utils: Tighten `parse_comma_separated_list()` contract further

Now that callers are ensuring that `value` is not `None`, we can further
tighten the contract and remove the conditional to account when `None`
is passed-in for `value`.

Additionally, add a new test vector to account for when an empty string
is passed in, which would fail `if no value`.

1 files changed, 1 insertions, 4 deletions

diff --git a/src/flake8/utils.py b/src/flake8/utils.py
index 619c83d..92fec71 100644
--- a/src/flake8/utils.py
+++ b/src/flake8/utils.py
@@ -24,7 +24,7 @@ string_types = (str, type(u""))
 
 
 def parse_comma_separated_list(value, regexp=COMMA_SEPARATED_LIST_RE):
-    # type: (Optional[str], Pattern[str]) -> List[str]
+    # type: (str, Pattern[str]) -> List[str]
     """Parse a comma-separated list.
 
     :param value:
@@ -41,9 +41,6 @@ def parse_comma_separated_list(value, regexp=COMMA_SEPARATED_LIST_RE):
     """
     assert isinstance(value, string_types), value  # nosec (for bandit)
 
-    if not value:
-        return []
-
     separated = regexp.split(value)
     item_gen = (item.strip() for item in separated)
     return [item for item in item_gen if item]