Bring back the PR Refactor doctests + add CI to main (#23271)

* Revert "Revert "[Doctests] Refactor doctests + add CI" (#23245)"

This reverts commit 69ee46243c.

* try not expose HfDocTestParser

* move into testing_utils.py

* remove pytest install

---------

Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>

conftest.py

@@ -20,6 +20,10 @@ import sys
 import warnings
 from os.path import abspath, dirname, join
 
+import _pytest
+
+from transformers.testing_utils import HfDoctestModule, HfDocTestParser
+
 
 # allow having multiple repository checkouts and not needing to remember to rerun
 # 'pip install -e .[dev]' when switching between checkouts and running tests.
@@ -38,9 +42,7 @@ def pytest_configure(config):
     config.addinivalue_line(
         "markers", "is_pt_flax_cross_test: mark test to run only when PT and FLAX interactions are tested"
     )
-    config.addinivalue_line(
-        "markers", "is_pipeline_test: mark test to run only when pipelines are tested"
-    )
+    config.addinivalue_line("markers", "is_pipeline_test: mark test to run only when pipelines are tested")
     config.addinivalue_line("markers", "is_staging_test: mark test to run only in the staging environment")
     config.addinivalue_line("markers", "accelerate_tests: mark test that require accelerate")
     config.addinivalue_line("markers", "tool_tests: mark the tool tests that are run on their specific schedule")
@@ -67,7 +69,7 @@ def pytest_sessionfinish(session, exitstatus):
 
 
 # Doctest custom flag to ignore output.
-IGNORE_RESULT = doctest.register_optionflag('IGNORE_RESULT')
+IGNORE_RESULT = doctest.register_optionflag("IGNORE_RESULT")
 
 OutputChecker = doctest.OutputChecker
 
@@ -80,3 +82,5 @@ class CustomOutputChecker(OutputChecker):
 
 
 doctest.OutputChecker = CustomOutputChecker
+_pytest.doctest.DoctestModule = HfDoctestModule
+doctest.DocTestParser = HfDocTestParser