[flutter_tools] add more debugging when pub get fails (#108062)

packages/flutter_tools/lib/src/dart/pub.dart

@@ -266,17 +266,10 @@ class _DefaultPub implements Pub {
     } catch (exception) { // ignore: avoid_catches_without_on_clauses
       status?.cancel();
       if (exception is io.ProcessException) {
-        final StringBuffer buffer = StringBuffer(exception.message);
+        final StringBuffer buffer = StringBuffer('${exception.message}\n');
         buffer.writeln('Working directory: "$directory"');
         final Map<String, String> env = await _createPubEnvironment(context, flutterRootOverride);
-        if (env.entries.isNotEmpty) {
-          buffer.writeln('pub env: {');
-          for (final MapEntry<String, String> entry in env.entries) {
-            buffer.writeln('  "${entry.key}": "${entry.value}",');
-          }
-          buffer.writeln('}');
-        }
-
+        buffer.write(_stringifyPubEnv(env));
         throw io.ProcessException(
           exception.executable,
           exception.arguments,
@@ -298,6 +291,20 @@ class _DefaultPub implements Pub {
     );
   }
 
+  // For surfacing pub env in crash reporting
+  String _stringifyPubEnv(Map<String, String> map, {String prefix = 'pub env'}) {
+    if (map.isEmpty) {
+      return '';
+    }
+    final StringBuffer buffer = StringBuffer();
+    buffer.writeln('$prefix: {');
+    for (final MapEntry<String, String> entry in map.entries) {
+      buffer.writeln('  "${entry.key}": "${entry.value}",');
+    }
+    buffer.writeln('}');
+    return buffer.toString();
+  }
+
   @override
   Future<void> batch(
     List<String> arguments, {
@@ -330,13 +337,15 @@ class _DefaultPub implements Pub {
     int attempts = 0;
     int duration = 1;
     int code;
+    final List<String> pubCommand = _pubCommand(arguments);
+    final Map<String, String> pubEnvironment = await _createPubEnvironment(context, flutterRootOverride);
     while (true) {
       attempts += 1;
       code = await _processUtils.stream(
-        _pubCommand(arguments),
+        pubCommand,
         workingDirectory: directory,
         mapFunction: filterWrapper, // may set versionSolvingFailed, lastPubMessage
-        environment: await _createPubEnvironment(context, flutterRootOverride),
+        environment: pubEnvironment,
       );
       String? message;
       if (retry) {
@@ -372,7 +381,15 @@ class _DefaultPub implements Pub {
     ).send();
 
     if (code != 0) {
-      throwToolExit('$failureMessage ($code; $lastPubMessage)', exitCode: code);
+      final StringBuffer buffer = StringBuffer('$failureMessage\n');
+      buffer.writeln('command: "${pubCommand.join(' ')}"');
+      buffer.write(_stringifyPubEnv(pubEnvironment));
+      buffer.writeln('exit code: $code');
+      buffer.writeln('last line of pub output: "${lastPubMessage.trim()}"');
+      throwToolExit(
+        buffer.toString(),
+        exitCode: code,
+      );
     }
   }
 

packages/flutter_tools/test/general.shard/dart/pub_get_test.dart

@@ -611,7 +611,7 @@ void main() {
       );
     });
     expect(logger.errorText, isEmpty);
-    expect(error, 'test failed unexpectedly: Exception: pub get failed (69; no message)');
+    expect(error, contains('test failed unexpectedly: Exception: pub get failed'));
     expect(processManager, hasNoRemainingExpectations);
   });
 
@@ -643,9 +643,19 @@ void main() {
       botDetector: const BotDetectorAlwaysNo(),
       processManager: processManager,
     );
+    const String toolExitMessage = '''
+pub get failed
+command: "bin/cache/dart-sdk/bin/dart __deprecated_pub --verbosity=warning get --no-precompile"
+pub env: {
+  "FLUTTER_ROOT": "",
+  "PUB_ENVIRONMENT": "flutter_cli:flutter_tests",
+}
+exit code: 66
+last line of pub output: "err3"
+''';
     await expectLater(
       () => pub.get(context: PubContext.flutterTests),
-      throwsA(isA<ToolExit>().having((ToolExit error) => error.message, 'message', 'pub get failed (66; err3)')),
+      throwsA(isA<ToolExit>().having((ToolExit error) => error.message, 'message', toolExitMessage)),
     );
     expect(logger.statusText,
       'Running "flutter pub get" in /...\n'