use pytest-xdist to speed up kokoro.

Author: ChanchalKumarMaji

oss_scripts/oss_tests.sh

@@ -39,6 +39,7 @@ TF2_IGNORE=$(for test in $TF2_IGNORE_TESTS; do echo "--ignore=$test "; done)
 #   enable_eager_execution calls set global state and pytest runs all the tests
 #   in the same process.
 pytest \
+  -n auto \
   --disable-warnings \
   $TF2_IGNORE \
   --ignore="tensorflow_datasets/testing/test_utils.py" \

setup.py

@@ -61,6 +61,7 @@
     # 'csiphash',  # https://github.com/tensorflow/datasets/issues/737
     'jupyter',
     'pytest',
+    'pytest-xdist',
 ]
 
 if sys.version_info.major == 3: