Only test the files impacted by changes in the diff (#12644)

* Base test

* More test

* Fix mistake

* Add a docstring change

* Add doc ignore

* Add changes

* Add recursive dep search

* Add recursive dep search

* save

* Finalize test mapping

* Fix bug

* Print prettier

* Ignore comments and empty lines

* Make script runnable from anywhere

* Need dev install

* Like that

* Adapt

* Add as artifact

* Try on torch tests

* Fix yaml error

* Install GitPython

* Apply everywhere

* Be more defensive

* Revert to all tests if something is wrong

* Install GitPython

* Test if there are tests before launching.

* Fixes

* Fixes

* Fixes

* Fixes

* Bash syntax is horrible

* Be less stupid

* Try differently

* Typo

* Typo

* Typo

* Style

* Better name

* Escape quotes

* Ignore black unhelpful re-formatting

* Not a docstring

* Deal with inits in dependency map

* Run all tests once PR is merged.

* Add last job

* Apply suggestions from code review

Co-authored-by: Stas Bekman <stas00@users.noreply.github.com>

* Stronger dependencies gather

* Ignore empty lines too!

* Clean up

* Fix quality

Co-authored-by: Stas Bekman <stas00@users.noreply.github.com>

.circleci/config.yml

@@ -86,7 +86,13 @@ jobs:
                 key: v0.4-{{ checksum "setup.py" }}
                 paths:
                     - '~/.cache/pip'
-            - run: python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_torch_and_tf ./tests/ -m is_pt_tf_cross_test --durations=0 | tee tests_output.txt
+            - run: python utils/tests_fetcher.py | tee test_preparation.txt
+            - store_artifacts:
+                  path: ~/transformers/test_preparation.txt
+            - run: |
+                  if [ -f test_list.txt ]; then
+                    python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_torch_and_tf $(cat test_list.txt) -m is_pt_tf_cross_test --durations=0 | tee tests_output.txt
+                  fi
             - store_artifacts:
                   path: ~/transformers/tests_output.txt
             - store_artifacts:
@@ -116,7 +122,13 @@ jobs:
                 key: v0.4-{{ checksum "setup.py" }}
                 paths:
                     - '~/.cache/pip'
-            - run: python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_torch_and_flax ./tests/ -m is_pt_flax_cross_test --durations=0 | tee tests_output.txt
+            - run: python utils/tests_fetcher.py | tee test_preparation.txt
+            - store_artifacts:
+                  path: ~/transformers/test_preparation.txt
+            - run: |
+                  if [ -f test_list.txt ]; then
+                    python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_torch_and_flax $(cat test_list.txt) -m is_pt_flax_cross_test --durations=0 | tee tests_output.txt
+                  fi
             - store_artifacts:
                   path: ~/transformers/tests_output.txt
             - store_artifacts:
@@ -145,7 +157,13 @@ jobs:
                   key: v0.4-torch-{{ checksum "setup.py" }}
                   paths:
                       - '~/.cache/pip'
-            - run: python -m pytest -n 3 --dist=loadfile -s --make-reports=tests_torch ./tests/ | tee tests_output.txt
+            - run: python utils/tests_fetcher.py | tee test_preparation.txt
+            - store_artifacts:
+                  path: ~/transformers/test_preparation.txt
+            - run: |
+                  if [ -f test_list.txt ]; then
+                    python -m pytest -n 3 --dist=loadfile -s --make-reports=tests_torch $(cat test_list.txt) | tee tests_output.txt
+                  fi
             - store_artifacts:
                   path: ~/transformers/tests_output.txt
             - store_artifacts:
@@ -172,7 +190,13 @@ jobs:
                   key: v0.4-tf-{{ checksum "setup.py" }}
                   paths:
                       - '~/.cache/pip'
-            - run: python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_tf ./tests/ | tee tests_output.txt
+            - run: python utils/tests_fetcher.py | tee test_preparation.txt
+            - store_artifacts:
+                  path: ~/transformers/test_preparation.txt
+            - run: |
+                  if [ -f test_list.txt ]; then
+                    python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_tf $(cat test_list.txt) | tee tests_output.txt
+                  fi
             - store_artifacts:
                   path: ~/transformers/tests_output.txt
             - store_artifacts:
@@ -199,7 +223,13 @@ jobs:
