TST: Parametrize simple yield tests

xref pandas-dev#15341

Author: Elliott Sales de Andrade <[email protected]>

Closes pandas-dev#15406 from QuLogic/pytest-simple-yield and squashes the following commits:

b002752 [Elliott Sales de Andrade] TST: Set PYTHONHASHSEED so xdist doesn't break.
8368772 [Elliott Sales de Andrade] TST: Use fixtures for engine/parser where possible.
c6cd346 [Elliott Sales de Andrade] TST: Parametrize remaining simple yield tests.
47bf1a1 [Elliott Sales de Andrade] TST: Replace ENGINES_PARSERS by parametrize.

Author: QuLogic

ci/script_multi.sh

@@ -17,6 +17,12 @@ if [ -n "$LOCALE_OVERRIDE" ]; then
     python -c "$pycmd"
 fi
 
+# Workaround for pytest-xdist flaky collection order
+# https://github.com/pytest-dev/pytest/issues/920
+# https://github.com/pytest-dev/pytest/issues/1075
+export PYTHONHASHSEED=$(python -c 'import random; print(random.randint(1, 4294967295))')
+echo PYTHONHASHSEED=$PYTHONHASHSEED
+
 if [ "$BUILD_TEST" ]; then
     echo "We are not running pytest as this is simply a build test."
 elif [ "$COVERAGE" ]; then

pandas/tests/computation/test_compat.py

@@ -12,8 +12,6 @@
 import pandas.computation.expr as expr
 from pandas.computation import _MIN_NUMEXPR_VERSION
 
-ENGINES_PARSERS = list(product(_engines, expr._parsers))
-
 
 def test_compat():
     # test we have compat with our version of nu
@@ -30,12 +28,9 @@ def test_compat():
         pytest.skip("not testing numexpr version compat")
 
 
-def test_invalid_numexpr_version():
-    for engine, parser in ENGINES_PARSERS:
-        yield check_invalid_numexpr_version, engine, parser
-
-
-def check_invalid_numexpr_version(engine, parser):
+@pytest.mark.parametrize('engine', _engines)
+@pytest.mark.parametrize('parser', expr._parsers)
+def test_invalid_numexpr_version(engine, parser):
     def testit():
         a, b = 1, 2
         res = pd.eval('a + b', engine=engine, parser=parser)