Import packaging package lazily

Author: bluetech

src/_pytest/config/__init__.py

@@ -23,7 +23,6 @@
 
 import attr
 import py
-from packaging.version import Version
 from pluggy import HookimplMarker
 from pluggy import HookspecMarker
 from pluggy import PluginManager
@@ -1059,6 +1058,9 @@ def _checkversion(self):
 
         minver = self.inicfg.get("minversion", None)
         if minver:
+            # Imported lazily to improve start-up time.
+            from packaging.version import Version
+
             if Version(minver) > Version(pytest.__version__):
                 raise pytest.UsageError(
                     "%s:%d: requires pytest-%s, actual pytest-%s'"

src/_pytest/outcomes.py

@@ -9,8 +9,6 @@
 from typing import Optional
 from typing import TypeVar
 
-from packaging.version import Version
-
 TYPE_CHECKING = False  # avoid circular import through compat
 
 if TYPE_CHECKING:
@@ -217,6 +215,9 @@ def importorskip(
         return mod
     verattr = getattr(mod, "__version__", None)
     if minversion is not None:
+        # Imported lazily to improve start-up time.
+        from packaging.version import Version
+
         if verattr is None or Version(verattr) < Version(minversion):
             raise Skipped(
                 "module %r has __version__ %r, required is: %r"