diff --git a/rcl/package.xml b/rcl/package.xml
index 6334f95bb..a28382aff 100644
--- a/rcl/package.xml
+++ b/rcl/package.xml
@@ -25,6 +25,7 @@
   <test_depend>ament_cmake_gtest</test_depend>
   <test_depend>ament_lint_auto</test_depend>
   <test_depend>ament_lint_common</test_depend>
+  <test_depend>mimick_vendor</test_depend>
   <test_depend>rcpputils</test_depend>
   <test_depend>rmw</test_depend>
   <test_depend>rmw_implementation_cmake</test_depend>
diff --git a/rcl/test/CMakeLists.txt b/rcl/test/CMakeLists.txt
index 9e0d85fdd..c177d2ed2 100644
--- a/rcl/test/CMakeLists.txt
+++ b/rcl/test/CMakeLists.txt
@@ -3,6 +3,8 @@ find_package(launch_testing_ament_cmake REQUIRED)
 
 find_package(test_msgs REQUIRED)
 
+find_package(mimick_vendor REQUIRED)
+
 find_package(rcpputils REQUIRED)
 find_package(rcutils REQUIRED)
 find_package(rmw_implementation_cmake REQUIRED)
@@ -207,7 +209,7 @@ function(test_target_function)
     ENV ${rmw_implementation_env_var}
     APPEND_LIBRARY_DIRS ${extra_lib_dirs}
     INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR}/../src/rcl/
-    LIBRARIES ${PROJECT_NAME}
+    LIBRARIES ${PROJECT_NAME} mimick
     AMENT_DEPENDENCIES ${rmw_implementation} "osrf_testing_tools_cpp" "test_msgs"
   )
 
diff --git a/rcl/test/mocking_utils/patch.hpp b/rcl/test/mocking_utils/patch.hpp
new file mode 100644
index 000000000..544dec27a
--- /dev/null
+++ b/rcl/test/mocking_utils/patch.hpp
@@ -0,0 +1,355 @@
+// 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.
+
+// Original file taken from:
+// https://github.com/ros2/rcutils/blob/master/test/mocking_utils/patch.hpp
+
+#ifndef MOCKING_UTILS__PATCH_HPP_
+#define MOCKING_UTILS__PATCH_HPP_
+
+#define MOCKING_UTILS_SUPPORT_VA_LIST
+#if (defined(__aarch64__) || defined(__arm__) || defined(_M_ARM) || defined(__thumb__))
+// In ARM machines, va_list does not define comparison operators
+// nor the compiler allows defining them via operator overloads.
+// Thus, Mimick argument matching code will not compile.
+#undef MOCKING_UTILS_SUPPORT_VA_LIST
+#endif
+
+#ifdef MOCKING_UTILS_SUPPORT_VA_LIST
+#include <cstdarg>
+#endif
+
+#include <functional>
+#include <string>
+#include <type_traits>
+#include <utility>
+
+#include "mimick/mimick.h"
+#include "rcutils/macros.h"
+
+namespace mocking_utils
+{
+
+/// Mimick specific traits for each mocking_utils::Patch instance.
+/**
+ * \tparam ID Numerical identifier of the patch. Ought to be unique.
+ * \tparam SignatureT Type of the symbol to be patched.
+*/
+template<size_t ID, typename SignatureT>
+struct PatchTraits;
+
+/// Traits specialization for ReturnT(void) free functions.
+/**
+ * \tparam ID Numerical identifier of the patch. Ought to be unique.
+ * \tparam ReturnT Return value type.
+ */
+template<size_t ID, typename ReturnT>
+struct PatchTraits<ID, ReturnT(void)>
+{
+  mmk_mock_define(mock_type, ReturnT);
+};
+
+/// Traits specialization for ReturnT(ArgT0) free functions.
+/**
+ * \tparam ID Numerical identifier of the patch. Ought to be unique.
+ * \tparam ReturnT Return value type.
+ * \tparam ArgT0 Argument type.
+ */
+template<size_t ID, typename ReturnT, typename ArgT0>
+struct PatchTraits<ID, ReturnT(ArgT0)>
+{
+  mmk_mock_define(mock_type, ReturnT, ArgT0);
+};
+
+/// Traits specialization for ReturnT(ArgT0, ArgT1) free functions.
+/**
+ * \tparam ID Numerical identifier of the patch. Ought to be unique.
+ * \tparam ReturnT Return value type.
+ * \tparam ArgTx Argument types.
+ */
+template<size_t ID, typename ReturnT,
+  typename ArgT0, typename ArgT1>
+struct PatchTraits<ID, ReturnT(ArgT0, ArgT1)>
+{
+  mmk_mock_define(mock_type, ReturnT, ArgT0, ArgT1);
+};
+
+/// Traits specialization for ReturnT(ArgT0, ArgT1, ArgT2) free functions.
+/**
+ * \tparam ID Numerical identifier of the patch. Ought to be unique.
+ * \tparam ReturnT Return value type.
+ * \tparam ArgTx Argument types.