                   key: v0.4-flax-{{ checksum "setup.py" }}
                   paths:
                       - '~/.cache/pip'
-            - run: python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_flax ./tests/ | tee tests_output.txt
+            - run: python utils/tests_fetcher.py | tee test_preparation.txt
+            - store_artifacts:
+                  path: ~/transformers/test_preparation.txt
+            - run: |
+                  if [ -f test_list.txt ]; then
+                    python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_flax $(cat test_list.txt) | tee tests_output.txt
+                  fi
             - store_artifacts:
                   path: ~/transformers/tests_output.txt
             - store_artifacts:
@@ -229,7 +259,13 @@ jobs:
                   key: v0.4-torch-{{ checksum "setup.py" }}
                   paths:
                       - '~/.cache/pip'
-            - run: python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_pipelines_torch -m is_pipeline_test ./tests/ | tee tests_output.txt
+            - run: python utils/tests_fetcher.py | tee test_preparation.txt
+            - store_artifacts:
+                  path: ~/transformers/test_preparation.txt
+            - run: |
+                  if [ -f test_list.txt ]; then
+                    python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_pipelines_torch -m is_pipeline_test $(cat test_list.txt) | tee tests_output.txt
+                  fi
             - store_artifacts:
                   path: ~/transformers/tests_output.txt
             - store_artifacts:
@@ -257,7 +293,13 @@ jobs:
                   key: v0.4-tf-{{ checksum "setup.py" }}
                   paths:
                       - '~/.cache/pip'
-            - run: python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_pipelines_tf ./tests/ -m is_pipeline_test | tee tests_output.txt
+            - run: python utils/tests_fetcher.py | tee test_preparation.txt
+            - store_artifacts:
+                  path: ~/transformers/test_preparation.txt
+            - run: |
+                  if [ -f test_list.txt ]; then
+                    python -m pytest -n 8 --dist=loadfile -rA -s --make-reports=tests_pipelines_tf $(cat test_list.txt) -m is_pipeline_test | tee tests_output.txt
+                  fi
             - store_artifacts:
                   path: ~/transformers/tests_output.txt
             - store_artifacts:
@@ -283,7 +325,10 @@ jobs:
                   key: v0.4-custom_tokenizers-{{ checksum "setup.py" }}
                   paths:
                       - '~/.cache/pip'
-            - run: python -m pytest -s --make-reports=tests_custom_tokenizers ./tests/test_tokenization_bert_japanese.py | tee tests_output.txt
+            - run: |
+                  if [ -f test_list.txt ]; then
+                    python -m pytest -s --make-reports=tests_custom_tokenizers ./tests/test_tokenization_bert_japanese.py | tee tests_output.txt
+                  fi
             - store_artifacts:
                   path: ~/transformers/tests_output.txt
             - store_artifacts:
@@ -311,7 +356,13 @@ jobs:
                   key: v0.4-torch_examples-{{ checksum "setup.py" }}
                   paths:
                       - '~/.cache/pip'
-            - run: TRANSFORMERS_IS_CI=1 python -m pytest -n 8 --dist=loadfile -s --make-reports=examples_torch ./examples/pytorch/ | tee examples_output.txt
+            - run: python utils/tests_fetcher.py | tee test_preparation.txt
+            - store_artifacts:
+                  path: ~/transformers/test_preparation.txt
+            - run: |
+                  if [ -f test_list.txt ]; then
+                    TRANSFORMERS_IS_CI=1 python -m pytest -n 8 --dist=loadfile -s --make-reports=examples_torch ./examples/pytorch/ | tee examples_output.txt
+                  fi
             - store_artifacts:
                   path: ~/transformers/examples_output.txt
             - store_artifacts:
@@ -343,7 +394,13 @@ jobs:
                   key: v0.4-hub-{{ checksum "setup.py" }}
                   paths:
                       - '~/.cache/pip'
-            - run: python -m pytest -sv ./tests/ -m is_staging_test
+            - run: python utils/tests_fetcher.py | tee test_preparation.txt
+            - store_artifacts:
+                  path: ~/transformers/test_preparation.txt
+            - run: |
+                  if [ -f test_list.txt ]; then
+                    python -m pytest -sv $(cat test_list.txt) -m is_staging_test
+                  fi
 
