stages/wsl-distribution: stage to write wsl config

This is a new stage to be able to write a (subset) of relevant keys into
the `wsl-distribution` configuration file.

The file, and these options, are necessary for the enablement of fancy
logos and experiences in WSL2.

Signed-off-by: Simon de Vlieger <supakeen@redhat.com>

stages/test/test_wsl_distribution_conf.py

@@ -0,0 +1,80 @@
+#!/usr/bin/python3
+
+import pytest
+
+from osbuild import testutil
+
+STAGE_NAME = "org.osbuild.wsl-distribution.conf"
+
+
+@pytest.mark.parametrize("test_data,expected_err", [
+    # bad
+    ({"oobe": "must-be-object"}, "'must-be-object' is not of type 'object'"),
+    ({"shortcut": "must-be-object"}, "'must-be-object' is not of type 'object'"),
+    ({"shortcut": {"enabled": 1}}, "1 is not of type 'boolean'"),
+    ({"oobe": {"default_uid": True}}, "True is not of type 'integer'"),
+    # good
+    ({
+        "oobe":
+        {
+            "default_uid": 1000,
+            "default_name": "RedHatEnterpriseLinux-10.0",
+        },
+        "shortcut":
+        {
+            "enabled": True,
+            "icon": "/usr/share/pixmaps/fedora-logo.ico",
+        }
+    }, "")
+])
+def test_wsl_distribution_conf_schema_validation(stage_schema, test_data, expected_err):
+    test_input = {
+        "type": STAGE_NAME,
+        "options": {
+        }
+    }
+    test_input["options"].update(test_data)
+    res = stage_schema.validate(test_input)
+
+    if expected_err == "":
+        assert res.valid is True, f"err: {[e.as_dict() for e in res.errors]}"
+    else:
+        assert res.valid is False
+        testutil.assert_jsonschema_error_contains(res, expected_err, expected_num_errs=1)
+
+
+def test_wsl_distribution_conf_writes_file(tmp_path, stage_module):
+    treepath = tmp_path / "tree"
+
+    etcpath = treepath / "etc"
+    etcpath.mkdir(parents=True, exist_ok=True)
+
+    confpath = "wsl-distribution.conf"
+
+    fullpath = etcpath / confpath
+
+    options = {
+        "oobe": {
+            "default_name": "RedHatEnterpriseLinux-10.0",
+            "default_uid": 1000,
+        },
+        "shortcut": {
+            "enabled": True,
+            "icon": "/usr/share/pixmaps/fedora-logo.ico",
+        }
+    }
+
+    stage_module.main(treepath, options)
+
+    assert fullpath.exists()
+
+    confdata = fullpath.read_text()
+
+    assert confdata == """\
+[oobe]
+defaultUid = 1000
+defaultName = RedHatEnterpriseLinux-10.0
+
+[shortcut]
+enabled = true
+icon = /usr/share/pixmaps/fedora-logo.ico"""