+ */
+template<size_t ID, typename ReturnT,
+  typename ArgT0, typename ArgT1, typename ArgT2>
+struct PatchTraits<ID, ReturnT(ArgT0, ArgT1, ArgT2)>
+{
+  mmk_mock_define(mock_type, ReturnT, ArgT0, ArgT1, ArgT2);
+};
+
+/// Traits specialization for ReturnT(ArgT0, ArgT1, ArgT2, ArgT3) free functions.
+/**
+ * \tparam ID Numerical identifier of the patch. Ought to be unique.
+ * \tparam ReturnT Return value type.
+ * \tparam ArgTx Argument types.
+ */
+template<size_t ID, typename ReturnT,
+  typename ArgT0, typename ArgT1,
+  typename ArgT2, typename ArgT3>
+struct PatchTraits<ID, ReturnT(ArgT0, ArgT1, ArgT2, ArgT3)>
+{
+  mmk_mock_define(mock_type, ReturnT, ArgT0, ArgT1, ArgT2, ArgT3);
+};
+
+/// Traits specialization for ReturnT(ArgT0, ArgT1, ArgT2, ArgT3, ArgT4)
+/// free functions.
+/**
+ * \tparam ID Numerical identifier of the patch. Ought to be unique.
+ * \tparam ReturnT Return value type.
+ * \tparam ArgTx Argument types.
+ */
+template<size_t ID, typename ReturnT,
+  typename ArgT0, typename ArgT1,
+  typename ArgT2, typename ArgT3, typename ArgT4>
+struct PatchTraits<ID, ReturnT(ArgT0, ArgT1, ArgT2, ArgT3, ArgT4)>
+{
+  mmk_mock_define(mock_type, ReturnT, ArgT0, ArgT1, ArgT2, ArgT3, ArgT4);
+};
+
+/// Traits specialization for ReturnT(ArgT0, ArgT1, ArgT2, ArgT3, ArgT4, ArgT5)
+/// free functions.
+/**
+ * \tparam ID Numerical identifier of the patch. Ought to be unique.
+ * \tparam ReturnT Return value type.
+ * \tparam ArgTx Argument types.
+ */
+template<size_t ID, typename ReturnT,
+  typename ArgT0, typename ArgT1,
+  typename ArgT2, typename ArgT3,
+  typename ArgT4, typename ArgT5>
+struct PatchTraits<ID, ReturnT(ArgT0, ArgT1, ArgT2, ArgT3, ArgT4, ArgT5)>
+{
+  mmk_mock_define(
+    mock_type, ReturnT, ArgT0, ArgT1, ArgT2, ArgT3, ArgT4, ArgT5);
+};
+
+/// Generic trampoline to wrap generalized callables in plain functions.
+/**
+ * \tparam ID Numerical identifier of this trampoline. Ought to be unique.
+ * \tparam SignatureT Type of the symbol this trampoline replaces.
+ */
+template<size_t ID, typename SignatureT>
+struct Trampoline;
+
+/// Trampoline specialization for free functions.
+template<size_t ID, typename ReturnT, typename ... ArgTs>
+struct Trampoline<ID, ReturnT(ArgTs...)>
+{
+  static ReturnT base(ArgTs... args)
+  {
+    return target(std::forward<ArgTs>(args)...);
+  }
+
+  static std::function<ReturnT(ArgTs...)> target;
+};
+
+template<size_t ID, typename ReturnT, typename ... ArgTs>
+std::function<ReturnT(ArgTs...)>
+Trampoline<ID, ReturnT(ArgTs...)>::target;
+
+/// Setup trampoline with the given @p target.
+/**
+ * \param[in] target Callable that this trampoline will target.
+ * \return the plain base function of this trampoline.
+ *
+ * \tparam ID Numerical identifier of this trampoline. Ought to be unique.
+ * \tparam SignatureT Type of the symbol this trampoline replaces.
+ */
+template<size_t ID, typename SignatureT>
+auto prepare_trampoline(std::function<SignatureT> target)
+{
+  Trampoline<ID, SignatureT>::target = target;
+  return Trampoline<ID, SignatureT>::base;
+}
+
+/// Patch class for binary API mocking
+/**
+ * Built on top of Mimick, to enable symbol mocking on a per dynamically
+ * linked binary object basis.
+ *
+ * \tparam ID Numerical identifier for this patch. Ought to be unique.
+ * \tparam SignatureT Type of the symbol to be patched.
+ */
+template<size_t ID, typename SignatureT>
+class Patch;
+
+/// Patch specialization for ReturnT(ArgTs...) free functions.
+/**
+ * \tparam ID Numerical identifier for this patch. Ought to be unique.
+ * \tparam ReturnT Return value type.
+ * \tparam ArgTs Argument types.
+ */
+template<size_t ID, typename ReturnT, typename ... ArgTs>
+class Patch<ID, ReturnT(ArgTs...)>
+{
+public:
+  using mock_type = typename PatchTraits<ID, ReturnT(ArgTs...)>::mock_type;
+
+  /// Construct a patch.