     run_tests_onnxruntime:
         working_directory: ~/transformers
@@ -366,7 +423,13 @@ jobs:
                   key: v0.4-onnx-{{ checksum "setup.py" }}
                   paths:
                       - '~/.cache/pip'
-            - run: python -m pytest -n 1 --dist=loadfile -s --make-reports=tests_torch ./tests/* -k onnx | tee tests_output.txt
+            - run: python utils/tests_fetcher.py | tee test_preparation.txt
+            - store_artifacts:
+                  path: ~/transformers/test_preparation.txt
+            - run: |
+                  if [ -f test_list.txt ]; then
+                    python -m pytest -n 1 --dist=loadfile -s --make-reports=tests_torch $(cat test_list.txt) -k onnx | tee tests_output.txt
+                  fi
             - store_artifacts:
                   path: ~/transformers/tests_output.txt
             - store_artifacts:
@@ -431,7 +494,7 @@ jobs:
                       - v0.4-code_quality-{{ checksum "setup.py" }}
                       - v0.4-{{ checksum "setup.py" }}
             - run: pip install --upgrade pip
-            - run: pip install isort
+            - run: pip install isort GitPython
             - run: pip install .[all,quality]
             - save_cache:
                   key: v0.4-code_quality-{{ checksum "setup.py" }}
@@ -448,6 +511,7 @@ jobs:
             - run: python utils/check_repo.py
             - run: python utils/check_inits.py
             - run: make deps_table_check_updated
+            - run: python utils/tests_fetcher.py --sanity_check
 
     check_repository_consistency:
         working_directory: ~/transformers

Makefile

@@ -40,6 +40,7 @@ extra_quality_checks:
 	python utils/check_dummies.py
 	python utils/check_repo.py
 	python utils/check_inits.py
+	python utils/tests_fetcher.py --sanity_check
 
 # this target runs checks on all files
 quality:

setup.py

@@ -100,6 +100,7 @@ _deps = [
     "flake8>=3.8.3",
     "flax>=0.3.4",
     "fugashi>=1.0",
+    "GitPython",
     "huggingface-hub==0.0.12",
     "importlib_metadata",
     "ipadic>=1.0.0,<2.0",
@@ -259,7 +260,7 @@ extras["codecarbon"] = deps_list("codecarbon")
 extras["sentencepiece"] = deps_list("sentencepiece", "protobuf")
 extras["testing"] = (
     deps_list(
-        "pytest", "pytest-xdist", "timeout-decorator", "parameterized", "psutil", "datasets", "pytest-timeout", "black", "sacrebleu", "rouge-score", "nltk"
+        "pytest", "pytest-xdist", "timeout-decorator", "parameterized", "psutil", "datasets", "pytest-timeout", "black", "sacrebleu", "rouge-score", "nltk", "GitPython"
     )
     + extras["retrieval"]
     + extras["modelcreation"]

