SignImage: accept archive_dir field, send to docker image

BUG=b:296086340
TEST=run_tests

Change-Id: Ic7afd74890b5669ca81ad12e236db93d497e77d3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4896770
Reviewed-by: Madeleine Hardt <hardtmad@google.com>
Commit-Queue: Jack Neus <jackneus@google.com>
Tested-by: Jack Neus <jackneus@google.com>
Auto-Submit: Jack Neus <jackneus@google.com>
diff --git a/api/controller/image_unittest.py b/api/controller/image_unittest.py
index 0da766a..b14ed7a 100644
--- a/api/controller/image_unittest.py
+++ b/api/controller/image_unittest.py
@@ -792,18 +792,21 @@
         self.assertEqual(rc, controller.RETURN_CODE_COMPLETED_UNSUCCESSFULLY)
 
 
-class SignImageTest(cros_test_lib.MockTestCase, api_config.ApiConfigMixin):
+class SignImageTest(
+    cros_test_lib.MockTempDirTestCase, api_config.ApiConfigMixin
+):
     """Sign image test."""
 
     def testValidateOnly(self):
         """Check that a validate only call does not execute any logic."""
         req = image_pb2.SignImageRequest(
+            archive_dir=str(self.tempdir),
             result_path=common_pb2.ResultPath(
                 path=common_pb2.Path(
                     path="/path/to/outside",
                     location=common_pb2.Path.OUTSIDE,
                 )
-            )
+            ),
         )
         resp = image_pb2.SignImageResponse()
         rc = image_controller.SignImage(req, resp, self.validate_only_config)