+  /**
+   * \param[in] target Symbol target string, using Mimick syntax
+   *   i.e. "symbol(@scope)?", where scope may be "self" to target the current
+   *   binary, "lib:library_name" to target a given library, "file:path/to/library"
+   *   to target a given file, or "sym:other_symbol" to target the first library
+   *   that defines said symbol.
+   * \param[in] proxy An indirection to call the target function.
+   *   This indirection must ensure this call goes through the function's
+   *   trampoline, as setup by the dynamic linker.
+   * \return a mocking_utils::Patch instance.
+   */
+  explicit Patch(const std::string & target, std::function<ReturnT(ArgTs...)> proxy)
+  : proxy_(proxy)
+  {
+    auto MMK_MANGLE(mock_type, create) =
+      PatchTraits<ID, ReturnT(ArgTs...)>::MMK_MANGLE(mock_type, create);
+    mock_ = mmk_mock(target.c_str(), mock_type);
+  }
+
+  // Copy construction and assignment are disabled.
+  Patch(const Patch &) = delete;
+  Patch & operator=(const Patch &) = delete;
+
+  Patch(Patch && other)
+  {
+    mock_ = other.mock_;
+    other.mock_ = nullptr;
+  }
+
+  Patch & operator=(Patch && other)
+  {
+    if (mock_) {
+      mmk_reset(mock_);
+    }
+    mock_ = other.mock_;
+    other.mock_ = nullptr;
+  }
+
+  ~Patch()
+  {
+    if (mock_) {
+      mmk_reset(mock_);
+    }
+  }
+
+  /// Inject a @p replacement for the patched function.
+  Patch & then_call(std::function<ReturnT(ArgTs...)> replacement) &
+  {
+    auto type_erased_trampoline =
+      reinterpret_cast<mmk_fn>(prepare_trampoline<ID>(replacement));
+    mmk_when(proxy_(any<ArgTs>()...), .then_call = type_erased_trampoline);
+    return *this;
+  }
+
+  /// Inject a @p replacement for the patched function.
+  Patch && then_call(std::function<ReturnT(ArgTs...)> replacement) &&
+  {
+    auto type_erased_trampoline =
+      reinterpret_cast<mmk_fn>(prepare_trampoline<ID>(replacement));
+    mmk_when(proxy_(any<ArgTs>()...), .then_call = type_erased_trampoline);
+    return std::move(*this);
+  }
+
+private:
+  // Helper for template parameter pack expansion using `mmk_any`
+  // macro as pattern.
+  template<typename T>
+  T any() {return mmk_any(T);}
+
+  mock_type mock_;
+  std::function<ReturnT(ArgTs...)> proxy_;
+};
+
+/// Make a patch for a `target` function.
+/**
+ * Useful for type deduction during \ref mocking_utils::Patch construction.
+ *
+ * \param[in] target Symbol target string, using Mimick syntax.
+ * \param[in] proxy An indirection to call the target function.
+ * \return a mocking_utils::Patch instance.
+ *
+ * \tparam ID Numerical identifier for this patch. Ought to be unique.
+ * \tparam SignatureT Type of the function to be patched.
+ *
+ * \sa mocking_utils::Patch for further reference.
+ */
+template<size_t ID, typename SignatureT>
+auto make_patch(const std::string & target, std::function<SignatureT> proxy)
+{
+  return Patch<ID, SignatureT>(target, proxy);
+}
+
+/// Define a dummy operator `op` for a given `type`.
+/**
+ * Useful to enable patching functions that take arguments whose types
+ * do not define basic comparison operators, as required by Mimick.
+*/
+#define MOCKING_UTILS_BOOL_OPERATOR_RETURNS_FALSE(type_, op) \
+  template<typename T> \
+  typename std::enable_if<std::is_same<T, type_>::value, bool>::type \
+  operator op(const T &, const T &) { \
+    return false; \
+  }
+
+/// Get the exact \ref mocking_utils::Patch type for a given `id` and `function`.
+/**
+ * Useful to avoid ignored attribute warnings when using the \b decltype operator.
+ */
+#define MOCKING_UTILS_PATCH_TYPE(id, function) \
+  decltype(mocking_utils::make_patch<id, decltype(function)>("", nullptr))
+
+/// A transparent forwarding proxy to a given `function`.
+/**
+ * Useful to ensure a call to `function` goes through its trampoline.
+ */
+#define MOCKING_UTILS_PATCH_PROXY(function) \
+  [] (auto && ... args)->decltype(auto) { \
+    return function(std::forward<decltype(args)>(args)...); \
+  }
+
+/// Compute a Mimick symbol target string based on which `function` is to be patched
+/// in which `scope`.
+#define MOCKING_UTILS_PATCH_TARGET(scope, function) \
+  (std::string(RCUTILS_STRINGIFY(function)) + "@" + (scope))
+
+/// Patch a `function` with a used-provided `replacement` in a given `scope`.
