Add more logs to diagnose Gold flake (#108930)

packages/flutter_goldens/test/flutter_goldens_test.dart

@@ -489,6 +489,94 @@ void main() {
       );
     });
 
+    test('throws for error state from imgtestAdd', () {
+      final File goldenFile = fs.file('/workDirectory/temp/golden_file_test.png')
+        ..createSync(recursive: true);
+      platform = FakePlatform(
+          environment: <String, String>{
+            'FLUTTER_ROOT': _kFlutterRoot,
+            'GOLDCTL' : 'goldctl',
+          },
+          operatingSystem: 'macos'
+      );
+
+      skiaClient = SkiaGoldClient(
+        workDirectory,
+        fs: fs,
+        process: process,
+        platform: platform,
+        httpClient: fakeHttpClient,
+      );
+
+      const RunInvocation goldctlInvocation = RunInvocation(
+        <String>[
+          'goldctl',
+          'imgtest', 'add',
+          '--work-dir', '/workDirectory/temp',
+          '--test-name', 'golden_file_test',
+          '--png-file', '/workDirectory/temp/golden_file_test.png',
+          '--passfail',
+        ],
+        null,
+      );
+      process.processResults[goldctlInvocation] = ProcessResult(123, 1, 'Expected failure', 'Expected failure');
+      process.fallbackProcessResult = ProcessResult(123, 1, 'Fallback failure', 'Fallback failure');
+
+      expect(
+          skiaClient.imgtestAdd('golden_file_test', goldenFile),
+        throwsA(
+          isA<SkiaException>().having((SkiaException error) => error.message,
+            'message',
+            contains('result-state.json'),
+          ),
+        ),
+      );
+    });
+
+    test('throws for error state from tryjobAdd', () {
+      final File goldenFile = fs.file('/workDirectory/temp/golden_file_test.png')
+        ..createSync(recursive: true);
+      platform = FakePlatform(
+          environment: <String, String>{
+            'FLUTTER_ROOT': _kFlutterRoot,
+            'GOLDCTL' : 'goldctl',
+          },
+          operatingSystem: 'macos'
+      );
+
+      skiaClient = SkiaGoldClient(
+        workDirectory,
+        fs: fs,
+        process: process,
+        platform: platform,
+        httpClient: fakeHttpClient,
+      );
+
+      const RunInvocation goldctlInvocation = RunInvocation(
+        <String>[
+          'goldctl',
+          'imgtest', 'add',
+          '--work-dir', '/workDirectory/temp',
+          '--test-name', 'golden_file_test',
+          '--png-file', '/workDirectory/temp/golden_file_test.png',
+          '--passfail',
+        ],
+        null,
+      );
+      process.processResults[goldctlInvocation] = ProcessResult(123, 1, 'Expected failure', 'Expected failure');
+      process.fallbackProcessResult = ProcessResult(123, 1, 'Fallback failure', 'Fallback failure');
+
+      expect(
+        skiaClient.tryjobAdd('golden_file_test', goldenFile),
+        throwsA(
+          isA<SkiaException>().having((SkiaException error) => error.message,
+            'message',
+            contains('result-state.json'),
+          ),
+        ),
+      );
+    });
+
     group('Request Handling', () {
       const String expectation = '55109a4bed52acc780530f7a9aeff6c0';
 

packages/flutter_goldens_client/lib/skia_client.dart

@@ -21,6 +21,21 @@ const String _kGoldctlKey = 'GOLDCTL';
 const String _kTestBrowserKey = 'FLUTTER_TEST_BROWSER';
 const String _kWebRendererKey = 'FLUTTER_WEB_RENDERER';
 
+/// Exception thrown when an error is returned from the [SkiaClient].
+class SkiaException implements Exception {
+  /// Creates a new `SkiaException` with a required error [message].
+  const SkiaException(this.message);
+
+  /// A message describing the error.
+  final String message;
+
+  /// Returns a description of the Skia exception.
+  ///
+  /// The description always contains the [message].
+  @override
+  String toString() => 'SkiaException: $message';
+}
+
 /// A client for uploading image tests and making baseline requests to the
 /// Flutter Gold Dashboard.
 class SkiaGoldClient {
@@ -103,10 +118,10 @@ class SkiaGoldClient {
         ..writeln('Luci environments authenticate using the file provided '
           'by LUCI_CONTEXT. There may be an error with this file or Gold '
           'authentication.')
-        ..writeln('Debug information for Gold:')
+        ..writeln('Debug information for Gold --------------------------------')
         ..writeln('stdout: ${result.stdout}')
         ..writeln('stderr: ${result.stderr}');
-      throw Exception(buf.toString());
+      throw SkiaException(buf.toString());
     }
   }
 
