gh-86275: improve Hypothesis configuration for CI and local runs (#104468)

Lib/test/support/hypothesis_helper.py

@@ -1,4 +1,35 @@
+import os
+
 try:
     import hypothesis
 except ImportError:
     from . import _hypothesis_stubs as hypothesis
+else:
+    # When using the real Hypothesis, we'll configure it to ignore occasional
+    # slow tests (avoiding flakiness from random VM slowness in CI).
+    hypothesis.settings.register_profile(
+        "slow-is-ok",
+        deadline=None,
+        suppress_health_check=[hypothesis.HealthCheck.too_slow],
+    )
+    hypothesis.settings.load_profile("slow-is-ok")
+
+    # For local development, we'll write to the default on-local-disk database
+    # of failing examples, and also use a pull-through cache to automatically
+    # replay any failing examples discovered in CI.  For details on how this
+    # works, see https://hypothesis.readthedocs.io/en/latest/database.html
+    if "CI" not in os.environ:
+        from hypothesis.database import (
+            GitHubArtifactDatabase,
+            MultiplexedDatabase,
+            ReadOnlyDatabase,
+        )
+
+        hypothesis.settings.register_profile(
+            "cpython-local-dev",
+            database=MultiplexedDatabase(
+                hypothesis.settings.default.database,
+                ReadOnlyDatabase(GitHubArtifactDatabase("python", "cpython")),
+            ),
+        )
+        hypothesis.settings.load_profile("cpython-local-dev")