+#define patch(scope, function, replacement) \
+  make_patch<__COUNTER__, decltype(function)>( \
+    MOCKING_UTILS_PATCH_TARGET(scope, function), MOCKING_UTILS_PATCH_PROXY(function) \
+  ).then_call(replacement)
+
+/// Patch a function with a function that only returns a value
+#define patch_and_return(scope, function, return_value) \
+  patch(scope, function, [&](auto && ...) {return return_value;})
+
+}  // namespace mocking_utils
+
+#ifdef MOCKING_UTILS_SUPPORT_VA_LIST
+// Define dummy comparison operators for C standard va_list type
+MOCKING_UTILS_BOOL_OPERATOR_RETURNS_FALSE(va_list, ==)
+MOCKING_UTILS_BOOL_OPERATOR_RETURNS_FALSE(va_list, !=)
+MOCKING_UTILS_BOOL_OPERATOR_RETURNS_FALSE(va_list, <)
+MOCKING_UTILS_BOOL_OPERATOR_RETURNS_FALSE(va_list, >)
+#endif
+
+#endif  // MOCKING_UTILS__PATCH_HPP_
diff --git a/rcl/test/rcl/test_publisher.cpp b/rcl/test/rcl/test_publisher.cpp
index 40cc36c12..c536f9242 100644
--- a/rcl/test/rcl/test_publisher.cpp
+++ b/rcl/test/rcl/test_publisher.cpp
@@ -21,11 +21,15 @@
 #include "test_msgs/msg/strings.h"
 #include "rosidl_runtime_c/string_functions.h"
 
-#include "./failing_allocator_functions.hpp"
+#include "mimick/mimick.h"
 #include "osrf_testing_tools_cpp/scope_exit.hpp"
 #include "rcl/error_handling.h"
+#include "rmw/validate_full_topic_name.h"
+#include "rmw/validate_node_name.h"
 
+#include "./failing_allocator_functions.hpp"
 #include "./publisher_impl.h"
+#include "../mocking_utils/patch.hpp"
 
 #ifdef RMW_IMPLEMENTATION
 # define CLASSNAME_(NAME, SUFFIX) NAME ## __ ## SUFFIX
@@ -57,7 +61,7 @@ class CLASSNAME (TestPublisherFixture, RMW_IMPLEMENTATION) : public ::testing::T
     }
     this->node_ptr = new rcl_node_t;
     *this->node_ptr = rcl_get_zero_initialized_node();
-    const char * name = "test_publisher_node";
+    constexpr char name[] = "test_publisher_node";
     rcl_node_options_t node_options = rcl_node_get_default_options();
     ret = rcl_node_init(this->node_ptr, name, "", this->context_ptr, &node_options);
     ASSERT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
@@ -76,6 +80,34 @@ class CLASSNAME (TestPublisherFixture, RMW_IMPLEMENTATION) : public ::testing::T
   }
 };
 
+class CLASSNAME (TestPublisherFixtureInit, RMW_IMPLEMENTATION)
+  : public CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION)
+{
+public:
+  const rosidl_message_type_support_t * ts =
+    ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, BasicTypes);
+  const char * topic_name = "chatter";
+  rcl_publisher_t publisher;
+  rcl_publisher_options_t publisher_options;
+
+  void SetUp() override
+  {
+    CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION) ::SetUp();
+    publisher = rcl_get_zero_initialized_publisher();
+    publisher_options = rcl_publisher_get_default_options();
+    rcl_ret_t ret = rcl_publisher_init(
+      &publisher, this->node_ptr, ts, topic_name, &publisher_options);
+    ASSERT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  }
+
+  void TearDown() override
+  {
+    rcl_ret_t ret = rcl_publisher_fini(&publisher, this->node_ptr);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+    CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION) ::TearDown();
+  }
+};
+
 /* Basic nominal test of a publisher.
  */
 TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_publisher_nominal) {
@@ -83,8 +115,8 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_publisher_nomin
   rcl_publisher_t publisher = rcl_get_zero_initialized_publisher();
   const rosidl_message_type_support_t * ts =
     ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, BasicTypes);
-  const char * topic_name = "chatter";
-  const char * expected_topic_name = "/chatter";
+  constexpr char topic_name[] = "chatter";
+  constexpr char expected_topic_name[] = "/chatter";
   rcl_publisher_options_t publisher_options = rcl_publisher_get_default_options();
   ret = rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
   ASSERT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
@@ -109,7 +141,7 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_publisher_nomin
   rcl_publisher_t publisher = rcl_get_zero_initialized_publisher();
   const rosidl_message_type_support_t * ts =
     ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, Strings);
-  const char * topic_name = "chatter";
+  constexpr char topic_name[] = "chatter";
   rcl_publisher_options_t publisher_options = rcl_publisher_get_default_options();
   ret = rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
   ASSERT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
@@ -187,7 +219,7 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_publisher_init_
   rcl_publisher_t publisher;
   const rosidl_message_type_support_t * ts =
     ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, BasicTypes);
-  const char * topic_name = "chatter";
+  constexpr char topic_name[] = "chatter";
   rcl_publisher_options_t default_publisher_options = rcl_publisher_get_default_options();
 
   // Check if null publisher is valid
@@ -216,6 +248,11 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_publisher_init_
   EXPECT_EQ(RCL_RET_NODE_INVALID, ret) << rcl_get_error_string().str;
   rcl_reset_error();
 
+  // Pass nullptr publisher to fini
+  ret = rcl_publisher_fini(nullptr, this->node_ptr);
+  EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, ret) << rcl_get_error_string().str;
+  rcl_reset_error();
+
   // Try passing null for publisher in init.
