boolean type strips space before converting

1 files changed, 7 insertions, 3 deletions

diff --git a/src/click/types.py b/src/click/types.py
index b7161d9..721c556 100644
--- a/src/click/types.py
+++ b/src/click/types.py
@@ -497,11 +497,15 @@ class BoolParamType(ParamType):
     def convert(self, value, param, ctx):
         if isinstance(value, bool):
             return bool(value)
-        value = value.lower()
-        if value in {"1", "true", "t", "yes", "y", "on"}:
+
+        norm = value.strip().lower()
+
+        if norm in {"1", "true", "t", "yes", "y", "on"}:
             return True
-        elif value in {"0", "false", "f", "no", "n", "off"}:
+
+        if norm in {"0", "false", "f", "no", "n", "off"}:
             return False
+
         self.fail(f"{value!r} is not a valid boolean value.", param, ctx)
 
     def __repr__(self):