diff --git a/.bazelignore b/.bazelignore
index 1e107f52..d88dd6d6 100644
--- a/.bazelignore
+++ b/.bazelignore
@@ -1 +1,2 @@
 examples
+bazel-rules_ros2
diff --git a/ros2/cc_defs.bzl b/ros2/cc_defs.bzl
index 44285fad..8b79d2fb 100644
--- a/ros2/cc_defs.bzl
+++ b/ros2/cc_defs.bzl
@@ -64,14 +64,15 @@ def ros2_c_binary(name, ros2_package_name = None, **kwargs):
     """
     _ros2_cc_target(cc_binary, "c", name, ros2_package_name, **kwargs)
 
-def _ros2_cpp_exec(target, name, ros2_package_name = None, set_up_ament = False, **kwargs):
-    if set_up_ament == False:
+def _ros2_cpp_exec(target, name, ros2_package_name = None, set_up_ament = False, set_up_ros_home = False, **kwargs):
+    if not (set_up_ament or set_up_ros_home):
         _ros2_cc_target(target, "cpp", name, ros2_package_name, **kwargs)
         return
 
     target_impl = name + "_impl"
     tags = kwargs.pop("tags", [])
     visibility = kwargs.pop("visibility", None)
+    size = kwargs.pop("size", None)
     _ros2_cc_target(cc_binary, "cpp", target_impl, ros2_package_name, tags = ["manual"], **kwargs)
 
     is_test = target == cc_test
@@ -82,7 +83,9 @@ def _ros2_cpp_exec(target, name, ros2_package_name = None, set_up_ament = False,
         deps = [target_impl],
         template = "@com_github_mvukov_rules_ros2//ros2:launch.sh.tpl",
         substitutions = {
-            "{entry_point}": "$(rootpath {})".format(target_impl),
+            "{{set_up_ros_home}}": "set_up_ros_home" if set_up_ros_home else "",
+            "{{set_up_ament}}": "set_up_ament" if set_up_ament else "",
+            "{{entry_point}}": "$(rootpath {})".format(target_impl),
         },
         tags = ["manual"],
         data = [target_impl],
@@ -92,6 +95,7 @@ def _ros2_cpp_exec(target, name, ros2_package_name = None, set_up_ament = False,
     sh_target = native.sh_test if is_test else native.sh_binary
     sh_target(
         name = name,
+        size = size,
         srcs = [launcher],
         data = [target_impl],
         tags = tags,
@@ -110,9 +114,11 @@ def ros2_cpp_binary(name, ros2_package_name = None, set_up_ament = False, **kwar
         set_up_ament: If true, sets up ament file tree for the binary target.
         **kwargs: https://bazel.build/reference/be/common-definitions#common-attributes-binaries
     """
+    if "set_up_ros_home" in kwargs:
+        fail("set_up_ros_home only makes sense for test targets.")
     _ros2_cpp_exec(cc_binary, name, ros2_package_name, set_up_ament, **kwargs)
 
-def ros2_cpp_test(name, ros2_package_name = None, set_up_ament = False, **kwargs):
+def ros2_cpp_test(name, ros2_package_name = None, set_up_ament = False, set_up_ros_home = True, **kwargs):
     """ Defines a ROS 2 C++ test.
 
     Adds common ROS 2 C++ definitions on top of a cc_test.
@@ -122,9 +128,7 @@ def ros2_cpp_test(name, ros2_package_name = None, set_up_ament = False, **kwargs
         ros2_package_name: If given, defines a ROS package name for the target.
             Otherwise, the `name` is used as the package name.
         set_up_ament: If true, sets up ament file tree for the test target.
+        set_up_ros_home: If true, sets up ROS_HOME for the test target.
         **kwargs: https://bazel.build/reference/be/common-definitions#common-attributes-tests
     """
-    env = kwargs.pop("env", {})
-    env["ROS_HOME"] = env.get("ROS_HOME", "$TEST_UNDECLARED_OUTPUTS_DIR")
-    env["ROS_LOG_DIR"] = env.get("ROS_LOG_DIR", "$TEST_UNDECLARED_OUTPUTS_DIR")
-    _ros2_cpp_exec(cc_test, name, ros2_package_name, set_up_ament, env = env, **kwargs)
+    _ros2_cpp_exec(cc_test, name, ros2_package_name, set_up_ament, set_up_ros_home, **kwargs)
diff --git a/ros2/launch.sh.tpl b/ros2/launch.sh.tpl
index b3d2f0a2..60e91515 100644
--- a/ros2/launch.sh.tpl
+++ b/ros2/launch.sh.tpl
@@ -2,10 +2,21 @@
 
