stages/vagrant: add virtualbox support

This adds support generating a virtualbox vagrant image. It differs from
libvirt by requiring an xml file and a vmdk image.

When the provider is set to libvirt it is required to pass a
`virtualbox` configuration section to this stage which must include the
mac address.

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

stages/test/test_vagrant.py

@@ -0,0 +1,41 @@
+#!/usr/bin/python3
+
+import pytest
+
+from osbuild import testutil
+
+STAGE_NAME = "org.osbuild.vagrant"
+
+
+# Prepare dataset containing good and bad API call parameters
+@pytest.mark.parametrize("test_data, expected_err", [
+    # Bad API parameters
+    ({}, "not valid under any of the given schemas"),
+    ({"provider": "none"}, "not valid under any of the given schemas"),
+    ({"provider": "virtualbox"}, "not valid under any of the given schemas"),
+    ({"provider": "virtualbox", "virtualbox": {}}, "not valid under any of the given schemas"),
+    ({"provider": "libvirt", "virtualbox": {"mac_address": "1"}}, "not valid under any of the given schemas"),
+    # Good API parameters
+    ({"provider": "libvirt"}, ""),
+    ({"provider": "virtualbox", "virtualbox": {"mac_address": "000000000000"}}, ""),
+])
+# This test validates only API calls using correct and incorrect queries
+def test_schema_validation_vagrant(stage_schema, test_data, expected_err):
+    test_input = {
+        "type": STAGE_NAME,
+        "devices": {
+            "device": {
+                "path": "some-path",
+            },
+        },
+        "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, f"err: {[e.as_dict() for e in res.errors]}"
+        testutil.assert_jsonschema_error_contains(res, expected_err)