[conductor] channel constants refactor (#94220)

dev/conductor/core/lib/src/globals.dart

@@ -12,12 +12,11 @@ const String gsutilBinary = 'gsutil.py';
 const String kFrameworkDefaultBranch = 'master';
 const String kForceFlag = 'force';
 
-const List<String> kReleaseChannels = <String>[
-  'stable',
-  'beta',
-  'dev',
-  FrameworkRepository.defaultBranch,
-];
+const List<String> kBaseReleaseChannels = <String>['stable', 'beta', 'dev'];
+
+const List<String> kReleaseChannels = <String>[...kBaseReleaseChannels, FrameworkRepository.defaultBranch];
+
+const List<String> KReleaseIncrements = <String>['y', 'z', 'm', 'n'];
 
 const String kReleaseDocumentationUrl = 'https://github.com/flutter/flutter/wiki/Flutter-Cherrypick-Process';
 
@@ -80,8 +79,7 @@ String? getValueFromEnvOrArgs(
   if (allowNull) {
     return null;
   }
-  throw ConductorException(
-    'Expected either the CLI arg --$name or the environment variable $envName '
+  throw ConductorException('Expected either the CLI arg --$name or the environment variable $envName '
       'to be provided!');
 }
 
@@ -120,8 +118,7 @@ List<String> getValuesFromEnvOrArgs(
     return argValues;
   }
 
-  throw ConductorException(
-    'Expected either the CLI arg --$name or the environment variable $envName '
+  throw ConductorException('Expected either the CLI arg --$name or the environment variable $envName '
       'to be provided!');
 }
 

dev/conductor/core/lib/src/start.dart

@@ -48,7 +48,7 @@ class StartCommand extends Command<void> {
     argParser.addOption(
       kReleaseOption,
       help: 'The target release channel for the release.',
-      allowed: <String>['stable', 'beta', 'dev'],
+      allowed: kBaseReleaseChannels,
     );
     argParser.addOption(
       kFrameworkUpstreamOption,
@@ -93,7 +93,7 @@ class StartCommand extends Command<void> {
       kIncrementOption,
       help: 'Specifies which part of the x.y.z version number to increment. Required.',
       valueHelp: 'level',
-      allowed: <String>['y', 'z', 'm', 'n'],
+      allowed: KReleaseIncrements,
       allowedHelp: <String, String>{
         'y': 'Indicates the first dev release after a beta release.',
         'z': 'Indicates a hotfix to a stable release.',

dev/conductor/core/lib/src/state.dart

@@ -15,7 +15,7 @@ const String kStateFileName = '.flutter_conductor_state.json';
 
 String luciConsoleLink(String channel, String groupName) {
   assert(
-    <String>['stable', 'beta', 'dev', 'master'].contains(channel),
+    kReleaseChannels.contains(channel),
     'channel $channel not recognized',
   );
   assert(

dev/conductor/core/lib/src/version.dart

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import './globals.dart' show releaseCandidateBranchRegex, ConductorException;
+import './globals.dart' show ConductorException, KReleaseIncrements, releaseCandidateBranchRegex;
 
 /// Possible string formats that `flutter --version` can return.
 enum VersionType {
@@ -262,7 +262,7 @@ class Version {
   /// Will throw a [ConductorException] if the version is not possible given the
   /// [candidateBranch] and [incrementLetter].
   void ensureValid(String candidateBranch, String incrementLetter) {
-    if (!const <String>{'y', 'z', 'm', 'n'}.contains(incrementLetter)) {
+    if (!KReleaseIncrements.contains(incrementLetter)) {
       throw ConductorException('Invalid incrementLetter: $incrementLetter');
     }
     final RegExpMatch? branchMatch = releaseCandidateBranchRegex.firstMatch(candidateBranch);