src/transformers/dependency_versions_table.py

@@ -17,6 +17,7 @@ deps = {
     "flake8": "flake8>=3.8.3",
     "flax": "flax>=0.3.4",
     "fugashi": "fugashi>=1.0",
+    "GitPython": "GitPython",
     "huggingface-hub": "huggingface-hub==0.0.12",
     "importlib_metadata": "importlib_metadata",
     "ipadic": "ipadic>=1.0.0,<2.0",

tests/conftest.py

@@ -53,3 +53,9 @@ def pytest_terminal_summary(terminalreporter):
     make_reports = terminalreporter.config.getoption("--make-reports")
     if make_reports:
         pytest_terminal_summary_main(terminalreporter, id=make_reports)
+
+
+def pytest_sessionfinish(session, exitstatus):
+    # If no tests are collected, pytest exists with code 5, which makes the CI fail.
+    if exitstatus == 5:
+        session.exitstatus = 0

utils/style_doc.py

@@ -489,12 +489,14 @@ def style_file_docstrings(code_file, max_len=119, check_only=False):
     """Style all docstrings in `code_file` to `max_len`."""
     with open(code_file, "r", encoding="utf-8", newline="\n") as f:
         code = f.read()
-    splits = code.split('"""')
+    # fmt: off
+    splits = code.split('\"\"\"')
     splits = [
         (s if i % 2 == 0 or _re_doc_ignore.search(splits[i - 1]) is not None else style_docstring(s, max_len=max_len))
         for i, s in enumerate(splits)
     ]
-    clean_code = '"""'.join(splits)
+    clean_code = '\"\"\"'.join(splits)
+    # fmt: on
 
     diff = clean_code != code
     if not check_only and diff:

