fail verify_name_characters for blank name

lbrynet/metadata/Metadata.py

@@ -8,6 +8,7 @@ NAME_ALLOWED_CHARSET = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0987
 
 
 def verify_name_characters(name):
+    assert len(name) > 0, "Empty uri"
     for c in name:
         assert c in NAME_ALLOWED_CHARSET, "Invalid character"
     return True

tests/unit/core/test_Metadata.py

@@ -2,7 +2,21 @@ from lbrynet.metadata import Metadata
 from twisted.trial import unittest
 from jsonschema import ValidationError
 
+
 class MetadataTest(unittest.TestCase):
+    def test_name_error_if_blank(self):
+        with self.assertRaises(AssertionError):
+            Metadata.verify_name_characters("")
+
+    def test_name_error_if_contains_bad_chrs(self):
+        with self.assertRaises(AssertionError):
+            Metadata.verify_name_characters("wu tang")
+        with self.assertRaises(AssertionError):
+            Metadata.verify_name_characters("$wutang")
+        with self.assertRaises(AssertionError):
+            Metadata.verify_name_characters("#wutang")
+
+
     def test_validation_error_if_no_metadata(self):
         metadata = {}
         with self.assertRaises(ValidationError):