Making test/core/iomgr visible.
diff --git a/test/core/iomgr/BUILD b/test/core/iomgr/BUILD
index e2ca3d6..0687fed 100644
--- a/test/core/iomgr/BUILD
+++ b/test/core/iomgr/BUILD
@@ -33,6 +33,8 @@
 
 load("//test/core/util:grpc_fuzzer.bzl", "grpc_fuzzer")
 
+package(default_visibility = ["//visibility:public"]) # Useful for third party devs to test their io manager implementation.
+
 grpc_cc_library(
     name = "endpoint_tests",
     srcs = ["endpoint_tests.c"],