 set -o errexit -o nounset -o pipefail
 
-ament_prefix_path="{{ament_prefix_path}}"
-if [ -z "${ament_prefix_path}" ]; then
+if [ -n "{{set_up_ros_home}}" ]; then
+  if [ -z "${ROS_HOME:-}" ] && [ -z "${ROS_LOG_DIR:-}" ]; then
+    ros_output_dir="${TEST_UNDECLARED_OUTPUTS_DIR:-${TEST_TMPDIR:-}}"
+    if [ -n "${ros_output_dir}" ]; then
+      export ROS_HOME="${ros_output_dir}"
+      export ROS_LOG_DIR="${ros_output_dir}"
+    fi
+  fi
+fi
+
+if [ -n "{{set_up_ament}}" ]; then
   unset AMENT_PREFIX_PATH
-  {entry_point} "$@"
-else
-  AMENT_PREFIX_PATH="${ament_prefix_path}" {entry_point} "$@"
+  if [ -n "{{ament_prefix_path}}" ]; then
+    export AMENT_PREFIX_PATH="{{ament_prefix_path}}"
+  fi
 fi
+
+"{{entry_point}}" "$@"
diff --git a/ros2/py_defs.bzl b/ros2/py_defs.bzl
index 0d251c2e..7bf65b9d 100644
--- a/ros2/py_defs.bzl
+++ b/ros2/py_defs.bzl
@@ -5,14 +5,15 @@ load("@com_github_mvukov_rules_ros2//ros2:ament.bzl", "sh_launcher")
 load("@com_github_mvukov_rules_ros2//third_party:symlink.bzl", "symlink")
 load("@rules_python//python:defs.bzl", "py_binary", "py_test")
 
-def _ros2_py_exec(target, name, srcs, main, set_up_ament, **kwargs):
-    if set_up_ament == False:
+def _ros2_py_exec(target, name, srcs, main, set_up_ament = False, set_up_ros_home = False, **kwargs):
+    if not (set_up_ament or set_up_ros_home):
         target(name = name, srcs = srcs, main = main, **kwargs)
         return
 
     target_impl = name + "_impl"
     tags = kwargs.pop("tags", [])
     visibility = kwargs.pop("visibility", None)
+    size = kwargs.pop("size", None)
     target(name = target_impl, srcs = srcs, main = main, tags = ["manual"], **kwargs)
 
     is_test = target == py_test
@@ -31,7 +32,9 @@ def _ros2_py_exec(target, name, srcs, main, set_up_ament, **kwargs):
         deps = [target_impl],
         template = "@com_github_mvukov_rules_ros2//ros2:launch.sh.tpl",
         substitutions = {
-            "{entry_point}": "$(rootpath {})".format(target_impl_symlink),
+            "{{set_up_ros_home}}": "set_up_ros_home" if set_up_ros_home else "",
+            "{{set_up_ament}}": "set_up_ament" if set_up_ament else "",
+            "{{entry_point}}": "$(rootpath {})".format(target_impl_symlink),
         },
         tags = ["manual"],
         data = [target_impl_symlink],
@@ -41,6 +44,7 @@ def _ros2_py_exec(target, name, srcs, main, set_up_ament, **kwargs):
     sh_target = native.sh_test if is_test else native.sh_binary
     sh_target(
         name = name,
+        size = size,
         srcs = [launcher],
         data = [target_impl_symlink],
         tags = tags,
@@ -57,9 +61,11 @@ def ros2_py_binary(name, srcs, main, set_up_ament = False, **kwargs):
         set_up_ament: If true, sets up ament file tree for the binary target.
         **kwargs: https://bazel.build/reference/be/common-definitions#common-attributes-binaries
     """
+    if "set_up_ros_home" in kwargs:
+        fail("set_up_ros_home only makes sense for test targets.")
     _ros2_py_exec(py_binary, name, srcs, main, set_up_ament, **kwargs)
 
-def ros2_py_test(name, srcs, main, set_up_ament = False, **kwargs):
+def ros2_py_test(name, srcs, main, set_up_ament = False, set_up_ros_home = True, **kwargs):
     """ Defines a ROS 2 Python test.
 
