diff --git a/rcl/test/rcl/allocator_testing_utils.h b/rcl/test/rcl/allocator_testing_utils.h
new file mode 100644
index 000000000..cdc707d68
--- /dev/null
+++ b/rcl/test/rcl/allocator_testing_utils.h
@@ -0,0 +1,94 @@
+// Copyright 2020 Open Source Robotics Foundation, Inc.
+//
+// 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.
+
+#ifndef RCL__ALLOCATOR_TESTING_UTILS_H_
+#define RCL__ALLOCATOR_TESTING_UTILS_H_
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#include <stddef.h>
+
+#include "rcutils/allocator.h"
+
+typedef struct __failing_allocator_state
+{
+  bool is_failing;
+} __failing_allocator_state;
+
+void *
+failing_malloc(size_t size, void * state)
+{
+  if (((__failing_allocator_state *)state)->is_failing) {
+    return nullptr;
+  }
+  return rcutils_get_default_allocator().allocate(size, rcutils_get_default_allocator().state);
+}
+
+void *
+failing_realloc(void * pointer, size_t size, void * state)
+{
+  if (((__failing_allocator_state *)state)->is_failing) {
+    return nullptr;
+  }
+  return rcutils_get_default_allocator().reallocate(
+    pointer, size, rcutils_get_default_allocator().state);
+}
+
+void
+failing_free(void * pointer, void * state)
+{
+  if (((__failing_allocator_state *)state)->is_failing) {
+    return;
+  }
+  rcutils_get_default_allocator().deallocate(pointer, rcutils_get_default_allocator().state);
+}
+
+void *
+failing_calloc(size_t number_of_elements, size_t size_of_element, void * state)
+{
+  if (((__failing_allocator_state *)state)->is_failing) {
+    return nullptr;
+  }
+  return rcutils_get_default_allocator().zero_allocate(
+    number_of_elements, size_of_element, rcutils_get_default_allocator().state);
+}
+
+static inline rcutils_allocator_t
+get_failing_allocator(void)
+{
+  static __failing_allocator_state state;
+  state.is_failing = true;
+  auto failing_allocator = rcutils_get_default_allocator();
+  failing_allocator.allocate = failing_malloc;
+  failing_allocator.deallocate = failing_free;
+  failing_allocator.reallocate = failing_realloc;
+  failing_allocator.zero_allocate = failing_calloc;
+  failing_allocator.state = &state;
+  return failing_allocator;
+}
+
+static inline void
+set_failing_allocator_is_failing(rcutils_allocator_t & failing_allocator, bool state)
+{
+  ((__failing_allocator_state *)failing_allocator.state)->is_failing = state;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // RCL__ALLOCATOR_TESTING_UTILS_H_
diff --git a/rcl/test/rcl/test_time.cpp b/rcl/test/rcl/test_time.cpp
index 2b552ea68..f267f0871 100644
--- a/rcl/test/rcl/test_time.cpp
+++ b/rcl/test/rcl/test_time.cpp
@@ -268,6 +268,18 @@ TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), specific_clock_instantiation) {
     EXPECT_EQ(uninitialized_clock.type, RCL_CLOCK_UNINITIALIZED) <<
       "Expected time source of type RCL_CLOCK_UNINITIALIZED";
     EXPECT_TRUE(rcutils_allocator_is_valid(&(uninitialized_clock.allocator)));
+    ret = rcl_clock_fini(&uninitialized_clock);
+    EXPECT_EQ(ret, RCL_RET_INVALID_ARGUMENT) << rcl_get_error_string().str;
+    rcl_reset_error();
+    EXPECT_EQ(
+      rcl_ros_clock_fini(&uninitialized_clock), RCL_RET_ERROR) << rcl_get_error_string().str;
+    rcl_reset_error();
+    EXPECT_EQ(
+      rcl_steady_clock_fini(&uninitialized_clock), RCL_RET_ERROR) << rcl_get_error_string().str;
+    rcl_reset_error();
+    EXPECT_EQ(
+      rcl_system_clock_fini(&uninitialized_clock), RCL_RET_ERROR) << rcl_get_error_string().str;
+    rcl_reset_error();
   }
   {
     rcl_clock_t ros_clock;
@@ -296,6 +308,12 @@ TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), specific_clock_instantiation) {
     ret = rcl_clock_fini(&steady_clock);
     EXPECT_EQ(ret, RCL_RET_OK) << rcl_get_error_string().str;
   }
+  {
+    rcl_clock_t fail_clock;
+    rcl_clock_type_t undefined_type = (rcl_clock_type_t) 130;
+    rcl_ret_t ret = rcl_clock_init(undefined_type, &fail_clock, &allocator);
+    EXPECT_EQ(ret, RCL_RET_INVALID_ARGUMENT) << rcl_get_error_string().str;
+  }
 }
 
 TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), rcl_time_difference) {
@@ -333,6 +351,9 @@ TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), rcl_time_difference) {
   ret = rcl_difference_times(&b, &a, &d);
   EXPECT_EQ(ret, RCL_RET_OK) << rcl_get_error_string().str;
   EXPECT_EQ(d.nanoseconds, -1000);
+
+  b.clock_type = RCL_SYSTEM_TIME;
+  EXPECT_EQ(rcl_difference_times(&a, &b, &d), RCL_RET_ERROR) << rcl_get_error_string().str;
 }
 
 TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), rcl_time_difference_signed) {
@@ -484,6 +505,33 @@ TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), rcl_time_clock_change_callbacks) {
   reset_callback_triggers();
 }
 
+TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), rcl_time_fail_set_jump_callbacks) {
+  rcl_allocator_t allocator = rcl_get_default_allocator();
+  rcl_clock_t fail_clock;
+  rcl_time_jump_t time_jump;
+  rcl_jump_threshold_t threshold;
+  rcl_ret_t ret = rcl_clock_init(RCL_CLOCK_UNINITIALIZED, &fail_clock, &allocator);
+  EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+
+  threshold.on_clock_change = false;
+  threshold.min_forward.nanoseconds = -1;
+  threshold.min_backward.nanoseconds = 0;
+
+  EXPECT_EQ(
+    RCL_RET_INVALID_ARGUMENT,
+    rcl_clock_add_jump_callback(&fail_clock, threshold, clock_callback, &time_jump)) <<
+    rcl_get_error_string().str;
+  rcl_reset_error();
+
+  threshold.min_forward.nanoseconds = 0;
+  threshold.min_backward.nanoseconds = 1;
+  EXPECT_EQ(
+    RCL_RET_INVALID_ARGUMENT,
+    rcl_clock_add_jump_callback(&fail_clock, threshold, clock_callback, &time_jump)) <<
+    rcl_get_error_string().str;
+  rcl_reset_error();
+}
+
 TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), rcl_time_forward_jump_callbacks) {
   rcl_allocator_t allocator = rcl_get_default_allocator();
   auto * ros_clock =
@@ -730,3 +778,29 @@ TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), add_remove_add_jump_callback) {
     rcl_get_error_string().str;
   EXPECT_EQ(1u, clock->num_jump_callbacks);
 }
+
+TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), failed_get_now) {
+  rcl_allocator_t allocator = rcl_get_default_allocator();
+  rcl_clock_t uninitialized_clock;
+  rcl_time_point_value_t query_now;
+  rcl_ret_t ret = rcl_clock_init(RCL_CLOCK_UNINITIALIZED, &uninitialized_clock, &allocator);
+  EXPECT_EQ(ret, RCL_RET_OK) << rcl_get_error_string().str;
+  EXPECT_EQ(uninitialized_clock.type, RCL_CLOCK_UNINITIALIZED);
+  uninitialized_clock.get_now = NULL;
+  EXPECT_EQ(RCL_RET_ERROR, rcl_clock_get_now(&uninitialized_clock, &query_now));
+}
+
+TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), fail_override) {
+  rcl_clock_t ros_clock;
+  rcl_allocator_t allocator = rcl_get_default_allocator();
+  bool result;
+  rcl_time_point_value_t set_point = 1000000000ull;
+  ASSERT_EQ(
+    RCL_RET_OK, rcl_clock_init(
+      RCL_CLOCK_UNINITIALIZED, &ros_clock, &allocator)) << rcl_get_error_string().str;
+
+  EXPECT_EQ(RCL_RET_ERROR, rcl_enable_ros_time_override(&ros_clock));
+  EXPECT_EQ(RCL_RET_ERROR, rcl_disable_ros_time_override(&ros_clock));
+  EXPECT_EQ(RCL_RET_ERROR, rcl_is_enabled_ros_time_override(&ros_clock, &result));
+  EXPECT_EQ(RCL_RET_ERROR, rcl_set_ros_time_override(&ros_clock, set_point));
+}
diff --git a/rcl/test/rcl/test_timer.cpp b/rcl/test/rcl/test_timer.cpp
index 746f575b6..07edd5c97 100644
--- a/rcl/test/rcl/test_timer.cpp
+++ b/rcl/test/rcl/test_timer.cpp
@@ -23,6 +23,8 @@
 #include "osrf_testing_tools_cpp/scope_exit.hpp"
 #include "rcl/error_handling.h"
 
