6 files changed, 32 insertions, 23 deletions
diff --git a/tools/interface_generator/BUILD.bazel b/tools/interface_generator/BUILD.bazel
index 15fbb5d..e62d7b9 100644
--- a/tools/interface_generator/BUILD.bazel
+++ b/tools/interface_generator/BUILD.bazel
@@ -1,6 +1,7 @@
 load("@rules_python//python:pip.bzl", "compile_pip_requirements")
 load("@pip//:requirements.bzl", "requirement")
-load(":defs.bzl", "generate_interface", "py_pytest")
+load(":defs.bzl", "generate_interface")
+load("//private:defs.bzl", "py_pytest")
 
 package(default_visibility = ["//visibility:public"])
 
diff --git a/tools/interface_generator/MODULE.bazel b/tools/interface_generator/MODULE.bazel
index b5cbae6..53b2ba4 100644
--- a/tools/interface_generator/MODULE.bazel
+++ b/tools/interface_generator/MODULE.bazel
@@ -5,6 +5,9 @@
 # For more details, please check https://github.com/bazelbuild/bazel/issues/18958
 ###############################################################################
 
+module(name = "interface_generator", version = "0.1.0")
+
+# external dependencies
 bazel_dep(name = "googletest", version = "1.15.2")
 bazel_dep(name = "rules_python", version = "0.34.0")
 
diff --git a/tools/interface_generator/defs.bzl b/tools/interface_generator/defs.bzl
index 6f02b1f..d5c6f91 100644
--- a/tools/interface_generator/defs.bzl
+++ b/tools/interface_generator/defs.bzl
@@ -1,5 +1,3 @@
-load("@pip//:requirements.bzl", "requirement")
-
 def _generate_interface_impl(ctx):
     out_hdrs = [
         ctx.actions.declare_file(ctx.attr.interface + ".h"),
@@ -53,23 +51,3 @@ def generate_interface(name, interface, license, visibility = None):
         license = license,
         visibility = visibility,
     )
-
-def py_pytest(name, srcs, deps = [], **kwargs):
-    native.py_test(
-        name = name,
-        srcs = ["//:pytest_wrapper.py"],
-        main = "//:pytest_wrapper.py",
-        data = srcs,
-        args = [
-            "--black",
-            "--pylint",
-            #"--mypy",
-        ] + ["$(location :%s)" % x for x in srcs],
-        deps = [
-            requirement("pytest"),
-            requirement("pytest-black"),
-            requirement("pytest-pylint"),
-            requirement("pytest-mypy"),
-        ] + deps,
-        **kwargs
-    )
diff --git a/tools/interface_generator/private/BUILD.bazel b/tools/interface_generator/private/BUILD.bazel
new file mode 100644
index 0000000..46436ee
--- /dev/null
+++ b/tools/interface_generator/private/BUILD.bazel
@@ -0,0 +1,5 @@
+""" targets internal to the tool and rule """
+
+package(default_visibility = ["//:__pkg__"])
+
+exports_files(["pytest_wrapper.py"])
diff --git a/tools/interface_generator/private/defs.bzl b/tools/interface_generator/private/defs.bzl
new file mode 100644
index 0000000..080f19a
--- /dev/null
+++ b/tools/interface_generator/private/defs.bzl
@@ -0,0 +1,22 @@
+load("@pip//:requirements.bzl", "requirement")
+
+def py_pytest(name, srcs, deps = [], **kwargs):
+    native.py_test(
+        name = name,
+        srcs = ["//private:pytest_wrapper.py"],
+        main = "//private:pytest_wrapper.py",
+        data = srcs,
+        args = [
+            "--black",
+            "--pylint",
+            #"--mypy",
+        ] + ["$(location :%s)" % x for x in srcs],
+        deps = [
+            requirement("pytest"),
+            requirement("pytest-black"),
+            requirement("pytest-pylint"),
+            requirement("pytest-mypy"),
+        ] + deps,
+        **kwargs
+    )
+
diff --git a/tools/interface_generator/pytest_wrapper.py b/tools/interface_generator/private/pytest_wrapper.py
index b4def3b..b4def3b 100755
--- a/tools/interface_generator/pytest_wrapper.py
+++ b/tools/interface_generator/private/pytest_wrapper.py