intended] Unskip and update when minimum and required check versions diverge.
 
     testWithoutContext('Emits partial status when Xcode EULA not signed', () async {