From afc610ece2f8db0c21a77dc9b0e8d8f1c0811c83 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Thu, 9 Nov 2023 14:53:38 +0100
Subject: [PATCH 1/2] gh-111881: Import doctest lazily in libregrtest

In most cases, doctest is not needed. So don't always import it at
startup.
---
 Lib/test/libregrtest/single.py | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/Lib/test/libregrtest/single.py b/Lib/test/libregrtest/single.py
index ad75ef54a8c3f8..9c89e600ba802f 100644
--- a/Lib/test/libregrtest/single.py
+++ b/Lib/test/libregrtest/single.py
@@ -1,4 +1,3 @@
-import doctest
 import faulthandler
 import gc
 import importlib
@@ -94,17 +93,20 @@ def regrtest_runner(result: TestResult, test_func, runtests: RunTests) -> None:
 
     stats: TestStats | None
 
-    match test_result:
-        case TestStats():
-            stats = test_result
-        case unittest.TestResult():
-            stats = TestStats.from_unittest(test_result)
-        case doctest.TestResults():
+    if isinstance(test_result, TestStats):
+        stats = test_result
+    elif isinstance(test_result, unittest.TestResult):
+        stats = TestStats.from_unittest(test_result)
+    elif test_result is None:
+        print_warning(f"{result.test_name} test runner returned None: {test_func}")
+        stats = None
+    else:
+        # Don't import doctest at top level since only few tests return
+        # a doctest.TestResult instance.
+        import doctest
+        if isinstance(test_result, doctest.TestResults):
             stats = TestStats.from_doctest(test_result)
-        case None:
-            print_warning(f"{result.test_name} test runner returned None: {test_func}")
-            stats = None
-        case _:
+        else:
             print_warning(f"Unknown test result type: {type(test_result)}")
             stats = None
 

From 0e9d0da97c168f0c8f6c8e79fbac58e12812942c Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Thu, 9 Nov 2023 15:33:30 +0100
Subject: [PATCH 2/2] Address Alex's review: keep match/case

---
 Lib/test/libregrtest/single.py | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/Lib/test/libregrtest/single.py b/Lib/test/libregrtest/single.py
index 9c89e600ba802f..5c7bc7d40fb394 100644
--- a/Lib/test/libregrtest/single.py
+++ b/Lib/test/libregrtest/single.py
@@ -93,22 +93,23 @@ def regrtest_runner(result: TestResult, test_func, runtests: RunTests) -> None:
 
     stats: TestStats | None
 
-    if isinstance(test_result, TestStats):
-        stats = test_result
-    elif isinstance(test_result, unittest.TestResult):
-        stats = TestStats.from_unittest(test_result)
-    elif test_result is None:
-        print_warning(f"{result.test_name} test runner returned None: {test_func}")
-        stats = None
-    else:
-        # Don't import doctest at top level since only few tests return
-        # a doctest.TestResult instance.
-        import doctest
-        if isinstance(test_result, doctest.TestResults):
-            stats = TestStats.from_doctest(test_result)
-        else:
-            print_warning(f"Unknown test result type: {type(test_result)}")
+    match test_result:
+        case TestStats():
+            stats = test_result
+        case unittest.TestResult():
+            stats = TestStats.from_unittest(test_result)
+        case None:
+            print_warning(f"{result.test_name} test runner returned None: {test_func}")
             stats = None
+        case _:
+            # Don't import doctest at top level since only few tests return
+            # a doctest.TestResult instance.
+            import doctest
+            if isinstance(test_result, doctest.TestResults):
+                stats = TestStats.from_doctest(test_result)
+            else:
+                print_warning(f"Unknown test result type: {type(test_result)}")
+                stats = None
 
     result.stats = stats