utils/tests_fetcher.py

@@ -0,0 +1,427 @@
+# coding=utf-8
+# Copyright 2021 The HuggingFace Inc. team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import argparse
+import collections
+import os
+import re
+from contextlib import contextmanager
+from pathlib import Path
+
+from git import Repo
+
+
+# This script is intended to be run from the root of the repo but you can adapt this constant if you need to.
+PATH_TO_TRANFORMERS = "."
+
+
+@contextmanager
+def checkout_commit(repo, commit_id):
+    """
+    Context manager that checks out a commit in the repo.
+    """
+    current_head = repo.head.commit if repo.head.is_detached else repo.head.ref
+
+    try:
+        repo.git.checkout(commit_id)
+        yield
+
+    finally:
+        repo.git.checkout(current_head)
+
+
+def clean_code(content):
+    """
+    Remove docstrings, empty line or comments from `content`.
+    """
+    # fmt: off
+    # Remove docstrings by splitting on triple " then triple ':
+    splits = content.split('\"\"\"')
+    content = "".join(splits[::2])
+    splits = content.split("\'\'\'")
+    # fmt: on
+    content = "".join(splits[::2])
+
+    # Remove empty lines and comments
+    lines_to_keep = []
+    for line in content.split("\n"):
+        # remove anything that is after a # sign.
+        line = re.sub("#.*$", "", line)
+        if len(line) == 0 or line.isspace():
+            continue
+        lines_to_keep.append(line)
+    return "\n".join(lines_to_keep)
+
+
+def diff_is_docstring_only(repo, branching_point, filename):
+    """
+    Check if the diff is only in docstrings in a filename.
+    """
+    with checkout_commit(repo, branching_point):
+        with open(filename, "r", encoding="utf-8") as f:
+            old_content = f.read()
+
+    with open(filename, "r", encoding="utf-8") as f:
+        new_content = f.read()
+
+    old_content_clean = clean_code(old_content)
+    new_content_clean = clean_code(new_content)
+
+    return old_content_clean == new_content_clean
+
+
+def get_modified_python_files():
+    """
+    Return a list of python files that have been modified between the current head and the master branch.
+    """
+    repo = Repo(PATH_TO_TRANFORMERS)
+
+    print(f"Master is at {repo.refs.master.commit}")
+    print(f"Current head is at {repo.head.commit}")
+
+    branching_commits = repo.merge_base(repo.refs.master, repo.head)
+    for commit in branching_commits:
+        print(f"Branching commit: {commit}")
+
+    print("\n### DIFF ###\n")
+    code_diff = []
+    for commit in branching_commits:
+        for diff_obj in commit.diff(repo.head.commit):
+            # We always add new python files
+            if diff_obj.change_type == "A" and diff_obj.b_path.endswith(".py"):
+                code_diff.append(diff_obj.b_path)
+            # We check that deleted python files won't break corresponding tests.
+            elif diff_obj.change_type == "D" and diff_obj.a_path.endswith(".py"):
+                code_diff.append(diff_obj.a_path)
+            # Now for modified files
+            elif diff_obj.change_type in ["M", "R"] and diff_obj.b_path.endswith(".py"):
+                # In case of renames, we'll look at the tests using both the old and new name.
+                if diff_obj.a_path != diff_obj.b_path:
+                    code_diff.extend([diff_obj.a_path, diff_obj.b_path])
+                else:
+                    # Otherwise, we check modifications are in code and not docstrings.
+                    if diff_is_docstring_only(repo, commit, diff_obj.b_path):
+                        print(f"Ignoring diff in {diff_obj.b_path} as it only concerns docstrings or comments.")
+                    else:
+                        code_diff.append(diff_obj.a_path)
+
+    return code_diff
+
+
+def get_module_dependencies(module_fname):
+    """
+    Get the dependencies of a module.
+    """
+    with open(os.path.join(PATH_TO_TRANFORMERS, module_fname), "r", encoding="utf-8") as f:
+        content = f.read()
+
+    module_parts = module_fname.split(os.path.sep)
+    imported_modules = []
+
+    # Let's start with relative imports
+    relative_imports = re.findall(r"from\s+(\.+\S+)\s+import\s+\S+\s", content)
+    for imp in relative_imports:
+        level = 0
+        while imp.startswith("."):
+            imp = imp[1:]
+            level += 1
+
+        if len(imp) > 0:
+            dep_parts = module_parts[: len(module_parts) - level] + imp.split(".")
+        else:
+            dep_parts = module_parts[: len(module_parts) - level] + ["__init__.py"]
+        imported_module = os.path.sep.join(dep_parts)
+        # We ignore the main init import as it's only for the __version__ that it's done
+        # and it would add everything as a dependency.
+        if not imported_module.endswith("transformers/__init__.py"):
+            imported_modules.append(imported_module)
+
