Large flutter test suite can fail with "Failed to load: Too many open files" #34612

$ cd packages/flutter
$ flutter test

00:57 +1113 ~25: flutter/packages/flutter/test/cupertino/scaffold_test.dart: Contents have automatic sliver padding between translucent bars                                    [  +18 ms] test 175: error caught during test; sending to test framework
[   +3 ms] test 175: cleaning up...
[        ] test 175: deleting temporary directory
[   +3 ms] test 175: shutting down test harness socket server
00:57 +1113 ~25 -1: loading flutter/packages/flutter/test/cupertino/action_sheet_test.dart [E]                                                                                  
  Failed to load "flutter/packages/flutter/test/cupertino/action_sheet_test.dart":
  Too many open files
    Command: flutter/bin/cache/artifacts/engine/darwin-x64/flutter_tester --disable-observatory --enable-checked-mode --verify-entry-points --enable-software-rendering --skia-deterministic-rendering --enable-dart-profiling --non-interactive --use-test-fonts --packages=flutter/packages/flutter/.packages /var/folders/mv/qlhc4vsj6tqct166rw3zwmth00mfq2/T/flutter_test_listener.Q2tyNY/listener.dart.dill

$ ulimit -n
256

$ flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel unknown, v1.7.5-pre.17, on Mac OS X 10.14.5 18F203, locale en-US)
 
[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
[✓] Xcode - develop for iOS and macOS (Xcode 10.2.1)
[✓] iOS tools - develop for iOS devices
[✓] Android Studio (version 3.4)
[✓] VS Code (version 1.35.0)
[✓] Connected device (1 available)

• No issues found!