Better bazel C++ iOS tests (with structured test results) (grpc#29354)

* introduce bazelrc for tests with resultstore-uploaded results

* modernize bazel cpp ios tests

* simplify bazel invocation in bazel_cpp_ios_tests

* remove unused bazel core ios tests

tools/internal_ci/macos/grpc_bazel_cpp_ios_tests.cfg

@@ -17,3 +17,24 @@
 # Location of the continuous shell script in repository.
 build_file: "grpc/tools/internal_ci/macos/grpc_run_bazel_cpp_ios_tests.sh"
 
+gfile_resources: "/bigstore/grpc-testing-secrets/gcp_credentials/GrpcTesting-d0eeee2db331.json"
+gfile_resources: "/bigstore/grpc-testing-secrets/gcp_credentials/resultstore_api_key"
+
+bazel_setting {
+  # In order for Kokoro to recognize this as a bazel build and publish the bazel resultstore link,
+  # the bazel_setting section needs to be present and "upsalite_frontend_address" needs to be
+  # set. The rest of configuration from bazel_setting is unused (we configure everything when bazel
+  # command is invoked).
+  upsalite_frontend_address: "https://source.cloud.google.com"
+}
+
+env_vars {
+  # flags will be passed to bazel invocation
+  key: "BAZEL_FLAGS"
+  value: "--cache_test_results=no"
+}
+
+env_vars {
+  key: "UPLOAD_TEST_RESULTS"
+  value: "true"
+}

tools/internal_ci/macos/grpc_run_bazel_cpp_ios_tests.sh

@@ -21,14 +21,25 @@ source $(dirname $0)/../../../tools/internal_ci/helper_scripts/move_src_tree_and
 # change to grpc repo root
 cd $(dirname $0)/../../..
 
+source tools/internal_ci/helper_scripts/prepare_build_macos_rc
+
+# make sure bazel is available
+tools/bazel version
+
 ./tools/run_tests/start_port_server.py
 
-dirs=(end2end server client common codegen util grpclb test)
-for dir in ${dirs[*]}; do
-  echo $dir
-  out=`tools/bazel query "kind(ios_unit_test, tests(//test/cpp/$dir/...))" 2>/dev/null | grep '^//'`
-  for test in $out; do
-    echo "Running: $test"
-    tools/bazel test --test_summary=detailed --test_output=all $test
-  done
-done
+# only select ObjC test from the following subdirs
+# TODO(jtattermusch): start running selected tests from //test/core too.
+test_pattern="//test/cpp/end2end/... + //test/cpp/server/... + //test/cpp/client/... + //test/cpp/common/... + //test/cpp/codegen/... + //test/cpp/util/... + //test/cpp/grpclb/... + //test/cpp/test/..."
+
+# iOS tests are marked as "manual" to prevent them from running by default. To run them, we need to use "bazel query" to list them first.
+ios_tests=$(tools/bazel query "kind(ios_unit_test, tests($test_pattern))" | grep '^//')
+
+python3 tools/run_tests/python_utils/bazel_report_helper.py --report_path bazel_cpp_ios_tests
+
+bazel_cpp_ios_tests/bazel_wrapper \
+  --bazelrc=tools/remote_build/include/test_locally_with_resultstore_results.bazelrc \
+  test \
+  --google_credentials="${KOKORO_GFILE_DIR}/GrpcTesting-d0eeee2db331.json" \
+  $BAZEL_FLAGS \
+  -- ${ios_tests}

tools/remote_build/include/test_locally_with_resultstore_results.bazelrc

@@ -0,0 +1,15 @@
+# Run tests locally, but configure bazel to upload
+# the results to resultstore UI.
+# Also easily extended to use remote cache for
+# locally run builds and tests (but not on by default for safety)
+
+import %workspace%/tools/remote_build/include/rbe_base_config.bazelrc
+
+# Disable uploading to build cache by default. This is to prevent
+# polluting the build cache with local build and test results.
+# When running on CI, we will override this setting along
+# with cache silo keys that prevent the build from being broken
+# by unintentional cache hits.
+build --remote_upload_local_results=false
+
+import %workspace%/tools/remote_build/include/test_config_common.bazelrc