Merge github.com:grpc/grpc into fuzzing-memory

12 files changed, 326 insertions, 25 deletions

diff --git a/test/core/client_channel/lb_policies_test.c b/test/core/client_channel/lb_policies_test.c
index efa4ad7ee6..057b90ec84 100644
--- a/test/core/client_channel/lb_policies_test.c
+++ b/test/core/client_channel/lb_policies_test.c
@@ -517,7 +517,7 @@ static grpc_channel *create_client(const servers_fixture *f) {
   grpc_channel *client;
   char *client_hostport;
   char *servers_hostports_str;
-  grpc_arg arg_array[2];
+  grpc_arg arg_array[3];
   grpc_channel_args args;
 
   servers_hostports_str = gpr_strjoin_sep((const char **)f->servers_hostports,
@@ -530,7 +530,10 @@ static grpc_channel *create_client(const servers_fixture *f) {
   arg_array[1].type = GRPC_ARG_STRING;
   arg_array[1].key = GRPC_ARG_LB_POLICY_NAME;
   arg_array[1].value.string = "ROUND_ROBIN";
-  args.num_args = 2;
+  arg_array[2].type = GRPC_ARG_INTEGER;
+  arg_array[2].key = GRPC_ARG_HTTP2_MIN_TIME_BETWEEN_PINGS_MS;
+  arg_array[2].value.integer = 0;
+  args.num_args = GPR_ARRAY_SIZE(arg_array);
   args.args = arg_array;
 
   client = grpc_insecure_channel_create(client_hostport, &args, NULL);
diff --git a/test/core/end2end/bad_server_response_test.c b/test/core/end2end/bad_server_response_test.c
index d5f428eb82..42d960c428 100644
--- a/test/core/end2end/bad_server_response_test.c
+++ b/test/core/end2end/bad_server_response_test.c
@@ -135,7 +135,7 @@ static void handle_read(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
 
   gpr_log(GPR_DEBUG, "got %" PRIuPTR " bytes, expected %" PRIuPTR " bytes",
           state.incoming_data_length, EXPECTED_INCOMING_DATA_LENGTH);
-  if (state.incoming_data_length > EXPECTED_INCOMING_DATA_LENGTH) {
+  if (state.incoming_data_length >= EXPECTED_INCOMING_DATA_LENGTH) {
     handle_write(exec_ctx);
   } else {
     grpc_endpoint_read(exec_ctx, state.tcp, &state.temp_incoming_buffer,
diff --git a/test/core/end2end/end2end_nosec_tests.c b/test/core/end2end/end2end_nosec_tests.c
index b162bf2f40..fdfa31b5fb 100644
--- a/test/core/end2end/end2end_nosec_tests.c
+++ b/test/core/end2end/end2end_nosec_tests.c
@@ -41,6 +41,8 @@
 
 #include <grpc/support/log.h>
 
+#include "test/core/util/debugger_macros.h"
+
 static bool g_pre_init_called = false;
 
 extern void authority_not_supported(grpc_end2end_test_config config);
@@ -143,6 +145,7 @@ extern void write_buffering_at_end_pre_init(void);
 void grpc_end2end_tests_pre_init(void) {
   GPR_ASSERT(!g_pre_init_called);
   g_pre_init_called = true;
+  grpc_summon_debugger_macros();
   authority_not_supported_pre_init();
   bad_hostname_pre_init();
   binary_metadata_pre_init();
diff --git a/test/core/end2end/end2end_tests.c b/test/core/end2end/end2end_tests.c
index 9bca0c81f6..f529d6a899 100644
--- a/test/core/end2end/end2end_tests.c
+++ b/test/core/end2end/end2end_tests.c
@@ -41,6 +41,8 @@
 
