improve trace logging in packages autoroller (#154441)

Add debugging to diagnose:
https://github.com/flutter/flutter/issues/154151

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

@@ -33,7 +33,7 @@ class Git {
     _reportFailureAndExit(args, workingDirectory, result, explanation);
   }
 
-  Future<int> run(
+  Future<ProcessResult> run(
     List<String> args,
     String explanation, {
     bool allowNonZeroExitCode = false,
@@ -48,7 +48,7 @@ class Git {
     if (result.exitCode != 0 && !allowNonZeroExitCode) {
       _reportFailureAndExit(args, workingDirectory, result, explanation);
     }
-    return result.exitCode;
+    return result;
   }
 
   Future<ProcessResult> _run(List<String> args, String workingDirectory) async {

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

@@ -140,7 +140,7 @@ This PR was generated by the automated
   }
 
   Future<void> _regenerateGradleLockfiles(Directory repoRoot) async {
-    await framework.runDart(<String>[
+    await framework.streamDart(<String>[
       '${repoRoot.path}/dev/tools/bin/generate_gradle_lockfiles.dart',
       '--no-gradle-generation',
       '--no-exclusion',
@@ -149,8 +149,10 @@ This PR was generated by the automated
       // If the git checkout is clean, we did not update any lockfiles and we do
       // not need an additional commit.
       case NoDiff():
+        stdio.printTrace('No diff after calling generate_gradle_lockfiles.dart');
         return;
       case OnlyLockfileChanges():
+        stdio.printTrace('Committing Gradle lockfile changes...');
         await framework.commit(
           'Re-generate Gradle lockfiles',
           addFirst: true,

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

@@ -380,7 +380,7 @@ abstract class Repository {
 
   /// Determines if one ref is an ancestor for another.
   Future<bool> isAncestor(String possibleAncestor, String possibleDescendant) async {
-    final int exitcode = await git.run(
+    final io.ProcessResult result = await git.run(
       <String>[
         'merge-base',
         '--is-ancestor',
@@ -391,18 +391,18 @@ abstract class Repository {
       allowNonZeroExitCode: true,
       workingDirectory: (await checkoutDirectory).path,
     );
-    return exitcode == 0;
+    return result.exitCode == 0;
   }
 
   /// Determines if a given commit has a tag.
   Future<bool> isCommitTagged(String commit) async {
-    final int exitcode = await git.run(
+    final io.ProcessResult result = await git.run(
       <String>['describe', '--exact-match', '--tags', commit],
       'verify $commit is already tagged',
       allowNonZeroExitCode: true,
       workingDirectory: (await checkoutDirectory).path,
     );
-    return exitcode == 0;
+    return result.exitCode == 0;
   }
 
   /// Resets repository HEAD to [ref].
@@ -480,16 +480,27 @@ abstract class Repository {
       }
       authorArg = '--author="$author"';
     }
-    await git.run(
+    final List<String> commitCmd = <String>[
-      <String>[
       'commit',
       '--message',
       message,
       if (authorArg != null) authorArg,
-      ],
+    ];
+    stdio.printTrace('Executing git $commitCmd...');
+    final io.ProcessResult commitResult = await git.run(
+      commitCmd,
       'commit changes',
       workingDirectory: (await checkoutDirectory).path,
     );
+    final String stdout = commitResult.stdout as String;
+    if (stdout.isNotEmpty) {
+      stdio.printTrace(stdout);
+    }
+    final String stderr = commitResult.stderr as String;
+    if (stderr.isNotEmpty) {
+      stdio.printTrace(stderr);
+    }
+
     return reverseParse('HEAD');
   }
 
@@ -608,13 +619,6 @@ class FrameworkRepository extends Repository {
     ]);
   }
 
-  Future<io.ProcessResult> runDart(List<String> args) async {
-    return processManager.run(<String>[
-      fileSystem.path.join((await checkoutDirectory).path, 'bin', 'dart'),
-      ...args,
-    ]);
-  }
-
   Future<io.ProcessResult> runFlutter(List<String> args) async {
     await _ensureToolReady();
     return processManager.run(<String>[
@@ -623,16 +627,27 @@ class FrameworkRepository extends Repository {
     ]);
   }
 
+  Future<void> streamDart(List<String> args) async => _streamProcess(<String>[
+    fileSystem.path.join((await checkoutDirectory).path, 'bin', 'dart'),
+    ...args,
+  ]);
+
   Future<io.Process> streamFlutter(
     List<String> args, {
     void Function(String)? stdoutCallback,
     void Function(String)? stderrCallback,
-  }) async {
+  }) async => _streamProcess(<String>[
-    await _ensureToolReady();
-    final io.Process process = await processManager.start(<String>[
     fileSystem.path.join((await checkoutDirectory).path, 'bin', 'flutter'),
     ...args,
   ]);
+
+  Future<io.Process> _streamProcess(
+    List<String> cmd, {
+    void Function(String)? stdoutCallback,
+    void Function(String)? stderrCallback,
+  }) async {
+    stdio.printTrace('Executing $cmd...');
+    final io.Process process = await processManager.start(cmd);
     process
         .stdout
         .transform(utf8.decoder)
@@ -643,6 +658,15 @@ class FrameworkRepository extends Repository {
         .transform(utf8.decoder)
         .transform(const LineSplitter())
         .listen(stderrCallback ?? stdio.printError);
+    final int exitCode = await process.exitCode;
+    if (exitCode != 0) {
+      throw io.ProcessException(
+        cmd.first,
+        cmd.sublist(1),
+        'Process failed',
+        exitCode,
+      );
+    }
     return process;
   }
 

dev/conductor/core/test/packages_autoroller_test.dart

@@ -293,10 +293,6 @@ void main() {
         '-b',
         'packages-autoroller-branch-1',
       ]),
-      const FakeCommand(command: <String>[
-        '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/bin/flutter',
-        'help',
-      ]),
       const FakeCommand(command: <String>[
         '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/bin/flutter',
         '--verbose',
@@ -389,10 +385,6 @@ void main() {
         '-b',
         'packages-autoroller-branch-1',
       ]),
-      const FakeCommand(command: <String>[
-        '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/bin/flutter',
-        'help',
-      ]),
       const FakeCommand(command: <String>[
         '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/bin/flutter',
         '--verbose',