Implement push pre-check.

LP: #1610776

snapcraft/_store.py

@@ -409,11 +409,14 @@ def push(snap_filename, release_channels=None):
         raise FileNotFoundError(
             'The file {!r} does not exist.'.format(snap_filename))
 
-    logger.info('Uploading {}.'.format(snap_filename))
-
     snap_yaml = _get_data_from_snap_file(snap_filename)
     snap_name = snap_yaml['name']
     store = storeapi.StoreClient()
+
+    with _requires_login():
+        store.push_precheck(snap_name)
+
+    logger.info('Uploading {}.'.format(snap_filename))
     with _requires_login():
         tracker = store.upload(snap_name, snap_filename)
 

snapcraft/storeapi/__init__.py

@@ -185,6 +185,10 @@ def register(self, snap_name, is_private=False):
         return self._refresh_if_necessary(
             self.sca.register, snap_name, is_private, constants.DEFAULT_SERIES)
 
+    def push_precheck(self, snap_name):
+        return self._refresh_if_necessary(
+            self.sca.snap_push_precheck, snap_name)
+
     def push_snap_build(self, snap_id, snap_build):
         return self._refresh_if_necessary(
             self.sca.push_snap_build, snap_id, snap_build)
@@ -494,6 +498,20 @@ def register(self, snap_name, is_private, series):
         if not response.ok:
             raise errors.StoreRegistrationError(snap_name, response)
 
+    def snap_push_precheck(self, snap_name):
+        data = {
+            'name': snap_name,
+            'dry_run': True,
+        }
+        auth = _macaroon_auth(self.conf)
+        response = self.post(
+            'snap-push/', data=json.dumps(data),
+            headers={'Authorization': auth,
+                     'Content-Type': 'application/json',
+                     'Accept': 'application/json'})
+        if not response.ok:
+            raise errors.StorePushError(data['name'], response)
+
     def snap_push_metadata(self, snap_name, updown_data):
         data = {
             'name': snap_name,

snapcraft/tests/test_commands_push.py

@@ -30,7 +30,10 @@
 )
 from snapcraft.internal.cache._snap import _rewrite_snap_filename_with_revision
 from snapcraft.main import main
-from snapcraft.storeapi.errors import StoreUploadError
+from snapcraft.storeapi.errors import (
+    StorePushError,
+    StoreUploadError,
+)
 from snapcraft.tests import fixture_setup
 
 
@@ -45,6 +48,10 @@ def setUp(self):
         patcher.start()
         self.addCleanup(patcher.stop)
 
+        patcher = mock.patch('snapcraft.storeapi.StoreClient.push_precheck')
+        patcher.start()
+        self.addCleanup(patcher.stop)
+
     def test_push_without_snap_must_raise_exception(self):
         raised = self.assertRaises(
             docopt.DocoptExit,
@@ -101,6 +108,34 @@ def test_push_nonexisting_snap_must_raise_exception(self):
             SystemExit,
             main, ['push', 'test-unexisting-snap'])
 
+    def test_push_unregistered_snap_must_raise_exception(self):
+        self.useFixture(fixture_setup.FakeTerminal())
+
+        class MockResponse:
+            status_code = 404
+            error_list = [{'code': 'resource-not-found',
+                           'message': 'Snap not found for name=my-snap-name'}]
+
+        patcher = mock.patch.object(storeapi.StoreClient, 'push_precheck')
+        mock_precheck = patcher.start()
+        self.addCleanup(patcher.stop)
+        mock_precheck.side_effect = StorePushError(
+            'my-snap-name', MockResponse())
+
+        # Create a snap
+        main(['init'])
+        main(['snap'])
+        snap_file = glob.glob('*.snap')[0]
+
+        self.assertRaises(
+            SystemExit,
+            main, ['push', snap_file])
+
+        self.assertIn(
+            'Sorry, try `snapcraft register my-snap-name` '
+            'before pushing again.',
+            self.fake_logger.output)
+
     def test_push_with_updown_error(self):
         # We really don't know of a reason why this would fail
         # aside from a 5xx style error on the server.
@@ -265,6 +300,13 @@ class PushCommandDeltasTestCase(tests.TestCase):
         ('without deltas', dict(enable_deltas=False)),
     ]
 
+    def setUp(self):
+        super().setUp()
+
+        patcher = mock.patch('snapcraft.storeapi.StoreClient.push_precheck')
+        patcher.start()
+        self.addCleanup(patcher.stop)
+
     def test_push_revision_cached_with_experimental_deltas(self):
         self.useFixture(fixture_setup.FakeTerminal())
         if self.enable_deltas:
@@ -328,6 +370,10 @@ def test_push_revision_prune_snap_cache(self):
 
         snap_revision = 9
 
+        patcher = mock.patch('snapcraft.storeapi.StoreClient.push_precheck')
+        patcher.start()
+        self.addCleanup(patcher.stop)
+
         mock_tracker = mock.Mock(storeapi.StatusTracker)
         mock_tracker.track.return_value = {
             'code': 'ready_to_release',