 #include <grpc/support/log.h>
 
+#include "test/core/util/debugger_macros.h"
+
 static bool g_pre_init_called = false;
 
 extern void authority_not_supported(grpc_end2end_test_config config);
@@ -145,6 +147,7 @@ extern void write_buffering_at_end_pre_init(void);
 void grpc_end2end_tests_pre_init(void) {
   GPR_ASSERT(!g_pre_init_called);
   g_pre_init_called = true;
+  grpc_summon_debugger_macros();
   authority_not_supported_pre_init();
   bad_hostname_pre_init();
   binary_metadata_pre_init();
diff --git a/test/core/end2end/tests/ping.c b/test/core/end2end/tests/ping.c
index 61f4337f2f..f5bfac2255 100644
--- a/test/core/end2end/tests/ping.c
+++ b/test/core/end2end/tests/ping.c
@@ -37,6 +37,7 @@
 #include <grpc/support/sync.h>
 #include <grpc/support/thd.h>
 #include <grpc/support/time.h>
+#include <grpc/support/useful.h>
 
 #include "test/core/end2end/cq_verifier.h"
 
@@ -48,7 +49,15 @@ static void test_ping(grpc_end2end_test_config config) {
   grpc_connectivity_state state = GRPC_CHANNEL_IDLE;
   int i;
 
-  config.init_client(&f, NULL);
+  grpc_arg a[] = {{.type = GRPC_ARG_INTEGER,
+                   .key = GRPC_ARG_HTTP2_MIN_TIME_BETWEEN_PINGS_MS,
+                   .value.integer = 0},
+                  {.type = GRPC_ARG_INTEGER,
+                   .key = GRPC_ARG_HTTP2_MAX_PINGS_WITHOUT_DATA,
+                   .value.integer = 20}};
+  grpc_channel_args client_args = {.num_args = GPR_ARRAY_SIZE(a), .args = a};
+
+  config.init_client(&f, &client_args);
   config.init_server(&f, NULL);
 
   grpc_channel_ping(f.client, f.cq, tag(0), NULL);
diff --git a/test/core/end2end/tests/resource_quota_server.c b/test/core/end2end/tests/resource_quota_server.c
index 3fbe0aa0d0..4f9ed7a3a1 100644
--- a/test/core/end2end/tests/resource_quota_server.c
+++ b/test/core/end2end/tests/resource_quota_server.c
@@ -160,6 +160,7 @@ void resource_quota_server(grpc_end2end_test_config config) {
   int pending_server_end_calls = 0;
   int cancelled_calls_on_client = 0;
   int cancelled_calls_on_server = 0;
+  int deadline_exceeded = 0;
 
   grpc_byte_buffer *request_payload =
       grpc_raw_byte_buffer_create(&request_payload_slice, 1);
@@ -247,6 +248,9 @@ void resource_quota_server(grpc_end2end_test_config config) {
         case GRPC_STATUS_RESOURCE_EXHAUSTED:
           cancelled_calls_on_client++;
           break;
+        case GRPC_STATUS_DEADLINE_EXCEEDED:
+          deadline_exceeded++;
+          break;
         case GRPC_STATUS_OK:
           break;
         default:
@@ -343,20 +347,19 @@ void resource_quota_server(grpc_end2end_test_config config) {
     }
   }
 
-  gpr_log(
-      GPR_INFO,
-      "Done. %d total calls: %d cancelled at server, %d cancelled at client.",
-      NUM_CALLS, cancelled_calls_on_server, cancelled_calls_on_client);
-
-  /* The call may be cancelled after the server has sent its status but before
-   * the client has received it. This means that we should see strictly more
-   * failures on the client than on the server. */
-  GPR_ASSERT(cancelled_calls_on_client >= cancelled_calls_on_server);
+  gpr_log(GPR_INFO,
+          "Done. %d total calls: %d cancelled at server, %d cancelled at "
+          "client, %d timed out.",
+          NUM_CALLS, cancelled_calls_on_server, cancelled_calls_on_client,
+          deadline_exceeded);
 
   grpc_byte_buffer_destroy(request_payload);
   grpc_slice_unref(request_payload_slice);
   grpc_resource_quota_unref(resource_quota);
 
