Fix runners array quirk

rules/test.bzl

@@ -1,4 +1,5 @@
 load("@build_bazel_rules_apple//apple/internal/testing:ios_rules.bzl", _ios_internal_ui_test_bundle = "ios_internal_ui_test_bundle", _ios_internal_unit_test_bundle = "ios_internal_unit_test_bundle", _ios_ui_test = "ios_ui_test", _ios_unit_test = "ios_unit_test")
+load("@bazel_skylib//lib:types.bzl", "types")
 load("//rules:library.bzl", "apple_library")
 load("//rules:plists.bzl", "process_infoplists")
 load("//rules/internal:framework_middleman.bzl", "dep_middleman", "framework_middleman")
@@ -162,13 +163,16 @@ def _ios_test(name, bundle_rule, test_rule, test_factory, apple_library, infopli
         ios_test_kwargs["test_host"] = "@build_bazel_rules_ios//rules/test_host_app:iOS-%s-AppHost" % ios_test_kwargs.get("minimum_os_version")
 
     runners = kwargs.pop("runners", None)
+    runner = kwargs.pop("runner", _DEFAULT_APPLE_TEST_RUNNER)
     if "runner" in kwargs and (runners and runners != []):
         fail("cannot specify both runner and runners for %s" % name)
-
     if runners:
         ios_test_kwargs["runners"] = runners
+    elif types.is_list(runner):
+        # Runners attribute has accepts a list - we need to gen many tests
+        ios_test_kwargs["runners"] = runner
     else:
-        ios_test_kwargs["runner"] = kwargs.pop("runner", _DEFAULT_APPLE_TEST_RUNNER)
+        ios_test_kwargs["runner"] = runner
 
     # Deduplicate against the test deps
     if ios_test_kwargs.get("test_host", None):