test: move test_objectstore into module-tests

Move `test_objectstore` into the module-level tests. This allows us to
run it as part of `make test-module.

Make sure to properly guard it as root-only module.

.github/workflows/tests.yml

@@ -74,11 +74,6 @@ jobs:
           cd osbuild
           python3 -m unittest -v test.test_osbuild
 
-      - name: Run test_objectstore
-        run: |
-          cd osbuild
-          python3 -m unittest -v test.test_objectstore
-
   sample_validation:
     name: "sample validation"
     runs-on: ubuntu-latest

test/mod/test_objectstore.py

@@ -1,3 +1,7 @@
+#
+# Tests for the 'osbuild.objectstore' module.
+#
+
 import os
 import shutil
 import tempfile
@@ -5,8 +9,10 @@ import unittest
 
 from pathlib import Path
 from osbuild import objectstore
+from .. import test
 
 
+@unittest.skipUnless(test.TestBase.can_bind_mount(), "root-only")
 class TestObjectStore(unittest.TestCase):
 
     @classmethod
@@ -279,7 +285,3 @@ class TestObjectStore(unittest.TestCase):
             p = Path(f"{path}/osbuild-test-file")
             with self.assertRaises(OSError):
                 p.touch()
-
-
-if __name__ == "__main__":
-    unittest.main()

test/test.py

@@ -119,6 +119,52 @@ class TestBase(unittest.TestCase):
 
         return True
 
+    @staticmethod
+    def can_bind_mount() -> bool:
+        """Check Bind-Mount Capability
+
+        Test whether we can bind-mount file-system objects. If yes, return
+        `True`, otherwise return `False`.
+        """
+
+        with tempfile.TemporaryDirectory() as tmpdir:
+            original = os.path.join(tmpdir, "original")
+            mnt = os.path.join(tmpdir, "mnt")
+
+            with open(original, "w") as f:
+                f.write("foo")
+            with open(mnt, "w") as f:
+                f.write("bar")
+
+            try:
+                subprocess.run(
+                    [
+                        "mount",
+                        "--make-private",
+                        "-o",
+                        "bind,ro",
+                        original,
+                        mnt,
+                    ],
+                    stdin=subprocess.DEVNULL,
+                    stdout=subprocess.DEVNULL,
+                    stderr=subprocess.DEVNULL,
+                    check=True,
+                )
+                with open(mnt, "r") as f:
+                    assert f.read() == "foo"
+                return True
+            except subprocess.CalledProcessError:
+                return False
+            finally:
+                subprocess.run(
+                    ["umount", mnt],
+                    stdin=subprocess.DEVNULL,
+                    stdout=subprocess.DEVNULL,
+                    stderr=subprocess.DEVNULL,
+                    check=False,
+                )
+
     @staticmethod
     def have_rpm_ostree() -> bool:
         """Check rpm-ostree Availability