   ret = rcl_publisher_init(nullptr, this->node_ptr, ts, topic_name, &default_publisher_options);
   EXPECT_EQ(RCL_RET_INVALID_ARGUMENT, ret) << rcl_get_error_string().str;
@@ -305,7 +342,7 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_publisher_loan)
   rcl_publisher_t publisher = rcl_get_zero_initialized_publisher();
   const rosidl_message_type_support_t * ts =
     ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, Strings);
-  const char * topic_name = "chatter";
+  constexpr char topic_name[] = "chatter";
   rcl_publisher_options_t publisher_options = rcl_publisher_get_default_options();
   rcl_ret_t ret =
     rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
@@ -337,7 +374,7 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_invalid_publish
   rcl_publisher_t publisher = rcl_get_zero_initialized_publisher();
   const rosidl_message_type_support_t * ts =
     ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, Strings);
-  const char * topic_name = "chatter";
+  constexpr char topic_name[] = "chatter";
   rcl_publisher_options_t publisher_options = rcl_publisher_get_default_options();
   rcl_ret_t ret =
     rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
@@ -371,6 +408,7 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_invalid_publish
   rcl_publisher_impl_t * saved_impl = publisher.impl;
   rcl_context_t * saved_context = publisher.impl->context;
   rmw_publisher_t * saved_rmw_handle = publisher.impl->rmw_handle;
+  rmw_publisher_allocation_t * null_allocation_is_valid_arg = nullptr;
 
   // Change internal context to nullptr
   publisher.impl->context = nullptr;
@@ -391,14 +429,25 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_invalid_publish
   rcl_reset_error();
   EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publisher_assert_liveliness(&publisher));
   rcl_reset_error();
-  EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publish(&publisher, &msg, nullptr));
+  EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publish(&publisher, &msg, null_allocation_is_valid_arg));
   rcl_reset_error();
   EXPECT_EQ(
     RCL_RET_PUBLISHER_INVALID,
-    rcl_publish_serialized_message(&publisher, &serialized_msg, nullptr));
+    rcl_publish_serialized_message(&publisher, &serialized_msg, null_allocation_is_valid_arg));
   rcl_reset_error();
   publisher.impl->context = saved_context;
 
+  // nullptr arguments
+  EXPECT_EQ(
+    RCL_RET_INVALID_ARGUMENT, rcl_publish(&publisher, nullptr, null_allocation_is_valid_arg));
+  rcl_reset_error();
+  EXPECT_EQ(
+    RCL_RET_INVALID_ARGUMENT,
+    rcl_publish_serialized_message(&publisher, nullptr, null_allocation_is_valid_arg));
+  rcl_reset_error();
+  EXPECT_EQ(RCL_RET_INVALID_ARGUMENT, rcl_publisher_get_subscription_count(&publisher, nullptr));
+  rcl_reset_error();
+
   // Change internal rmw_handle to nullptr
   publisher.impl->rmw_handle = nullptr;
   EXPECT_FALSE(rcl_publisher_is_valid_except_context(&publisher));
@@ -422,11 +471,11 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_invalid_publish
   rcl_reset_error();
   EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publisher_assert_liveliness(&publisher));
   rcl_reset_error();
-  EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publish(&publisher, &msg, nullptr));
+  EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publish(&publisher, &msg, null_allocation_is_valid_arg));
   rcl_reset_error();
   EXPECT_EQ(
     RCL_RET_PUBLISHER_INVALID,
-    rcl_publish_serialized_message(&publisher, &serialized_msg, nullptr));
+    rcl_publish_serialized_message(&publisher, &serialized_msg, null_allocation_is_valid_arg));
   rcl_reset_error();
   publisher.impl->rmw_handle = saved_rmw_handle;
 
@@ -453,11 +502,11 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_invalid_publish
   rcl_reset_error();
   EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publisher_assert_liveliness(&publisher));
   rcl_reset_error();
-  EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publish(&publisher, &msg, nullptr));
+  EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publish(&publisher, &msg, null_allocation_is_valid_arg));
   rcl_reset_error();
   EXPECT_EQ(
     RCL_RET_PUBLISHER_INVALID,
-    rcl_publish_serialized_message(&publisher, &serialized_msg, nullptr));
+    rcl_publish_serialized_message(&publisher, &serialized_msg, null_allocation_is_valid_arg));
   rcl_reset_error();
   publisher.impl = saved_impl;
 
