Fix type hint on normalize prefix argument (#6008)

datadog_checks_base/datadog_checks/base/checks/base.py

@@ -626,12 +626,13 @@ def set_external_tags(self, external_tags):
             raise
 
     def convert_to_underscore_separated(self, name):
-        # type: (bytes) -> bytes
+        # type: (Union[str, bytes]) -> bytes
         """
         Convert from CamelCase to camel_case
         And substitute illegal metric characters
         """
-        metric_name = self.FIRST_CAP_RE.sub(br'\1_\2', ensure_bytes(name))
+        name = ensure_bytes(name)
+        metric_name = self.FIRST_CAP_RE.sub(br'\1_\2', name)
         metric_name = self.ALL_CAP_RE.sub(br'\1_\2', metric_name).lower()
         metric_name = self.METRIC_REPLACEMENT.sub(br'_', metric_name)
         return self.DOT_UNDERSCORE_CLEANUP.sub(br'.', metric_name).strip(b'_')
@@ -693,7 +694,7 @@ def _format_namespace(self, s, raw=False):
         return to_native_string(s)
 
     def normalize(self, metric, prefix=None, fix_case=False):
-        # type: (Union[str, bytes], bytes, bool) -> str
+        # type: (Union[str, bytes], Union[str, bytes], bool) -> str
         """
         Turn a metric into a well-formed metric name
         prefix.b.c

datadog_checks_base/datadog_checks/base/utils/common.py

@@ -7,7 +7,7 @@
 import re
 import warnings
 from decimal import ROUND_HALF_UP, Decimal
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, Text, Union
 
 from six import PY3, iteritems, text_type
 from six.moves.urllib.parse import urlparse
@@ -16,12 +16,14 @@
 
 
 def ensure_bytes(s):
+    # type: (Union[Text, bytes]) -> bytes
     if isinstance(s, text_type):
         s = s.encode('utf-8')
     return s
 
 
 def ensure_unicode(s):
+    # type: (Union[Text, bytes]) -> Text
     if isinstance(s, bytes):
         s = s.decode('utf-8')
     return s