Better handling of namespace validation to fix a number of issues

- Fixes a bug which allows for underscores at the beginning of namespaces: Fixes #1849
- Allows dots and dashes for newer Docker clients: Fixes #1188
- Has the UI display better messaging associated with namespace entry

test/test_util.py

@@ -4,12 +4,45 @@ import magic
 from itertools import islice
 from semantic_version import Version, Spec
 
-from util.validation import generate_valid_usernames
+from util.validation import generate_valid_usernames, validate_username
 from util.registry.generatorfile import GeneratorFile
 from util.registry.dockerver import docker_version
 from util import slash_join
 from _pyio import BufferedReader
 
+class TestUsernameValidation(unittest.TestCase):
+  def assertValid(self, username):
+    result, _ = validate_username(username)
+    self.assertTrue(result)
+
+  def assertInvalid(self, username):
+    result, _ = validate_username(username)
+    self.assertFalse(result)
+
+  def test_valid(self):
+    self.assertValid('jake')
+    self.assertValid('ja_ke')
+    self.assertValid('te-st')
+    self.assertValid('te.st')
+
+  def test_properlength(self):
+    self.assertValid('z' * 30)
+
+  def test_tooshort(self):
+    self.assertInvalid('j')
+    self.assertInvalid('ja')
+    self.assertInvalid('jk')
+
+  def test_toolong(self):
+    self.assertInvalid('z' * 31)
+
+  def test_invalids(self):
+    self.assertInvalid('_test')
+    self.assertInvalid('Test')
+    self.assertInvalid('hello world')
+    self.assertInvalid('te---st')
+
+
 class TestGeneratorFile(unittest.TestCase):
   def sample_generator(self):
     yield 'this'
@@ -128,6 +161,9 @@ class TestUsernameGenerator(unittest.TestCase):
     self.assert_generated_output('ja__', 'ja00')
     self.assert_generated_output('jake__', 'jake')
 
+  def test_starting_underscore(self):
+    self.assert_generated_output('_jake', 'jake')
+
   def test_short_names(self):
     self.assert_generated_output('a', 'a000')
     self.assert_generated_output('ab', 'ab00')