@@ -483,10 +532,310 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_invalid_publish
   rcl_reset_error();
   EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publisher_assert_liveliness(nullptr));
   rcl_reset_error();
-  EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publish(nullptr, &msg, nullptr));
+  EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_publish(nullptr, &msg, null_allocation_is_valid_arg));
   rcl_reset_error();
   EXPECT_EQ(
     RCL_RET_PUBLISHER_INVALID,
-    rcl_publish_serialized_message(nullptr, &serialized_msg, nullptr));
+    rcl_publish_serialized_message(nullptr, &serialized_msg, null_allocation_is_valid_arg));
+  rcl_reset_error();
+}
+
+// Mocking rmw_publisher_count_matched_subscriptions to make
+// rcl_publisher_get_subscription_count fail
+TEST_F(
+  CLASSNAME(TestPublisherFixtureInit, RMW_IMPLEMENTATION),
+  test_mock_publisher_get_subscription_count)
+{
+  auto mock = mocking_utils::patch_and_return(
+    "lib:rcl", rmw_publisher_count_matched_subscriptions, RMW_RET_BAD_ALLOC);
+
+  // Now normal usage of the function rcl_publisher_get_subscription_count returning
+  // unexpected RMW_RET_BAD_ALLOC
+  size_t count_size = 2u;
+  EXPECT_EQ(
+    RCL_RET_BAD_ALLOC, rcl_publisher_get_subscription_count(&publisher, &count_size));
+  EXPECT_EQ(2u, count_size);
+  rcl_reset_error();
+}
+
+// Mocking rmw_publisher_assert_liveliness to make
+// rcl_publisher_assert_liveliness fail
+TEST_F(CLASSNAME(TestPublisherFixtureInit, RMW_IMPLEMENTATION), test_mock_assert_liveliness) {
+  auto mock = mocking_utils::patch_and_return(
+    "lib:rcl", rmw_publisher_assert_liveliness, RMW_RET_ERROR);
+
+  // Now normal usage of the function rcl_publisher_assert_liveliness returning
+  // unexpected RMW_RET_ERROR
+  EXPECT_EQ(
+    RCL_RET_ERROR, rcl_publisher_assert_liveliness(&publisher));
+  EXPECT_TRUE(rcl_error_is_set());
+  rcl_reset_error();
+}
+
+// Mocking rmw_publish to make rcl_publish fail
+TEST_F(CLASSNAME(TestPublisherFixtureInit, RMW_IMPLEMENTATION), test_mock_publish) {
+  auto mock = mocking_utils::patch_and_return("lib:rcl", rmw_publish, RMW_RET_ERROR);
+
+  // Test normal usage of the function rcl_publish returning unexpected RMW_RET_ERROR
+  test_msgs__msg__BasicTypes msg;
+  test_msgs__msg__BasicTypes__init(&msg);
+  msg.int64_value = 42;
+  rcl_ret_t ret = rcl_publish(&publisher, &msg, nullptr);
+  test_msgs__msg__BasicTypes__fini(&msg);
+  EXPECT_EQ(RCL_RET_ERROR, ret) << rcl_get_error_string().str;
+  EXPECT_TRUE(rcl_error_is_set());
+  rcl_reset_error();
+}
+
+// Mocking rmw_publish_serialized_message to make rcl_publish_serialized_message fail
+TEST_F(
+  CLASSNAME(TestPublisherFixtureInit, RMW_IMPLEMENTATION), test_mock_publish_serialized_message)
+{
+  rcl_serialized_message_t serialized_msg = rmw_get_zero_initialized_serialized_message();
+  size_t initial_size_serialized = 0u;
+  rcl_allocator_t allocator = rcl_get_default_allocator();
+  ASSERT_EQ(
+    RCL_RET_OK, rmw_serialized_message_init(
+      &serialized_msg, initial_size_serialized, &allocator)) << rcl_get_error_string().str;
+  constexpr char test_string[] = "testing";
+  test_msgs__msg__Strings msg;
+  test_msgs__msg__Strings__init(&msg);
+  OSRF_TESTING_TOOLS_CPP_SCOPE_EXIT(
+  {
+    test_msgs__msg__Strings__fini(&msg);
+  });
+
+  ASSERT_TRUE(rosidl_runtime_c__String__assign(&msg.string_value, test_string));
+  ASSERT_STREQ(msg.string_value.data, test_string);
+  rcl_ret_t ret = rmw_serialize(&msg, ts, &serialized_msg);
+  ASSERT_EQ(RMW_RET_OK, ret);
+
+  rmw_ret_t rmw_publish_serialized_return = RMW_RET_ERROR;
+  auto mock = mocking_utils::patch_and_return(
+    "lib:rcl", rmw_publish_serialized_message, rmw_publish_serialized_return);
+  {
+    // Test normal usage of the function rcl_publish_serialized_message
+    // returning unexpected RMW_RET_ERROR
+    ret = rcl_publish_serialized_message(&publisher, &serialized_msg, nullptr);
+    EXPECT_EQ(RCL_RET_ERROR, ret) << rcl_get_error_string().str;
+    EXPECT_TRUE(rcl_error_is_set());
+    rcl_reset_error();
+  }
+  {
+    // Repeat, but now returning BAD_ALLOC
+    rmw_publish_serialized_return = RMW_RET_BAD_ALLOC;
+    ret = rcl_publish_serialized_message(&publisher, &serialized_msg, nullptr);
+    EXPECT_EQ(RCL_RET_BAD_ALLOC, ret) << rcl_get_error_string().str;
+    EXPECT_TRUE(rcl_error_is_set());
+    rcl_reset_error();
+  }
+}
+
+// Define dummy comparison operators for rcutils_allocator_t type for use with the Mimick Library
