4 files changed, 128 insertions, 6 deletions
diff --git a/test/core/channel/channel_trace_test.cc b/test/core/channel/channel_trace_test.cc
index 99d9a4847f..f224457a55 100644
--- a/test/core/channel/channel_trace_test.cc
+++ b/test/core/channel/channel_trace_test.cc
@@ -187,8 +187,8 @@ TEST_P(ChannelTracerTest, ComplexTest) {
   AddSimpleTrace(&tracer);
   AddSimpleTrace(&tracer);
   AddSimpleTrace(&tracer);
-  sc1.reset(nullptr);
-  sc2.reset(nullptr);
+  sc1.reset();
+  sc2.reset();
 }
 
 // Test a case in which the parent channel has subchannels and the subchannels
@@ -234,9 +234,9 @@ TEST_P(ChannelTracerTest, TestNesting) {
       grpc_slice_from_static_string("subchannel one inactive"), sc1);
   AddSimpleTrace(&tracer);
   ValidateChannelTrace(&tracer, 8, GetParam());
-  sc1.reset(nullptr);
-  sc2.reset(nullptr);
-  conn1.reset(nullptr);
+  sc1.reset();
+  sc2.reset();
+  conn1.reset();
 }
 
 INSTANTIATE_TEST_CASE_P(ChannelTracerTestSweep, ChannelTracerTest,
diff --git a/test/core/gprpp/ref_counted_ptr_test.cc b/test/core/gprpp/ref_counted_ptr_test.cc
index aa30b72282..463b5e8966 100644
--- a/test/core/gprpp/ref_counted_ptr_test.cc
+++ b/test/core/gprpp/ref_counted_ptr_test.cc
@@ -127,7 +127,7 @@ TEST(RefCountedPtr, ResetFromNonNullToNull) {
 TEST(RefCountedPtr, ResetFromNullToNull) {
   RefCountedPtr<Foo> foo;
   EXPECT_EQ(nullptr, foo.get());
-  foo.reset(nullptr);
+  foo.reset();
   EXPECT_EQ(nullptr, foo.get());
 }
 
@@ -175,6 +175,67 @@ TEST(RefCountedPtr, RefCountedWithTracing) {
   foo->Unref(DEBUG_LOCATION, "foo");
 }
 
+class BaseClass : public RefCounted<BaseClass> {
+ public:
+  BaseClass() {}
+};
+
+class Subclass : public BaseClass {
+ public:
+  Subclass() {}
+};
+
+TEST(RefCountedPtr, ConstructFromSubclass) {
+  RefCountedPtr<BaseClass> p(New<Subclass>());
+}
+
+TEST(RefCountedPtr, CopyAssignFromSubclass) {
+  RefCountedPtr<BaseClass> b;
+  EXPECT_EQ(nullptr, b.get());
+  RefCountedPtr<Subclass> s = MakeRefCounted<Subclass>();
+  b = s;
+  EXPECT_NE(nullptr, b.get());
+}
+
+TEST(RefCountedPtr, MoveAssignFromSubclass) {
+  RefCountedPtr<BaseClass> b;
+  EXPECT_EQ(nullptr, b.get());
+  RefCountedPtr<Subclass> s = MakeRefCounted<Subclass>();
+  b = std::move(s);
+  EXPECT_NE(nullptr, b.get());
+}
+
+TEST(RefCountedPtr, ResetFromSubclass) {
+  RefCountedPtr<BaseClass> b;
+  EXPECT_EQ(nullptr, b.get());
+  b.reset(New<Subclass>());
+  EXPECT_NE(nullptr, b.get());
+}
+
+TEST(RefCountedPtr, EqualityWithSubclass) {
+  Subclass* s = New<Subclass>();
+  RefCountedPtr<BaseClass> b(s);
+  EXPECT_EQ(b, s);
+}
+
+void FunctionTakingBaseClass(RefCountedPtr<BaseClass> p) {
+  p.reset();  // To appease clang-tidy.
+}
+
+TEST(RefCountedPtr, CanPassSubclassToFunctionExpectingBaseClass) {
+  RefCountedPtr<Subclass> p = MakeRefCounted<Subclass>();
+  FunctionTakingBaseClass(p);
+}
+
+void FunctionTakingSubclass(RefCountedPtr<Subclass> p) {
+  p.reset();  // To appease clang-tidy.
+}
+
+TEST(RefCountedPtr, CanPassSubclassToFunctionExpectingSubclass) {
+  RefCountedPtr<Subclass> p = MakeRefCounted<Subclass>();
+  FunctionTakingSubclass(p);
+}
+
 }  // namespace
 }  // namespace testing
 }  // namespace grpc_core
diff --git a/test/core/iomgr/BUILD b/test/core/iomgr/BUILD
index fb0490a95f..002671a5fa 100644
--- a/test/core/iomgr/BUILD
+++ b/test/core/iomgr/BUILD
@@ -125,6 +125,19 @@ grpc_cc_test(
 )
 
 grpc_cc_test(
+    name = "grpc_ipv6_loopback_available_test",
+    srcs = ["grpc_ipv6_loopback_available_test.cc"],
+    language = "C++",
+    deps = [
+        "//:gpr",
+        "//:grpc",
+        "//test/core/util:gpr_test_util",
+        "//test/core/util:grpc_test_util",
+    ],
+)
+
+
+grpc_cc_test(
     name = "load_file_test",
     srcs = ["load_file_test.cc"],
     language = "C++",
diff --git a/test/core/iomgr/grpc_ipv6_loopback_available_test.cc b/test/core/iomgr/grpc_ipv6_loopback_available_test.cc
new file mode 100644
index 0000000000..329aa9a851
--- /dev/null
+++ b/test/core/iomgr/grpc_ipv6_loopback_available_test.cc
@@ -0,0 +1,48 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include "src/core/lib/iomgr/port.h"
+
+// grpc_ipv6_loopback_available isn't currently available on UV.
+#ifndef GRPC_UV
+
+#include <grpc/grpc.h>
+#include <grpc/support/log.h>
+#include "test/core/util/test_config.h"
+
+#ifdef GPR_WINDOWS
+#include "src/core/lib/iomgr/socket_windows.h"
+#else
+#include "src/core/lib/iomgr/socket_utils_posix.h"
+#endif
+
+int main(int argc, char** argv) {
+  grpc_test_init(argc, argv);
+  grpc_init();
+  // This test assumes that the ipv6 loopback is available
+  // in all environments in which grpc tests run in.
+  GPR_ASSERT(grpc_ipv6_loopback_available());
+  grpc_shutdown();
+  return 0;
+}
+
+#else
+
+int main(int argc, char** argv) { return 0; }
+
+#endif /* GRPC_UV */