+#include "./allocator_testing_utils.h"
+
 class TestTimerFixture : public ::testing::Test
 {
 public:
@@ -72,6 +74,12 @@ static void callback_function(rcl_timer_t * timer, int64_t last_call)
   (void) last_call;
   times_called++;
 }
+static void callback_function_changed(rcl_timer_t * timer, int64_t last_call)
+{
+  (void) timer;
+  (void) last_call;
+  times_called--;
+}
 
 class TestPreInitTimer : public TestTimerFixture
 {
@@ -80,6 +88,7 @@ class TestPreInitTimer : public TestTimerFixture
   rcl_allocator_t allocator;
   rcl_timer_t timer;
   rcl_timer_callback_t timer_callback_test = &callback_function;
+  rcl_timer_callback_t timer_callback_changed = &callback_function_changed;
 
   void SetUp() override
   {
@@ -559,3 +568,115 @@ TEST_F(TestPreInitTimer, test_timer_get_allocator) {
 
   EXPECT_EQ(NULL, rcl_timer_get_allocator(nullptr));
 }
+
+TEST_F(TestPreInitTimer, test_timer_clock) {
+  rcl_clock_t * clock_impl = nullptr;
+  EXPECT_EQ(RCL_RET_OK, rcl_timer_clock(&timer, &clock_impl)) << rcl_get_error_string().str;
+  EXPECT_EQ(clock_impl, &clock);
+}
+
+TEST_F(TestPreInitTimer, test_timer_call) {
+  int64_t next_call_start = 0;
+  int64_t next_call_end = 0;
+  int64_t old_period = 0;
+  times_called = 0;
+
+  EXPECT_EQ(RCL_RET_OK, rcl_timer_get_time_until_next_call(&timer, &next_call_start));
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_call(&timer)) << rcl_get_error_string().str;
+  EXPECT_EQ(times_called, 1);
+
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_call(&timer)) << rcl_get_error_string().str;
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_call(&timer)) << rcl_get_error_string().str;
+  EXPECT_EQ(times_called, 3);
+  EXPECT_EQ(RCL_RET_OK, rcl_timer_get_time_until_next_call(&timer, &next_call_end));
+  EXPECT_GT(next_call_end, next_call_start);
+
+  next_call_start = next_call_end;
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_exchange_period(&timer, 0, &old_period));
+  EXPECT_EQ(RCL_S_TO_NS(1), old_period);
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_call(&timer)) << rcl_get_error_string().str;
+  EXPECT_EQ(times_called, 4);
+  EXPECT_EQ(RCL_RET_OK, rcl_timer_get_time_until_next_call(&timer, &next_call_end));
+  EXPECT_GT(next_call_start, next_call_end);
+
+  EXPECT_EQ(RCL_RET_OK, rcl_timer_cancel(&timer)) << rcl_get_error_string().str;
+  EXPECT_EQ(RCL_RET_TIMER_CANCELED, rcl_timer_call(&timer));
+  EXPECT_EQ(times_called, 4);
+}
+
+TEST_F(TestPreInitTimer, test_get_callback) {
+  ASSERT_EQ(timer_callback_test, rcl_timer_get_callback(&timer)) << rcl_get_error_string().str;
+}
+
+TEST_F(TestPreInitTimer, test_timer_reset) {
+  int64_t next_call_start = 0;
+  int64_t next_call_end = 0;
+  times_called = 0;
+
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_call(&timer)) << rcl_get_error_string().str;