+  end_test(&f);
+  config.tear_down_data(&f);
+
   free(client_calls);
   free(server_calls);
   free(initial_metadata_recv);
@@ -367,9 +370,6 @@ void resource_quota_server(grpc_end2end_test_config config) {
   free(details);
   free(request_payload_recv);
   free(was_cancelled);
-
-  end_test(&f);
-  config.tear_down_data(&f);
 }
 
 void resource_quota_server_pre_init(void) {}
diff --git a/test/core/transport/bdp_estimator_test.c b/test/core/transport/bdp_estimator_test.c
new file mode 100644
index 0000000000..f55a3ca643
--- /dev/null
+++ b/test/core/transport/bdp_estimator_test.c
@@ -0,0 +1,153 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/transport/bdp_estimator.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/useful.h>
+#include <limits.h>
+#include "src/core/lib/support/string.h"
+#include "test/core/util/test_config.h"
+
+static void test_noop(void) {
+  gpr_log(GPR_INFO, "test_noop");
+  grpc_bdp_estimator est;
+  grpc_bdp_estimator_init(&est, "test");
+}
+
+static void test_get_estimate_no_samples(void) {
+  gpr_log(GPR_INFO, "test_get_estimate_no_samples");
+  grpc_bdp_estimator est;
+  grpc_bdp_estimator_init(&est, "test");
+  int64_t estimate;
+  grpc_bdp_estimator_get_estimate(&est, &estimate);
+}
+
+static void add_samples(grpc_bdp_estimator *estimator, int64_t *samples,
+                        size_t n) {
+  GPR_ASSERT(grpc_bdp_estimator_add_incoming_bytes(estimator, 1234567) == true);
+  grpc_bdp_estimator_schedule_ping(estimator);
+  grpc_bdp_estimator_start_ping(estimator);
+  for (size_t i = 0; i < n; i++) {
+    GPR_ASSERT(grpc_bdp_estimator_add_incoming_bytes(estimator, samples[i]) ==
+               false);
+  }
+  grpc_bdp_estimator_complete_ping(estimator);
+}
+
+static void add_sample(grpc_bdp_estimator *estimator, int64_t sample) {
+  add_samples(estimator, &sample, 1);
+}
+
+static void test_get_estimate_1_sample(void) {
+  gpr_log(GPR_INFO, "test_get_estimate_1_sample");
+  grpc_bdp_estimator est;
+  grpc_bdp_estimator_init(&est, "test");
+  add_sample(&est, 100);
+  int64_t estimate;
+  grpc_bdp_estimator_get_estimate(&est, &estimate);
+}
+
+static void test_get_estimate_2_samples(void) {
+  gpr_log(GPR_INFO, "test_get_estimate_2_samples");
+  grpc_bdp_estimator est;
+  grpc_bdp_estimator_init(&est, "test");
+  add_sample(&est, 100);
+  add_sample(&est, 100);
+  int64_t estimate;
+  grpc_bdp_estimator_get_estimate(&est, &estimate);
+}
+
+static int64_t get_estimate(grpc_bdp_estimator *estimator) {
+  int64_t out;
+  GPR_ASSERT(grpc_bdp_estimator_get_estimate(estimator, &out));
+  return out;
+}
+
+static void test_get_estimate_3_samples(void) {
+  gpr_log(GPR_INFO, "test_get_estimate_3_samples");
+  grpc_bdp_estimator est;
+  grpc_bdp_estimator_init(&est, "test");
+  add_sample(&est, 100);
+  add_sample(&est, 100);
+  add_sample(&est, 100);
+  int64_t estimate;
+  grpc_bdp_estimator_get_estimate(&est, &estimate);
+}
+
+static int64_t next_pow_2(int64_t v) {
+  v--;
+  v |= v >> 1;
+  v |= v >> 2;
+  v |= v >> 4;
+  v |= v >> 8;
+  v |= v >> 16;
+  v |= v >> 32;
+  v++;
+  return v;
+}
+
+static void test_get_estimate_random_values(size_t n) {
+  gpr_log(GPR_INFO, "test_get_estimate_random_values(%" PRIdPTR ")", n);
+  grpc_bdp_estimator est;
+  grpc_bdp_estimator_init(&est, "test");
+  int min = INT_MAX;
+  int max = 65535;  // Windows rand() has limited range, make sure the ASSERT
+                    // passes
+  for (size_t i = 0; i < n; i++) {
+    int sample = rand();
+    if (sample < min) min = sample;
+    if (sample > max) max = sample;
+    add_sample(&est, sample);
+    if (i >= 3) {
+      gpr_log(GPR_DEBUG, "est:%" PRId64 " min:%d max:%d", get_estimate(&est),
+              min, max);
+      GPR_ASSERT(get_estimate(&est) <= 2 * next_pow_2(max));
+    }
+  }
+}
+
+int main(int argc, char **argv) {
+  grpc_test_init(argc, argv);
+  test_noop();
+  test_get_estimate_no_samples();
+  test_get_estimate_1_sample();
+  test_get_estimate_2_samples();
+  test_get_estimate_3_samples();
+  for (size_t i = 3; i < 1000; i = i * 3 / 2) {
+    test_get_estimate_random_values(i);
+  }
+  return 0;
+}
diff --git a/test/core/transport/pid_controller_test.c b/test/core/transport/pid_controller_test.c
index 9614983b00..831343c815 100644
--- a/test/core/transport/pid_controller_test.c
+++ b/test/core/transport/pid_controller_test.c
@@ -33,6 +33,7 @@
 
