From 8848eddedff1d8f26887f05cd0ff0363b7e91a5c Mon Sep 17 00:00:00 2001
From: Michael Vogt <mvo@ubuntu.com>
Date: Mon, 6 Nov 2023 11:45:45 +0100
Subject: [PATCH] osbuild: add new testutil.imports module to help test stages

This commit adds `osbuild.testutil.imports.import_module_from_path`
that can be used to import arbitrary python source files. This
allows importing files from the stages directory that have a
non python friendly filename like `org.osbuild.kickstart`.
---
 osbuild/testutil/__init__.py      |  3 +++
 osbuild/testutil/imports.py       | 27 +++++++++++++++++++++++++++
 test/mod/test_testutil_imports.py | 17 +++++++++++++++++
 3 files changed, 47 insertions(+)
 create mode 100644 osbuild/testutil/__init__.py
 create mode 100644 osbuild/testutil/imports.py
 create mode 100644 test/mod/test_testutil_imports.py

diff --git a/osbuild/testutil/__init__.py b/osbuild/testutil/__init__.py
new file mode 100644
index 000000000..09d6d43b2
--- /dev/null
+++ b/osbuild/testutil/__init__.py
@@ -0,0 +1,3 @@
+"""
+Test related utilities
+"""
diff --git a/osbuild/testutil/imports.py b/osbuild/testutil/imports.py
new file mode 100644
index 000000000..3fb14aeee
--- /dev/null
+++ b/osbuild/testutil/imports.py
@@ -0,0 +1,27 @@
+#!/usr/bin/python3
+"""
+Import related utilities
+"""
+import importlib
+from types import ModuleType
+
+
+def import_module_from_path(fullname, path: str) -> ModuleType:
+    """import_module_from_path imports the given path as a python module
+
+    This helper is useful when importing things that are not in the
+    import path or have invalid python import filenames, e.g. all
+    filenames in the stages/ dir of osbuild.
+
+    Keyword arguments:
+    fullname -- The absolute name of the module (can be arbitrary, used on in ModuleSpec.name)
+    path     -- The full path to the python file
+    """
+    loader = importlib.machinery.SourceFileLoader(fullname, path)
+    spec = importlib.util.spec_from_loader(loader.name, loader)
+    if spec is None:
+        # mypy warns that spec might be None so handle it
+        raise ImportError(f"cannot import {fullname} from {path}, got None as the spec")
+    mod = importlib.util.module_from_spec(spec)
+    loader.exec_module(mod)
+    return mod
diff --git a/test/mod/test_testutil_imports.py b/test/mod/test_testutil_imports.py
new file mode 100644
index 000000000..8b8e9a06f
--- /dev/null
+++ b/test/mod/test_testutil_imports.py
@@ -0,0 +1,17 @@
+#
+# Tests for the 'osbuild.util.testutil' module.
+#
+import os.path
+import tempfile
+
+import pytest
+
+from osbuild.testutil.imports import import_module_from_path
+
+
+canary = "import-went-okay"
+
+
+def test_import_module_from_path_happy():
+    mod = import_module_from_path("myself", __file__)
+    assert mod.canary == "import-went-okay"