diff --git a/tests/test_api/test_cerberus.py b/tests/test_api/test_cerberus.py
new file mode 100644
index 00000000..89c9210f
--- /dev/null
+++ b/tests/test_api/test_cerberus.py
@@ -0,0 +1,170 @@
+"""Test that what we feed to Cerberus actually works.
+
+This'll help us upgrade to new versions of Cerberus.
+"""
+
+import unittest
+from pillar.tests import AbstractPillarTest
+
+from bson import ObjectId
+
+
+class CerberusCanaryTest(unittest.TestCase):
+
+    def _canary_test(self, validator):
+        groups_schema = {'name': {'type': 'string', 'required': True}}
+
+        # On error, validate_schema() raises ValidationError
+        validator.validate_schema(groups_schema)
+
+        # On error, validate() returns False
+        self.assertTrue(validator.validate({'name': 'je moeder'}, groups_schema))
+        self.assertFalse(validator.validate({'je moeder': 'op je hoofd'}, groups_schema))
+
+    def test_canary(self):
+        import cerberus
+
+        validator = cerberus.Validator()
+        self._canary_test(validator)
+
+    def test_our_validator_simple(self):
+        from pillar.api import custom_field_validation
+
+        validator = custom_field_validation.ValidateCustomFields()
+        self._canary_test(validator)
+
+
+class ValidationTest(AbstractPillarTest):
+    def setUp(self):
+        super().setUp()
+
+        from pillar.api import custom_field_validation
+
+        self.validator = custom_field_validation.ValidateCustomFields()
+        self.user_id = ObjectId(8 * 'abc')
+        self.ensure_user_exists(self.user_id, 'Tést Üsâh')
+
+    def assertValid(self, document, schema):
+        with self.app.app_context():
+            is_valid = self.validator.validate(document, schema)
+        self.assertTrue(is_valid, f'errors: {self.validator.errors}')
+
+    def assertInvalid(self, document, schema):
+        with self.app.app_context():
+            is_valid = self.validator.validate(document, schema)
+        self.assertFalse(is_valid)
+
+
+class ProjectValidationTest(ValidationTest):
+
+    def test_empty(self):
+        from pillar.api.eve_settings import projects_schema
+        self.assertInvalid({}, projects_schema)
+
+    def test_simple_project(self):
+        from pillar.api.eve_settings import projects_schema
+
+        project = {
+            'name': 'Té Ærhüs',
+            'user': self.user_id,
+            'category': 'assets',
+            'is_private': False,
+            'status': 'published',
+        }
+
+        self.assertValid(project, projects_schema)
+
+    def test_with_node_types(self):
+        from pillar.api.eve_settings import projects_schema
+        from pillar.api import node_types
+
+        project = {
+            'name': 'Té Ærhüs',
+            'user': self.user_id,
+            'category': 'assets',
+            'is_private': False,
+            'status': 'published',
+            'node_types': [node_types.node_type_asset,
+                           node_types.node_type_comment]
+        }
+
+        self.assertValid(project, projects_schema)
+
+
+class NodeValidationTest(ValidationTest):
+    def setUp(self):
+        super().setUp()
+        self.pid, self.project = self.ensure_project_exists()
+
+    def test_empty(self):
+        from pillar.api.eve_settings import nodes_schema
+        self.assertInvalid({}, nodes_schema)
+
+    def test_asset(self):
+        from pillar.api.eve_settings import nodes_schema
+
+        file_id, _ = self.ensure_file_exists()
+
+        node = {
+            'name': '"The Harmless Prototype™"',
+            'project': self.pid,
+            'node_type': 'asset',
+            'properties': {
+                'status': 'published',
+                'content_type': 'image',
+                'file': file_id,
+            },
+            'user': self.user_id,
+            'short_code': 'ABC333',
+        }
+        self.assertValid(node, nodes_schema)
+
+    def test_asset_invalid_properties(self):
+        from pillar.api.eve_settings import nodes_schema
+
+        file_id, _ = self.ensure_file_exists()
+
+        node = {
+            'name': '"The Harmless Prototype™"',
+            'project': self.pid,
+            'node_type': 'asset',
+            'properties': {
+                'status': 'invalid-status',
+                'content_type': 'image',
+                'file': file_id,
+            },
+            'user': self.user_id,
+            'short_code': 'ABC333',
+        }
+        self.assertInvalid(node, nodes_schema)
+
+    def test_comment(self):
+        from pillar.api.eve_settings import nodes_schema
+
+        file_id, _ = self.ensure_file_exists()
+
+        node = {
+            'name': '"The Harmless Prototype™"',
+            'project': self.pid,
+            'node_type': 'asset',
+            'properties': {
+                'status': 'published',
+                'content_type': 'image',
+                'file': file_id,
+            },
+            'user': self.user_id,
+            'short_code': 'ABC333',
+        }
+        node_id = self.create_node(node)
+
+        comment = {
+            'name': 'comment on some node',
+            'project': self.pid,
+            'node_type': 'comment',
+            'properties': {
+                'content': 'this is a comment',
+                'status': 'published',
+            },
+            'parent': node_id,
+        }
+        self.assertValid(comment, nodes_schema)