+MOCKING_UTILS_BOOL_OPERATOR_RETURNS_FALSE(rcutils_allocator_t, ==)
+MOCKING_UTILS_BOOL_OPERATOR_RETURNS_FALSE(rcutils_allocator_t, <)
+MOCKING_UTILS_BOOL_OPERATOR_RETURNS_FALSE(rcutils_allocator_t, >)
+MOCKING_UTILS_BOOL_OPERATOR_RETURNS_FALSE(rcutils_allocator_t, !=)
+
+TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_mock_publisher_init) {
+  rcl_publisher_t publisher = rcl_get_zero_initialized_publisher();
+  const rosidl_message_type_support_t * ts =
+    ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, Strings);
+  constexpr char topic_name[] = "chatter";
+  rcl_publisher_options_t publisher_options = rcl_publisher_get_default_options();
+  rcl_ret_t ret = RCL_RET_OK;
+
+  auto mock = mocking_utils::patch_and_return(
+    "lib:rcl", rcutils_string_map_init, RCUTILS_RET_ERROR);
+  ret = rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
+  EXPECT_EQ(RCL_RET_ERROR, ret) << rcl_get_error_string().str;
+  rcl_reset_error();
+}
+
+TEST_F(
+  CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_mock_publisher_init_fail_qos)
+{
+  auto mock = mocking_utils::patch_and_return(
+    "lib:rcl", rmw_publisher_get_actual_qos, RMW_RET_ERROR);
+
+  rcl_publisher_t publisher = rcl_get_zero_initialized_publisher();
+  const rosidl_message_type_support_t * ts =
+    ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, Strings);
+  constexpr char topic_name[] = "chatter";
+  rcl_publisher_options_t publisher_options = rcl_publisher_get_default_options();
+
+  rcl_ret_t ret =
+    rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
+  EXPECT_EQ(RCL_RET_ERROR, ret) << rcl_get_error_string().str;
   rcl_reset_error();
 }
+
+// Tests for loaned msgs functions. Mocked as the rmw tier1 vendors don't support it
+TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_mock_loaned_functions) {
+  rcl_publisher_t publisher = rcl_get_zero_initialized_publisher();
+  rcl_publisher_t not_init_publisher = rcl_get_zero_initialized_publisher();
+  const rosidl_message_type_support_t * ts =
+    ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, BasicTypes);
+  constexpr char topic_name[] = "chatter";
+  constexpr char expected_topic_name[] = "/chatter";
+  rcl_publisher_options_t publisher_options = rcl_publisher_get_default_options();
+
+  rcl_ret_t ret = rcl_publisher_init(
+    &publisher, this->node_ptr, ts, topic_name, &publisher_options);
+  ASSERT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  OSRF_TESTING_TOOLS_CPP_SCOPE_EXIT(
+  {
+    ret = rcl_publisher_fini(&publisher, this->node_ptr);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  });
+
+  EXPECT_EQ(strcmp(rcl_publisher_get_topic_name(&publisher), expected_topic_name), 0);
+  test_msgs__msg__BasicTypes msg;
+  test_msgs__msg__BasicTypes__init(&msg);
+  msg.int64_value = 42;
+  void * msg_pointer = &msg;
+  rmw_publisher_allocation_t * null_allocation_is_valid_arg = nullptr;
+
+  {
+    // mocked, publish nominal usage
+    auto mock = mocking_utils::patch_and_return("lib:rcl", rmw_publish_loaned_message, RMW_RET_OK);
+    EXPECT_EQ(RCL_RET_OK, rcl_publish_loaned_message(&publisher, &msg, nullptr));
+  }
+  {
+    // bad params publish
+    EXPECT_EQ(
+      RCL_RET_PUBLISHER_INVALID,
+      rcl_publish_loaned_message(nullptr, &msg, null_allocation_is_valid_arg));
+    EXPECT_EQ(
+      RCL_RET_PUBLISHER_INVALID,
+      rcl_publish_loaned_message(&not_init_publisher, &msg, null_allocation_is_valid_arg));
+    EXPECT_EQ(
+      RCL_RET_INVALID_ARGUMENT,
+      rcl_publish_loaned_message(&publisher, nullptr, null_allocation_is_valid_arg));
+  }
+  {
+    // mocked, failure publish
+    auto mock = mocking_utils::patch_and_return(
+      "lib:rcl", rmw_publish_loaned_message, RMW_RET_ERROR);
+    EXPECT_EQ(RCL_RET_ERROR, rcl_publish_loaned_message(&publisher, &msg, nullptr));
+  }
+  {
+    // mocked, borrow loaned nominal usage
+    auto mock = mocking_utils::patch_and_return("lib:rcl", rmw_borrow_loaned_message, RMW_RET_OK);
+    EXPECT_EQ(RCL_RET_OK, rcl_borrow_loaned_message(&publisher, ts, &msg_pointer));
+  }
+  {
+    // bad params borrow loaned
+    EXPECT_EQ(RCL_RET_PUBLISHER_INVALID, rcl_borrow_loaned_message(nullptr, ts, &msg_pointer));
+    EXPECT_EQ(
+      RCL_RET_PUBLISHER_INVALID, rcl_borrow_loaned_message(&not_init_publisher, ts, &msg_pointer));
+  }
+  {
+    // mocked, nominal return loaned message
+    auto mock = mocking_utils::patch_and_return(
