python: small optimization in PyCollector.collect()

Inline `_makeitem()` so that `self.ihook` (which is moderately
expensive) can be called only once.

Note: the renamed test "test_makeitem_non_underscore" (added in 9ac4faf (2009))
was broken since ee2f292 (2010), and was not adjusted for 1d7c718 (2012) then.
(Ref: pytest-dev#7671 (comment))

Co-authored-by: Daniel Hahler <[email protected]>

(cherry picked from / based on commit daca174)

Author: bluetech

src/_pytest/python.py

@@ -378,6 +378,7 @@ def collect(self):
             dicts.append(basecls.__dict__)
         seen = set()
         values = []
+        ihook = self.ihook
         for dic in dicts:
             # Note: seems like the dict can change during iteration -
             # be careful not to remove the list() without consideration.
@@ -388,12 +389,15 @@ def collect(self):
                 if name in seen:
                     continue
                 seen.add(name)
-                res = self._makeitem(name, obj)
+                res = ihook.pytest_pycollect_makeitem(
+                    collector=self, name=name, obj=obj
+                )
                 if res is None:
                     continue
-                if not isinstance(res, list):
-                    res = [res]
-                values.extend(res)
+                elif isinstance(res, list):
+                    values.extend(res)
+                else:
+                    values.append(res)
 
         def sort_key(item):
             fspath, lineno, _ = item.reportinfo()
@@ -402,10 +406,6 @@ def sort_key(item):
         values.sort(key=sort_key)
         return values
 
-    def _makeitem(self, name, obj):
-        # assert self.ihook.fspath == self.fspath, self
-        return self.ihook.pytest_pycollect_makeitem(collector=self, name=name, obj=obj)
-
     def _genfunctions(self, name, funcobj):
         module = self.getparent(Module).obj
         clscol = self.getparent(Class)

testing/python/collect.py

@@ -4,9 +4,13 @@
 
 import _pytest._code
 import pytest
+from _pytest.compat import TYPE_CHECKING
 from _pytest.config import ExitCode
 from _pytest.nodes import Collector
 
+if TYPE_CHECKING:
+    from _pytest.pytester import Testdir
+
 
 class TestModule:
     def test_failing_import(self, testdir):
@@ -845,14 +849,20 @@ def pytest_pycollect_makeitem(collector, name, obj):
         result = testdir.runpytest("--collect-only")
         result.stdout.fnmatch_lines(["*MyFunction*some*"])
 
-    def test_makeitem_non_underscore(self, testdir, monkeypatch):
-        modcol = testdir.getmodulecol("def _hello(): pass")
+    def test_makeitem_non_dunder(self, testdir: "Testdir") -> None:
+        modcol = testdir.getmodulecol(
+            """
+            def _hello(): pass
+            def __world(): pass
+            """
+        )
         values = []
-        monkeypatch.setattr(
-            pytest.Module, "_makeitem", lambda self, name, obj: values.append(name)
+        testdir.monkeypatch.setattr(
+            modcol.ihook, "pytest_pycollect_makeitem",
+            lambda collector, name, obj: values.append(name)
         )
-        values = modcol.collect()
-        assert "_hello" not in values
+        modcol.collect()
+        assert values == ["_hello"]
 
     def test_issue2369_collect_module_fileext(self, testdir):
         """Ensure we can collect files with weird file extensions as Python