 #include "src/core/lib/transport/pid_controller.h"
 
+#include <float.h>
 #include <math.h>
 
 #include <grpc/support/alloc.h>
@@ -45,7 +46,14 @@
 static void test_noop(void) {
   gpr_log(GPR_INFO, "test_noop");
   grpc_pid_controller pid;
-  grpc_pid_controller_init(&pid, 1, 1, 1);
+  grpc_pid_controller_init(
+      &pid, (grpc_pid_controller_args){.gain_p = 1,
+                                       .gain_i = 1,
+                                       .gain_d = 1,
+                                       .initial_control_value = 1,
+                                       .min_control_value = DBL_MIN,
+                                       .max_control_value = DBL_MAX,
+                                       .integral_range = DBL_MAX});
 }
 
 static void test_simple_convergence(double gain_p, double gain_i, double gain_d,
@@ -55,16 +63,24 @@ static void test_simple_convergence(double gain_p, double gain_i, double gain_d,
           "start=%lf",
           gain_p, gain_i, gain_d, dt, set_point, start);
   grpc_pid_controller pid;
-  grpc_pid_controller_init(&pid, 0.2, 0.1, 0.1);
+  grpc_pid_controller_init(
+      &pid, (grpc_pid_controller_args){.gain_p = gain_p,
+                                       .gain_i = gain_i,
+                                       .gain_d = gain_d,
+                                       .initial_control_value = start,
+                                       .min_control_value = DBL_MIN,
+                                       .max_control_value = DBL_MAX,
+                                       .integral_range = DBL_MAX});
 
-  double current = start;
-
-  for (int i = 0; i < 1000; i++) {
-    current += grpc_pid_controller_update(&pid, set_point - current, 1);
+  for (int i = 0; i < 100000; i++) {
+    grpc_pid_controller_update(&pid, set_point - grpc_pid_controller_last(&pid),
+                               1);
   }
 
