Make sure ios tests fail if they fail (flutter/engine#20518)

* Make sure ios tests fail if they fail

* explain

engine/src/flutter/testing/ios/IosUnitTests/run_tests.sh

@@ -8,9 +8,6 @@ if [ $# -eq 1 ]; then
   FLUTTER_ENGINE=$1
 fi
 
-set -o pipefail && xcodebuild -sdk iphonesimulator \
-  -scheme IosUnitTests \
-  -destination 'platform=iOS Simulator,name=iPhone 8' \
-  test \
-  FLUTTER_ENGINE=$FLUTTER_ENGINE
+../../run_tests.py --variant $FLUTTER_ENGINE --type objc --ios-variant $FLUTTER_ENGINE
+
 popd

engine/src/flutter/testing/run_tests.py

@@ -370,17 +370,19 @@ def RunObjcTests(ios_variant='ios_debug_sim_unopt'):
   ios_out_dir = os.path.join(out_dir, ios_variant)
   EnsureIosTestsAreBuilt(ios_out_dir)
 
-  pretty = "cat" if subprocess.call(["which", "xcpretty"]) else "xcpretty"
   ios_unit_test_dir = os.path.join(buildroot_dir, 'flutter', 'testing', 'ios', 'IosUnitTests')
 
+  # Avoid using xcpretty unless the following can be addressed:
+  # - Make sure all relevant failure output is printed on a failure.
+  # - Make sure that a failing exit code is set for CI.
+  # See https://github.com/flutter/flutter/issues/63742
   command = [
     'xcodebuild '
     '-sdk iphonesimulator '
     '-scheme IosUnitTests '
     "-destination platform='iOS Simulator,name=iPhone 8' "
     'test '
-    'FLUTTER_ENGINE=' + ios_variant +
-    ' | ' + pretty
+    'FLUTTER_ENGINE=' + ios_variant
   ]
   RunCmd(command, cwd=ios_unit_test_dir, shell=True)