Add retrying of failed driver initialization (#249)

Fixes: #219

Pipfile

@@ -9,6 +9,9 @@ tox = "*"
 flake8 = "*"
 black = "*"
 pre-commit = "*"
+pytest-localserver = "*"
+pytest-xdist = "*"
+pytest-mock = "*"
 
 [packages]
 pytest-selenium = {editable = true,extras = ["appium"],path = "."}

docs/news.rst

@@ -10,6 +10,8 @@ Release Notes
 
 * Drop `PhantomJS` support
 
+* Add driver initialization retry
+
 
 1.17.0 (2019-07-13)
 -------------------

pytest_selenium/pytest_selenium.py

@@ -13,6 +13,7 @@
 from selenium import webdriver
 from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
 from selenium.webdriver.support.event_firing_webdriver import EventFiringWebDriver
+from tenacity import Retrying, stop_after_attempt, wait_exponential
 
 from .utils import CaseInsensitiveDict
 from . import drivers
@@ -195,7 +196,16 @@ def driver_path(request):
 @pytest.fixture
 def driver(request, driver_class, driver_kwargs):
     """Returns a WebDriver instance based on options and capabilities"""
-    driver = driver_class(**driver_kwargs)
+
+    retries = int(request.config.getini("max_driver_init_attempts"))
+    for retry in Retrying(
+        stop=stop_after_attempt(retries), wait=wait_exponential(), reraise=True
+    ):
+        with retry:
+            LOGGER.info(
+                f"Driver init, attempt {retry.retry_state.attempt_number}/{retries}"
+            )
+            driver = driver_class(**driver_kwargs)
 
     event_listener = request.config.getoption("event_listener")
     if event_listener is not None:
@@ -409,6 +419,11 @@ def pytest_addoption(parser):
         default=os.getenv("SAUCELABS_JOB_AUTH", "none"),
     )
 
+    parser.addini(
+        "max_driver_init_attempts",
+        help="Maximum number of driver initialization attempts",
+        default=3,
+    )
     group = parser.getgroup("selenium", "selenium")
     group._addoption(
         "--driver",

setup.py

@@ -16,6 +16,7 @@
         "pytest-variables>=1.5.0",
         "selenium>=3.0.0",
         "requests",
+        "tenacity>=6,<7",
     ],
     entry_points={
         "pytest11": [

testing/test_driver.py

@@ -4,8 +4,11 @@
 
 from functools import partial
 
+import pytest_selenium
 import pytest
 
+from pytest_selenium.utils import CaseInsensitiveDict
+
 pytestmark = pytest.mark.nondestructive
 
 
@@ -180,3 +183,58 @@ def test_pass(driver_kwargs):
     """
     )
     testdir.quick_qa("--driver", "Firefox", file_test, passed=1)
+
+
+def test_driver_retry_pass(testdir, mocker):
+    mocker.patch.dict(
+        pytest_selenium.SUPPORTED_DRIVERS,
+        CaseInsensitiveDict({"Firefox": mocker.MagicMock()}),
+    )
+    mock_retrying = mocker.spy(pytest_selenium.pytest_selenium, "Retrying")
+
+    file_test = testdir.makepyfile(
+        """
+        import pytest
+
+        @pytest.mark.nondestructive
+        def test_pass(driver):
+            assert driver
+    """
+    )
+
+    testdir.quick_qa("--driver", "Firefox", file_test, passed=1)
+    assert mock_retrying.spy_return.statistics["attempt_number"] == 1
+
+
+@pytest.mark.parametrize("max_num_attempts", [None, 2])
+def test_driver_retry_fail(testdir, mocker, max_num_attempts):
+    mocker.patch(
+        "pytest_selenium.webdriver.firefox.webdriver.FirefoxRemoteConnection",
+        side_effect=Exception("Connection Error"),
+    )
+    mocker.patch("pytest_selenium.webdriver.firefox.webdriver.Service")
+    mocker.patch("pytest_selenium.pytest_selenium.wait_exponential", return_value=0)
+    mock_retrying = mocker.spy(pytest_selenium.pytest_selenium, "Retrying")
+
+    default_attempts = 3
+    if max_num_attempts is not None:
+        testdir.makeini(
+            f"""
+            [pytest]
+            max_driver_init_attempts = {max_num_attempts}
+            """
+        )
+
+    file_test = testdir.makepyfile(
+        """
+        import pytest
+
+        @pytest.mark.nondestructive
+        def test_pass(driver):
+            assert True  # catch if this starts to pass
+        """
+    )
+
+    testdir.quick_qa("--driver", "Firefox", file_test, failed=1)
+    expected_attempts = max_num_attempts or default_attempts
+    assert mock_retrying.spy_return.statistics["attempt_number"] == expected_attempts

tox.ini

@@ -14,6 +14,7 @@ setenv =
 deps =
     pytest-localserver
     pytest-xdist
+    pytest-mock
 commands = pytest -n auto -v -r a --color=yes --html={envlogdir}/report.html --self-contained-html {posargs}
 
 [testenv:docs]