-  GPR_ASSERT(fabs(set_point - current) < 0.1);
-  GPR_ASSERT(fabs(pid.error_integral) < 0.1);
+  GPR_ASSERT(fabs(set_point - grpc_pid_controller_last(&pid)) < 0.1);
+  if (gain_i > 0) {
+    GPR_ASSERT(fabs(pid.error_integral) < 0.1);
+  }
 }
 
 int main(int argc, char **argv) {
diff --git a/test/core/util/BUILD b/test/core/util/BUILD
index 8769683b23..5c90f1db44 100644
--- a/test/core/util/BUILD
+++ b/test/core/util/BUILD
@@ -46,6 +46,7 @@ cc_library(
 cc_library(
     name = "grpc_test_util",
     srcs = [
+        "debugger_macros.c",
         "grpc_profiler.c",
         "mock_endpoint.c",
         "parse_hexstring.c",
@@ -58,6 +59,7 @@ cc_library(
         "test_tcp_server.c",
     ],
     hdrs = [
+        "debugger_macros.h",
         "grpc_profiler.h",
         "mock_endpoint.h",
         "parse_hexstring.h",
diff --git a/test/core/util/debugger_macros.c b/test/core/util/debugger_macros.c
new file mode 100644
index 0000000000..de6a2f38a7
--- /dev/null
+++ b/test/core/util/debugger_macros.c
@@ -0,0 +1,71 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+/*
+ * A collection of 'macros' that help navigating the grpc object hierarchy
+ * Not intended to be robust for main-line code, often cuts across abstraction
+ * boundaries.
+ */
+
+#include <stdio.h>
+
+#include "src/core/ext/client_channel/client_channel.h"
+#include "src/core/ext/transport/chttp2/transport/internal.h"
+#include "src/core/lib/channel/connected_channel.h"
+#include "src/core/lib/surface/call.h"
+
+void grpc_summon_debugger_macros() {}
+
+grpc_stream *grpc_transport_stream_from_call(grpc_call *call) {
+  grpc_call_stack *cs = grpc_call_get_call_stack(call);
+  for (;;) {
+    grpc_call_element *el = grpc_call_stack_element(cs, cs->count - 1);
+    if (el->filter == &grpc_client_channel_filter) {
+      grpc_subchannel_call *scc = grpc_client_channel_get_subchannel_call(el);
+      if (scc == NULL) {
+        fprintf(stderr, "No subchannel-call");
+        return NULL;
+      }
+      cs = grpc_subchannel_call_get_call_stack(scc);
+    } else if (el->filter == &grpc_connected_filter) {
+      return grpc_connected_channel_get_stream(el);
+    } else {
+      fprintf(stderr, "Unrecognized filter: %s", el->filter->name);
+      return NULL;
+    }
+  }
+}
+
+grpc_chttp2_stream *grpc_chttp2_stream_from_call(grpc_call *call) {
+  return (grpc_chttp2_stream *)grpc_transport_stream_from_call(call);
+}
diff --git a/test/core/util/debugger_macros.h b/test/core/util/debugger_macros.h
new file mode 100644
index 0000000000..6369ca6c97
--- /dev/null
+++ b/test/core/util/debugger_macros.h
@@ -0,0 +1,39 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_TEST_CORE_UTIL_DEBUGGER_MACROS_H
+#define GRPC_TEST_CORE_UTIL_DEBUGGER_MACROS_H
+
+void grpc_summon_debugger_macros();
+
+#endif /* GRPC_TEST_CORE_UTIL_DEBUGGER_MACROS_H */
diff --git a/test/core/util/passthru_endpoint.c b/test/core/util/passthru_endpoint.c
index 4ff93005d7..1e82c737c6 100644
--- a/test/core/util/passthru_endpoint.c
+++ b/test/core/util/passthru_endpoint.c
@@ -152,7 +152,9 @@ static void me_destroy(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep) {
 }
 
 static char *me_get_peer(grpc_endpoint *ep) {
-  return gpr_strdup("fake:mock_endpoint");
+  passthru_endpoint *p = ((half *)ep)->parent;
+  return ((half *)ep) == &p->client ? gpr_strdup("fake:mock_client_endpoint")
+                                    : gpr_strdup("fake:mock_server_endpoint");
 }
 
 static int me_get_fd(grpc_endpoint *ep) { return -1; }