@@ -155,7 +170,7 @@ class SkiaGoldClient {
         ..writeln('Please confirm the settings of your golden file test.')
         ..writeln('Arguments provided:');
       imgtestInitCommand.forEach(buf.writeln);
-      throw Exception(buf.toString());
+      throw SkiaException(buf.toString());
     }
 
     final io.ProcessResult result = await process.run(imgtestInitCommand);
@@ -167,10 +182,10 @@ class SkiaGoldClient {
         ..writeln('An error occurred when initializing golden file test with ')
         ..writeln('goldctl.')
         ..writeln()
-        ..writeln('Debug information for Gold:')
+        ..writeln('Debug information for Gold --------------------------------')
         ..writeln('stdout: ${result.stdout}')
         ..writeln('stderr: ${result.stderr}');
-      throw Exception(buf.toString());
+      throw SkiaException(buf.toString());
     }
     _initialized = true;
   }
@@ -202,6 +217,14 @@ class SkiaGoldClient {
     if (result.exitCode != 0) {
       // If an unapproved image has made it to post-submit, throw to close the
       // tree.
+      String? resultContents;
+      final File resultFile = workDirectory.childFile(fs.path.join(
+        'result-state.json',
+      ));
+      if(await resultFile.exists()) {
+        resultContents = await resultFile.readAsString();
+      }
+
       final StringBuffer buf = StringBuffer()
         ..writeln('Skia Gold received an unapproved image in post-submit ')
         ..writeln('testing. Golden file images in flutter/flutter are triaged ')
@@ -212,10 +235,12 @@ class SkiaGoldClient {
         ..writeln('information, visit the wiki: ')
         ..writeln('https://github.com/flutter/flutter/wiki/Writing-a-golden-file-test-for-package:flutter')
         ..writeln()
-        ..writeln('Debug information for Gold:')
+        ..writeln('Debug information for Gold --------------------------------')
         ..writeln('stdout: ${result.stdout}')
-        ..writeln('stderr: ${result.stderr}');
-      throw Exception(buf.toString());
+        ..writeln('stderr: ${result.stderr}')
+        ..writeln()
+        ..writeln('result-state.json: ${resultContents ?? 'No result file found.'}');
+      throw SkiaException(buf.toString());
     }
 
     return true;
@@ -269,7 +294,7 @@ class SkiaGoldClient {
         ..writeln('Please confirm the settings of your golden file test.')
         ..writeln('Arguments provided:');
       imgtestInitCommand.forEach(buf.writeln);
-      throw Exception(buf.toString());
+      throw SkiaException(buf.toString());
     }
 
     final io.ProcessResult result = await process.run(imgtestInitCommand);
@@ -281,10 +306,10 @@ class SkiaGoldClient {
         ..writeln('An error occurred when initializing golden file tryjob with ')
         ..writeln('goldctl.')
         ..writeln()
-        ..writeln('Debug information for Gold:')
+        ..writeln('Debug information for Gold --------------------------------')
         ..writeln('stdout: ${result.stdout}')
         ..writeln('stderr: ${result.stderr}');
-      throw Exception(buf.toString());
+      throw SkiaException(buf.toString());
     }
     _tryjobInitialized = true;
   }
@@ -315,16 +340,25 @@ class SkiaGoldClient {
     final String/*!*/ resultStdout = result.stdout.toString();
     if (result.exitCode != 0 &&
       !(resultStdout.contains('Untriaged') || resultStdout.contains('negative image'))) {
+      String? resultContents;
+      final File resultFile = workDirectory.childFile(fs.path.join(
+        'result-state.json',
+      ));
+      if(await resultFile.exists()) {
+        resultContents = await resultFile.readAsString();
+      }
       final StringBuffer buf = StringBuffer()
         ..writeln('Unexpected Gold tryjobAdd failure.')
         ..writeln('Tryjob execution for golden file test $testName failed for')
         ..writeln('a reason unrelated to pixel comparison.')
         ..writeln()
-        ..writeln('Debug information for Gold:')
+        ..writeln('Debug information for Gold --------------------------------')
         ..writeln('stdout: ${result.stdout}')
         ..writeln('stderr: ${result.stderr}')
-        ..writeln();
-      throw Exception(buf.toString());
+        ..writeln()
+        ..writeln()
+        ..writeln('result-state.json: ${resultContents ?? 'No result file found.'}');
+      throw SkiaException(buf.toString());
     }
   }
 
@@ -432,14 +466,14 @@ class SkiaGoldClient {
   /// Returns the current commit hash of the Flutter repository.
   Future<String> _getCurrentCommit() async {
     if (!_flutterRoot.existsSync()) {
-      throw Exception('Flutter root could not be found: $_flutterRoot\n');
+      throw SkiaException('Flutter root could not be found: $_flutterRoot\n');
     } else {
       final io.ProcessResult revParse = await process.run(
         <String>['git', 'rev-parse', 'HEAD'],
         workingDirectory: _flutterRoot.path,
       );
       if (revParse.exitCode != 0) {
-        throw Exception('Current commit of Flutter can not be found.');
+        throw const SkiaException('Current commit of Flutter can not be found.');
       }
       return (revParse.stdout as String/*!*/).trim();
     }