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_call(&timer)) << rcl_get_error_string().str;
+  EXPECT_EQ(times_called, 2);
+  EXPECT_EQ(RCL_RET_OK, rcl_timer_get_time_until_next_call(&timer, &next_call_start));
+
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_reset(&timer));
+  EXPECT_EQ(RCL_RET_OK, rcl_timer_get_time_until_next_call(&timer, &next_call_end));
+  EXPECT_GT(next_call_start, next_call_end);
+
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_cancel(&timer)) << rcl_get_error_string().str;
+  EXPECT_EQ(RCL_RET_TIMER_CANCELED, rcl_timer_call(&timer));
+  EXPECT_EQ(times_called, 2);
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_reset(&timer));
+  EXPECT_EQ(RCL_RET_OK, rcl_timer_call(&timer)) << rcl_get_error_string().str;
+  EXPECT_EQ(times_called, 3);
+}
+
+TEST_F(TestPreInitTimer, test_timer_exchange_callback) {
+  times_called = 0;
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_call(&timer)) << rcl_get_error_string().str;
+  EXPECT_EQ(times_called, 1);
+  ASSERT_EQ(
+    timer_callback_test, rcl_timer_exchange_callback(
+      &timer, timer_callback_changed)) << rcl_get_error_string().str;
+
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_call(&timer)) << rcl_get_error_string().str;
+  EXPECT_EQ(times_called, 0);
+}
+
+TEST_F(TestPreInitTimer, test_invalid_get_guard) {
+  ASSERT_EQ(NULL, rcl_timer_get_guard_condition(nullptr));
+}
+
+TEST_F(TestPreInitTimer, test_invalid_init_fini) {
+  rcl_allocator_t bad_allocator = get_failing_allocator();
+  rcl_timer_t timer_fail = rcl_get_zero_initialized_timer();
+
+  EXPECT_EQ(
+    RCL_RET_ALREADY_INIT, rcl_timer_init(
+      &timer, &clock, this->context_ptr, 500, nullptr,
+      rcl_get_default_allocator())) << rcl_get_error_string().str;
+
+  ASSERT_EQ(
+    RCL_RET_BAD_ALLOC, rcl_timer_init(
+      &timer_fail, &clock, this->context_ptr, RCL_S_TO_NS(1), timer_callback_test,
+      bad_allocator)) << rcl_get_error_string().str;
+
+  EXPECT_EQ(RCL_RET_OK, rcl_timer_fini(nullptr));
+}
+
+TEST_F(TestPreInitTimer, test_timer_get_period) {
+  int64_t period = 0;
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_get_period(&timer, &period));
+  EXPECT_EQ(RCL_S_TO_NS(1), period);
+
+  EXPECT_EQ(RCL_RET_INVALID_ARGUMENT, rcl_timer_get_period(nullptr, &period));
+  EXPECT_EQ(RCL_RET_INVALID_ARGUMENT, rcl_timer_get_period(&timer, nullptr));
+}
+
+TEST_F(TestPreInitTimer, test_time_since_last_call) {
+  rcl_time_point_value_t time_sice_next_call_start = 0u;
+  rcl_time_point_value_t time_sice_next_call_end = 0u;
+
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_get_time_since_last_call(&timer, &time_sice_next_call_start));
+  ASSERT_EQ(RCL_RET_OK, rcl_timer_get_time_since_last_call(&timer, &time_sice_next_call_end));
+  EXPECT_GT(time_sice_next_call_end, time_sice_next_call_start);
+}