Provide debug output for Gold uploads on post-submit (#45704)

Author: Piinks

packages/flutter_goldens/lib/flutter_goldens.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 import 'dart:io' as io;
+import 'dart:math' as math;
 import 'dart:typed_data';
 
 import 'package:file/file.dart';
@@ -130,15 +131,15 @@ abstract class FlutterGoldenFileComparator extends GoldenFileComparator {
   /// Calculate the appropriate basedir for the current test context.
   @protected
   @visibleForTesting
-  static Directory getBaseDirectory(LocalFileComparator defaultComparator, Platform platform) {
+  static Directory getBaseDirectory(LocalFileComparator defaultComparator, Platform platform, {String suffix = ''}) {
     const FileSystem fs = LocalFileSystem();
     final Directory flutterRoot = fs.directory(platform.environment[_kFlutterRootKey]);
     final Directory comparisonRoot = flutterRoot.childDirectory(
       fs.path.join(
         'bin',
         'cache',
         'pkg',
-        'skia_goldens',
+        'skia_goldens$suffix',
       )
     );
     final Directory testDirectory = fs.directory(defaultComparator.basedir);
@@ -214,6 +215,7 @@ class FlutterSkiaGoldFileComparator extends FlutterGoldenFileComparator {
     final Directory baseDirectory = FlutterGoldenFileComparator.getBaseDirectory(
       defaultComparator,
       platform,
+      suffix: '${math.Random().nextInt(10000)}',
     );
 
     if(!baseDirectory.existsSync()) {

packages/flutter_goldens_client/lib/skia_client.dart

@@ -121,10 +121,15 @@ class SkiaGoldClient {
         .path,
     ];
 
-    await io.Process.run(
+    final io.ProcessResult result = await io.Process.run(
       _goldctl,
       authArguments,
     );
+
+    if (result.exitCode != 0) {
+      print('goldctl auth stdout: ${result.stdout}');
+      print('goldctl auth stderr: ${result.stderr}');
+    }
   }
 
   /// Executes the `imgtest init` command in the goldctl tool.
@@ -158,10 +163,15 @@ class SkiaGoldClient {
       throw NonZeroExitCode(1, buf.toString());
     }
 
-    await io.Process.run(
+    final io.ProcessResult result = await io.Process.run(
       _goldctl,
       imgtestInitArguments,
     );
+
+    if (result.exitCode != 0) {
+      print('goldctl imgtest init stdout: ${result.stdout}');
+      print('goldctl imgtest init stderr: ${result.stderr}');
+    }
   }
 
   /// Executes the `imgtest add` command in the goldctl tool.
@@ -186,10 +196,16 @@ class SkiaGoldClient {
       '--png-file', goldenFile.path,
     ];
 
-    await io.Process.run(
+    final io.ProcessResult result = await io.Process.run(
       _goldctl,
       imgtestArguments,
     );
+
+    if (result.exitCode != 0) {
+      print('goldctl imgtest add stdout: ${result.stdout}');
+      print('goldctl imgtest add stderr: ${result.stderr}');
+    }
+
     return true;
   }