     Args:
@@ -67,6 +73,7 @@ def ros2_py_test(name, srcs, main, set_up_ament = False, **kwargs):
         srcs: List of source files.
         main: Source file to use as entrypoint.
         set_up_ament: If true, sets up ament file tree for the test target.
+        set_up_ros_home: If true, sets up ROS_HOME for the test target.
         **kwargs: https://bazel.build/reference/be/common-definitions#common-attributes-tests
     """
-    _ros2_py_exec(py_test, name, srcs, main, set_up_ament, **kwargs)
+    _ros2_py_exec(py_test, name, srcs, main, set_up_ament, set_up_ros_home, **kwargs)
diff --git a/ros2/pytest_wrapper.py.tpl b/ros2/pytest_wrapper.py.tpl
index 5d0983f6..280e6b0c 100644
--- a/ros2/pytest_wrapper.py.tpl
+++ b/ros2/pytest_wrapper.py.tpl
@@ -33,7 +33,7 @@ def finalize_coverage_session(coverage_session: coverage.Coverage) -> None:
 
 
 def main() -> None:
-    test_outputs_dir = os.environ.get('TEST_UNDECLARED_OUTPUTS_DIR')
+    test_outputs_dir = os.environ.get('TEST_UNDECLARED_OUTPUTS_DIR') or os.environ.get('TEST_TMPDIR')
     if test_outputs_dir:
         os.environ['ROS_HOME'] = test_outputs_dir
         os.environ['ROS_LOG_DIR'] = test_outputs_dir
diff --git a/ros2/test.py.tpl b/ros2/test.py.tpl
index a820f147..1b46b934 100644
--- a/ros2/test.py.tpl
+++ b/ros2/test.py.tpl
@@ -17,7 +17,7 @@ sys.argv = sys.argv[:1] + [
     LAUNCH_FILE,
 ] + sys.argv[1:]
 
-test_outputs_dir = os.environ.get('TEST_UNDECLARED_OUTPUTS_DIR')
+test_outputs_dir = os.environ.get('TEST_UNDECLARED_OUTPUTS_DIR') or os.environ.get('TEST_TMPDIR')
 if test_outputs_dir:
     os.environ['ROS_HOME'] = test_outputs_dir
     os.environ['ROS_LOG_DIR'] = test_outputs_dir
diff --git a/ros2/test/BUILD.bazel b/ros2/test/BUILD.bazel
index 169a974f..15b9b8ff 100644
--- a/ros2/test/BUILD.bazel
+++ b/ros2/test/BUILD.bazel
@@ -3,6 +3,7 @@
 
 load("@com_github_mvukov_rules_ros2//ros2:cc_defs.bzl", "ros2_cpp_test")
 load("@com_github_mvukov_rules_ros2//ros2:interfaces.bzl", "py_ros2_interface_library", "ros2_interface_library")
+load("@com_github_mvukov_rules_ros2//ros2:py_defs.bzl", "ros2_py_test")
 load("@rules_python//python:defs.bzl", "py_test")
 
 py_test(
@@ -49,3 +50,11 @@ ros2_cpp_test(
     srcs = ["test_rclcpp.cpp"],
     deps = ["@ros2_rclcpp//:rclcpp"],
 )
+
+ros2_py_test(
+    name = "test_rclpy",
+    size = "small",
+    srcs = ["test_rclpy.py"],
+    main = "test_rclpy.py",
+    deps = ["@ros2_rclpy//:rclpy"],
+)
diff --git a/ros2/test/test_rclpy.py b/ros2/test/test_rclpy.py
new file mode 100644
index 00000000..153c2006
--- /dev/null
+++ b/ros2/test/test_rclpy.py
@@ -0,0 +1,3 @@
+import rclpy
+
+rclpy.init()