+      "lib:rcl", rmw_return_loaned_message_from_publisher, RMW_RET_OK);
+    EXPECT_EQ(RCL_RET_OK, rcl_return_loaned_message_from_publisher(&publisher, &msg));
+  }
+  {
+    // bad params return loaned message
+    EXPECT_EQ(
+      RCL_RET_PUBLISHER_INVALID,
+      rcl_return_loaned_message_from_publisher(nullptr, &msg));
+    EXPECT_EQ(
+      RCL_RET_PUBLISHER_INVALID,
+      rcl_return_loaned_message_from_publisher(&not_init_publisher, &msg));
+    EXPECT_EQ(
+      RCL_RET_INVALID_ARGUMENT,
+      rcl_return_loaned_message_from_publisher(&publisher, nullptr));
+  }
+
+  test_msgs__msg__BasicTypes__fini(&msg);
+  ASSERT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+}
+
+// Tests mocking ini/fini functions for specific failures
+TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_mocks_fail_publisher_init) {
+  rcl_publisher_t publisher = rcl_get_zero_initialized_publisher();
+  const rosidl_message_type_support_t * ts =
+    ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, Strings);
+  constexpr char topic_name[] = "chatter";
+  rcl_publisher_options_t publisher_options = rcl_publisher_get_default_options();
+  rcl_ret_t ret = RCL_RET_OK;
+
+  {
+    // Internal rmw failure validating node name
+    auto mock = mocking_utils::patch_and_return("lib:rcl", rmw_validate_node_name, RMW_RET_ERROR);
+    ret = rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
+    EXPECT_EQ(RCL_RET_ERROR, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+  }
+  {
+    // Internal rmw failure validating node name
+    auto mock = mocking_utils::patch_and_return(
+      "lib:rcl", rmw_validate_node_name, RMW_RET_INVALID_ARGUMENT);
+    ret = rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
+    EXPECT_EQ(RCL_RET_ERROR, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+  }
+  {
+    // Internal failure when fini rcutils_string_map returns error, targets substitution_map fini
+    auto mock = mocking_utils::patch_and_return(
+      "lib:rcl", rcutils_string_map_fini, RCUTILS_RET_ERROR);
+    ret = rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
+    EXPECT_EQ(RCL_RET_ERROR, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+  }
+  {
+    // Internal failure when fini rcutils_string_map returns error, targets rcl_remap_topic_name
+    auto mock = mocking_utils::patch(
+      "lib:rcl", rcutils_string_map_init, [](auto...) {
+        static int counter = 1;
+        if (counter == 1) {
+          counter++;
+          return RCUTILS_RET_OK;
+        } else {
+          // This makes rcl_remap_topic_name fail
+          return RCUTILS_RET_ERROR;
+        }
+      });
+    ret = rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
+    EXPECT_EQ(RCL_RET_ERROR, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+  }
+  {
+    // Internal rmw failure validating topic name
+    auto mock = mocking_utils::patch_and_return(
+      "lib:rcl", rmw_validate_full_topic_name, RMW_RET_ERROR);
+    ret = rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
+    EXPECT_EQ(RCL_RET_ERROR, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+  }
+  {
+    // Internal rmw failure validating node name, returns OK but the result is set to error
+    auto mock = mocking_utils::patch(
+      "lib:rcl", rmw_validate_full_topic_name, [](auto, int * result, auto) {
+        *result = RMW_TOPIC_INVALID_NOT_ABSOLUTE;
+        return RMW_RET_OK;
+      });
+    ret = rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
+    EXPECT_EQ(RCL_RET_TOPIC_NAME_INVALID, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+  }
+}
+
+// Test mocked fail fini publisher
+TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_mock_publisher_fini_fail) {
+  rcl_publisher_t publisher = rcl_get_zero_initialized_publisher();
+  const rosidl_message_type_support_t * ts =
+    ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, BasicTypes);
+  constexpr char topic_name[] = "chatter";
+  rcl_publisher_options_t publisher_options = rcl_publisher_get_default_options();
+  rcl_ret_t ret = rcl_publisher_init(
+    &publisher, this->node_ptr, ts, topic_name, &publisher_options);
+  ASSERT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+
+  // Internal rmw failure destroying publisher
+  auto mock = mocking_utils::patch_and_return("lib:rcl", rmw_destroy_publisher, RMW_RET_ERROR);
+  ret = rcl_publisher_fini(&publisher, this->node_ptr);
+  EXPECT_EQ(RCL_RET_ERROR, ret) << rcl_get_error_string().str;
+}