diff --git a/HISTORY.rst b/HISTORY.rst
index 30960775..c20b419a 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -45,8 +45,8 @@ Please check `Migration guide from 5.x to 6.0 <https://docs.platformio.org/en/la
 * **Unit Testing**
 
   - New `Unit Testing <https://docs.platformio.org/en/latest/advanced/unit-testing/index.html>`_ engine and documentation
+  - Added support for `Test Hierarchies <https://docs.platformio.org/en/latest/advanced/unit-testing/structure.html>`_ (`issue #4135 <https://github.com/platformio/platformio-core/issues/4135>`_)
   - Added a new "test" `build configuration <https://docs.platformio.org/en/latest/projectconf/build_configurations.html>`__
-  - Added support for test hierarchies (nested test suites) (`issue #4135 <https://github.com/platformio/platformio-core/issues/4135>`_)
   - Generate reports in JUnit and JSON formats using the `pio test --output-format <https://docs.platformio.org/en/latest/core/userguide/cmd_test.html#cmdoption-pio-test-output-format>`__ option  (`issue #2891 <https://github.com/platformio/platformio-core/issues/2891>`_)
   - Provide more information when the native program crashed on a host (errored with a negative return code) (`issue #3429 <https://github.com/platformio/platformio-core/issues/3429>`_)
   - Fixed an issue when command line parameters ("--ignore", "--filter") do not override values defined in the |PIOCONF| (`issue #3845 <https://github.com/platformio/platformio-core/issues/3845>`_)
diff --git a/platformio/builder/tools/piotest.py b/platformio/builder/tools/piotest.py
index b9c2444a..0ebe7637 100644
--- a/platformio/builder/tools/piotest.py
+++ b/platformio/builder/tools/piotest.py
@@ -16,6 +16,7 @@ from __future__ import absolute_import
 
 import os
 
+from platformio.builder.tools import platformio as piotool
 from platformio.test.result import TestSuite
 from platformio.test.runners.factory import TestRunnerFactory
 
@@ -23,10 +24,24 @@ from platformio.test.runners.factory import TestRunnerFactory
 def ConfigureTestTarget(env):
     env.Append(
         CPPDEFINES=["UNIT_TEST", "PIO_UNIT_TESTING"],
-        PIOTEST_SRC_FILTER=["+<*.cpp>", "+<*.c>"],
+        PIOTEST_SRC_FILTER=[f"+<*.{ext}>" for ext in piotool.SRC_BUILD_EXT],
     )
 
     if "PIOTEST_RUNNING_NAME" in env:
+        test_name = env["PIOTEST_RUNNING_NAME"]
+        while True:
+            test_name = os.path.dirname(test_name)  # parent dir
+            # skip nested tests (user's side issue?)
+            if not test_name or os.path.basename(test_name).startswith("test_"):
+                break
+            env.Append(
+                PIOTEST_SRC_FILTER=[
+                    f"+<{test_name}{os.path.sep}*.{ext}>"
+                    for ext in piotool.SRC_BUILD_EXT
+                ],
+                CPPPATH=[os.path.join("$PROJECT_TEST_DIR", test_name)],
+            )
+
         env.Append(
             PIOTEST_SRC_FILTER=[f"+<$PIOTEST_RUNNING_NAME{os.path.sep}>"],
             CPPPATH=[os.path.join("$PROJECT_TEST_DIR", "$PIOTEST_RUNNING_NAME")],
diff --git a/tests/commands/test_test.py b/tests/commands/test_test.py
index d8780fae..a68a20fe 100644
--- a/tests/commands/test_test.py
+++ b/tests/commands/test_test.py
@@ -235,16 +235,18 @@ int main() {
     assert all(f in result.output for f in ("setUp called", "tearDown called"))
 
 
-def test_unity_custom_config(clirunner, validate_cliresult, tmpdir):
-    project_dir = tmpdir.mkdir("project")
-    project_dir.join("platformio.ini").write(
+def test_unity_custom_config(clirunner, validate_cliresult, tmp_path: Path):
+    project_dir = tmp_path / "project"
+    project_dir.mkdir()
+    (project_dir / "platformio.ini").write_text(
         """
 [env:native]
 platform = native
 """
     )
-    test_dir = project_dir.mkdir("test")
-    test_dir.join("unity_config.h").write(
+    test_dir = project_dir / "test" / "native" / "test_component"
+    test_dir.mkdir(parents=True)
+    (test_dir.parent / "unity_config.h").write_text(
         """
 #include <stdio.h>
 
@@ -254,7 +256,7 @@ platform = native
 #define UNITY_OUTPUT_FLUSH()    fflush(stdout)
 """
     )
-    test_dir.join("test_main.c").write(
+    (test_dir / "test_main.c").write_text(
         """
 #include <stdio.h>
 #include <unity.h>