From 3d39af0db0dd25520bf11f7fc1d340a7d24a3971 Mon Sep 17 00:00:00 2001
From: Noah Negin-Ulster <noah.negin-ulster@tophatmonocle.com>
Date: Thu, 29 Dec 2022 15:02:19 -0500
Subject: [PATCH] fix: ensure all pytest options are serializable

---
 poetry.lock            | 38 +++++++++++++++++++++++++++++++++++++-
 pyproject.toml         |  1 +
 src/syrupy/__init__.py | 19 ++++++++++++++++---
 3 files changed, 54 insertions(+), 4 deletions(-)

diff --git a/poetry.lock b/poetry.lock
index d2cdaec3..eb3247f8 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -432,6 +432,21 @@ files = [
 [package.extras]
 test = ["pytest (>=6)"]
 
+[[package]]
+name = "execnet"
+version = "1.9.0"
+description = "execnet: rapid multi-Python deployment"
+category = "dev"
+optional = false
+python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
+files = [
+    {file = "execnet-1.9.0-py2.py3-none-any.whl", hash = "sha256:a295f7cc774947aac58dde7fdc85f4aa00c42adf5d8f5468fc630c1acf30a142"},
+    {file = "execnet-1.9.0.tar.gz", hash = "sha256:8f694f3ba9cc92cab508b152dcfe322153975c29bda272e2fd7f3f00f36e47c5"},
+]
+
+[package.extras]
+testing = ["pre-commit"]
+
 [[package]]
 name = "flake8"
 version = "6.0.0"
@@ -935,6 +950,27 @@ aspect = ["aspectlib"]
 elasticsearch = ["elasticsearch"]
 histogram = ["pygal", "pygaljs"]
 
+[[package]]
+name = "pytest-xdist"
+version = "3.1.0"
+description = "pytest xdist plugin for distributed testing, most importantly across multiple CPUs"
+category = "dev"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "pytest-xdist-3.1.0.tar.gz", hash = "sha256:40fdb8f3544921c5dfcd486ac080ce22870e71d82ced6d2e78fa97c2addd480c"},
+    {file = "pytest_xdist-3.1.0-py3-none-any.whl", hash = "sha256:70a76f191d8a1d2d6be69fc440cdf85f3e4c03c08b520fd5dc5d338d6cf07d89"},
+]
+
+[package.dependencies]
+execnet = ">=1.1"
+pytest = ">=6.2.0"
+
+[package.extras]
+psutil = ["psutil (>=3.0)"]
+setproctitle = ["setproctitle"]
+testing = ["filelock"]
+
 [[package]]
 name = "pywin32-ctypes"
 version = "0.2.0"
@@ -1213,4 +1249,4 @@ testing = ["flake8 (<5)", "func-timeout", "jaraco.functools", "jaraco.itertools"
 [metadata]
 lock-version = "2.0"
 python-versions = '>=3.8.1,<4'
-content-hash = "e88747c14dd2913f472de3559d5fbd7577cc49b4e50ea5e13d5c077b3bd3ee05"
+content-hash = "145cf99a770f02939511a83b6744fb923c602848c52d6d364d7283e6219ee3bb"
diff --git a/pyproject.toml b/pyproject.toml
index d425fc13..ad26792b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -36,6 +36,7 @@ codecov = '^2.1.12'
 invoke = '^1.7.3'
 coverage = { version = '^6.5.0', extras = ['toml'] }
 pytest-benchmark = '^4.0.0'
+pytest-xdist = '^3.1.0'
 
 [tool.poetry.group.dev.dependencies]
 isort = '^5.10.1'
diff --git a/src/syrupy/__init__.py b/src/syrupy/__init__.py
index 744bb1cd..3e4ef5d9 100644
--- a/src/syrupy/__init__.py
+++ b/src/syrupy/__init__.py
@@ -1,5 +1,6 @@
 import argparse
 import sys
+from functools import lru_cache
 from gettext import gettext
 from typing import (
     Any,
@@ -30,13 +31,21 @@
 _syrupy: Optional["SnapshotSession"] = None
 
 
-def __default_extension_option(value: str) -> Any:
+@lru_cache
+def __import_extension(value: Optional[str]) -> Any:
+    if not value:
+        return DEFAULT_EXTENSION
     try:
         return import_module_member(value)
     except FailedToLoadModuleMember as e:
         raise argparse.ArgumentTypeError(e)
 
 
+def __default_extension_option(value: Optional[str]) -> Any:
+    __import_extension(value)
+    return value
+
+
 def pytest_addoption(parser: Any) -> None:
     """
     Exposes snapshot plugin configuration to pytest.
@@ -64,13 +73,17 @@ def pytest_addoption(parser: Any) -> None:
         dest="include_snapshot_details",
         help="Include details of unused snapshots in the final report",
     )
+
+    # We lazy evaluate the default extension since pytest-xdist requires
+    # all pytest options to be serializable.
     group.addoption(
         "--snapshot-default-extension",
         type=__default_extension_option,
-        default=DEFAULT_EXTENSION,
+        default=None,
         dest="default_extension",
         help="Specify the default snapshot extension",
     )
+
     group.addoption(
         "--snapshot-no-colors",
         action="store_true",
@@ -175,7 +188,7 @@ def pytest_terminal_summary(
 def snapshot(request: Any) -> "SnapshotAssertion":
     return SnapshotAssertion(
         update_snapshots=request.config.option.update_snapshots,
-        extension_class=request.config.option.default_extension,
+        extension_class=__import_extension(request.config.option.default_extension),
         test_location=PyTestLocation(request.node),
         session=request.session.config._syrupy,
     )