add a check for env variable RELEASE_CHANNEL while generating docs (#86501)

* add a check for env variable RELEASE_CHANNEL in dev/snippets/lib/main.dart during doc generation
* update to LUCI_BRANCH, which is already populated
* validate env variable is either master or stable

dev/snippets/lib/main.dart

@@ -2,10 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:io';
+import 'dart:io' show exit, stderr, stdout, File, ProcessResult;
 
 import 'package:args/args.dart';
+import 'package:meta/meta.dart';
 import 'package:path/path.dart' as path;
+import 'package:platform/platform.dart';
+import 'package:process/process.dart';
 
 import 'configuration.dart';
 import 'snippets.dart';
@@ -30,9 +33,22 @@ class GitStatusFailed implements Exception {
   String toString() => 'git status exited with a non-zero exit code: ${gitResult.exitCode}:\n${gitResult.stderr}\n${gitResult.stdout}';
 }
 
-String getChannelName() {
+/// Get the name of the channel these docs are from.
+///
+/// First check env variable LUCI_BRANCH, then refer to the currently
+/// checked out git branch.
+String getChannelName({
+  @visibleForTesting
+  Platform platform = const LocalPlatform(),
+  @visibleForTesting
+  ProcessManager processManager = const LocalProcessManager(),
+}) {
+  final String? envReleaseChannel = platform.environment['LUCI_BRANCH']?.trim();
+  if (<String>['master', 'stable'].contains(envReleaseChannel)) {
+    return envReleaseChannel!;
+  }
   final RegExp gitBranchRegexp = RegExp(r'^## (?<branch>.*)');
-  final ProcessResult gitResult = Process.runSync('git', <String>['status', '-b', '--porcelain'],
+  final ProcessResult gitResult = processManager.runSync(<String>['git', 'status', '-b', '--porcelain'],
     environment: <String, String>{
       'GIT_TRACE': '2',
       'GIT_TRACE_SETUP': '2'
@@ -64,7 +80,8 @@ String getChannelNameWithRetries() {
 /// Generates snippet dartdoc output for a given input, and creates any sample
 /// applications needed by the snippet.
 void main(List<String> argList) {
-  final Map<String, String> environment = Platform.environment;
+  const Platform platform = LocalPlatform();
+  final Map<String, String> environment = platform.environment;
   final ArgParser parser = ArgParser();
   final List<String> snippetTypes =
       SnippetType.values.map<String>((SnippetType type) => getEnumName(type)).toList();

dev/snippets/pubspec.yaml

@@ -15,6 +15,7 @@ dependencies:
   dart_style: 2.0.2
   meta: 1.7.0
   platform: 3.0.0
+  process: 4.2.1
 
   _fe_analyzer_shared: 23.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   analyzer: 2.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
@@ -95,4 +96,4 @@ executables:
   vm_service_client: 0.2.6 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   web_socket_channel: 1.0.9 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
 
-# PUBSPEC CHECKSUM: 38c6
+# PUBSPEC CHECKSUM: ba17

dev/snippets/test/snippets_test.dart

@@ -3,10 +3,12 @@
 // found in the LICENSE file.
 
 import 'dart:convert';
-import 'dart:io' hide Platform;
-
+import 'dart:io' show Directory, File, Process, ProcessResult, ProcessSignal, ProcessStartMode, SystemEncoding;
 import 'package:path/path.dart' as path;
+import 'package:platform/platform.dart';
+import 'package:process/process.dart';
 import 'package:snippets/configuration.dart';
+import 'package:snippets/main.dart' show getChannelName;
 import 'package:snippets/snippets.dart';
 import 'package:test/test.dart' hide TypeMatcher, isInstanceOf;
 
@@ -215,4 +217,118 @@ void main() {
       expect(json['sourcePath'], equals('some/path.dart'));
     });
   });
+
+  group('getChannelName()', () {
+    test('does not call git if LUCI_BRANCH env var provided', () {
+      const String branch = 'stable';
+      final FakePlatform platform = FakePlatform(
+        environment: <String, String>{'LUCI_BRANCH': branch},
+      );
+      final FakeProcessManager processManager = FakeProcessManager(<FakeCommand>[]);
+      expect(
+        getChannelName(
+          platform: platform,
+          processManager: processManager,
+        ),
+        branch,
+      );
+      expect(processManager.hasRemainingExpectations, false);
+    });
+
+    test('calls git if LUCI_BRANCH env var is not provided', () {
+      const String branch = 'stable';
+      final FakePlatform platform = FakePlatform(
+        environment: <String, String>{},
+      );
+      final ProcessResult result = ProcessResult(0, 0, '## $branch...refs/heads/master', '');
+      final FakeProcessManager processManager = FakeProcessManager(
+        <FakeCommand>[FakeCommand('git status -b --porcelain', result)],
+      );
+      expect(
+        getChannelName(
+          platform: platform,
+          processManager: processManager,
+        ),
+        branch,
+      );
+      expect(processManager.hasRemainingExpectations, false);
+    });
+  });
+}
+
+const SystemEncoding systemEncoding = SystemEncoding();
+
+class FakeCommand {
+  FakeCommand(this.command, [ProcessResult? result]) : _result = result;
+  final String command;
+
+  final ProcessResult? _result;
+  ProcessResult get result => _result ?? ProcessResult(0, 0, '', '');
+}
+
+class FakeProcessManager implements ProcessManager {
+  FakeProcessManager(this.remainingExpectations);
+
+  final List<FakeCommand> remainingExpectations;
+
+  @override
+  bool canRun(dynamic command, {String? workingDirectory}) => true;
+
+  @override
+  Future<Process> start(
+    List<Object> command, {
+    String? workingDirectory,
+    Map<String, String>? environment,
+    bool includeParentEnvironment = true,
+    bool runInShell = false,
+    ProcessStartMode mode = ProcessStartMode.normal,
+  }) {
+    throw Exception('not implemented');
+  }
+
+  @override
+  Future<ProcessResult> run(
+    List<Object> command, {
+    String? workingDirectory,
+    Map<String, String>? environment,
+    bool includeParentEnvironment = true,
+    bool runInShell = false,
+    Encoding stdoutEncoding = systemEncoding,
+    Encoding stderrEncoding = systemEncoding,
+  }) {
+    throw Exception('not implemented');
+  }
+
+  @override
+  ProcessResult runSync(
+    List<Object> command, {
+    String? workingDirectory,
+    Map<String, String>? environment,
+    bool includeParentEnvironment = true,
+    bool runInShell = false,
+    Encoding stdoutEncoding = systemEncoding,
+    Encoding stderrEncoding = systemEncoding,
+  }) {
+    if (remainingExpectations.isEmpty) {
+      fail(
+        'Called FakeProcessManager with $command when no further commands were expected!',
+      );
+    }
+    final FakeCommand expectedCommand = remainingExpectations.removeAt(0);
+    final String expectedName = expectedCommand.command;
+    final String actualName = command.join(' ');
+    if (expectedName != actualName) {
+      fail(
+        'FakeProcessManager expected the command $expectedName but received $actualName',
+      );
+    }
+    return expectedCommand.result;
+  }
+
+  bool get hasRemainingExpectations => remainingExpectations.isNotEmpty;
+
+  @override
+  bool killPid(int pid, [ProcessSignal signal = ProcessSignal.sigterm]) {
+    throw Exception('not implemented');
+  }
 }