+    # Let's continue with direct imports
+    # The import from the transformers module are ignored for the same reason we ignored the
+    # main init before.
+    direct_imports = re.findall(r"from\s+transformers\.(\S+)\s+import\s+\S+\s", content)
+    for imp in direct_imports:
+        import_parts = imp.split(".")
+        dep_parts = ["src", "transformers"] + import_parts
+        imported_modules.append(os.path.sep.join(dep_parts))
+
+    # Now let's just check that we have proper module files, or append an init for submodules
+    dependencies = []
+    for imported_module in imported_modules:
+        if os.path.isfile(os.path.join(PATH_TO_TRANFORMERS, f"{imported_module}.py")):
+            dependencies.append(f"{imported_module}.py")
+        elif os.path.isdir(os.path.join(PATH_TO_TRANFORMERS, imported_module)) and os.path.isfile(
+            os.path.sep.join([PATH_TO_TRANFORMERS, imported_module, "__init__.py"])
+        ):
+            dependencies.append(os.path.sep.join([imported_module, "__init__.py"]))
+    return dependencies
+
+
+def create_reverse_dependency_map():
+    """
+    Create the dependency map from module filename to the list of modules that depend on it (even recursively).
+    """
+    modules = [
+        str(f.relative_to(PATH_TO_TRANFORMERS))
+        for f in (Path(PATH_TO_TRANFORMERS) / "src/transformers").glob("**/*.py")
+    ]
+    # We grab all the dependencies of each module.
+    direct_deps = {m: get_module_dependencies(m) for m in modules}
+
+    # This recurses the dependencies
+    something_changed = True
+    while something_changed:
+        something_changed = False
+        for m in modules:
+            for d in direct_deps[m]:
+                for dep in direct_deps[d]:
+                    if dep not in direct_deps[m]:
+                        direct_deps[m].append(dep)
+                        something_changed = True
+
+    # Finally we can build the reverse map.
+    reverse_map = collections.defaultdict(list)
+    for m in modules:
+        for d in direct_deps[m]:
+            reverse_map[d].append(m)
+
+    return reverse_map
+
+
+# Any module file that has a test name which can't be inferred automatically from its name should go here. A better
+# approach is to (re-)name the test file accordingly, and second best to add the correspondence map here.
+SPECIAL_MODULE_TO_TEST_MAP = {
+    "configuration_utils.py": "test_configuration_common.py",
+    "convert_graph_to_onnx.py": "test_onnx.py",
+    "data/data_collator.py": "test_data_collator.py",
+    "deepspeed.py": "deepspeed/",
+    "feature_extraction_sequence_utils.py": "test_sequence_feature_extraction_common.py",
+    "feature_extraction_utils.py": "test_feature_extraction_common.py",
+    "file_utils.py": ["test_file_utils.py", "test_model_output.py"],
+    "modelcard.py": "test_model_card.py",
+    "modeling_flax_utils.py": "test_modeling_flax_common.py",
+    "modeling_tf_utils.py": "test_modeling_tf_common.py",
+    "modeling_utils.py": ["test_modeling_common.py", "test_offline.py"],
+    "models/auto/modeling_auto.py": ["test_modeling_auto.py", "test_modeling_tf_pytorch.py", "test_modeling_bort.py"],
+    "models/auto/modeling_flax_auto.py": "test_flax_auto.py",
+    "models/auto/modeling_tf_auto.py": [
+        "test_modeling_tf_auto.py",
+        "test_modeling_tf_pytorch.py",
+        "test_modeling_tf_bort.py",
+    ],
+    "models/blenderbot_small/tokenization_blenderbot_small.py": "test_tokenization_small_blenderbot.py",
+    "models/blenderbot_small/tokenization_blenderbot_small_fast.py": "test_tokenization_small_blenderbot.py",
+    "models/gpt2/modeling_gpt2.py": ["test_modeling_gpt2.py", "test_modeling_megatron_gpt2.py"],
+    "pipelines/base.py": "test_pipelines_common.py",
+    "pipelines/text2text_generation.py": [
+        "test_pipelines_text2text_generation.py",
+        "test_pipelines_summarization.py",
+        "test_pipelines_translation.py",
+    ],
+    "pipelines/zero_shot_classification.py": "test_pipelines_zero_shot.py",
+    "testing_utils.py": "test_skip_decorators.py",
+    "tokenization_utils.py": "test_tokenization_common.py",
+    "tokenization_utils_base.py": "test_tokenization_common.py",
+    "tokenization_utils_fast.py": "test_tokenization_fast.py",
+    "trainer.py": [
+        "test_trainer.py",
+        "extended/test_trainer_ext.py",
+        "test_trainer_distributed.py",
+        "test_trainer_tpu.py",
+    ],
+    "utils/versions.py": "test_versions_utils.py",
+}
+
+
+def module_to_test_file(module_fname):
+    """
+    Returns the name of the file(s) where `module_fname` is tested.
+    """
+    splits = module_fname.split(os.path.sep)
+
+    # Special map has priority
+    short_name = os.path.sep.join(splits[2:])
+    if short_name in SPECIAL_MODULE_TO_TEST_MAP:
+        test_file = SPECIAL_MODULE_TO_TEST_MAP[short_name]
+        if isinstance(test_file, str):
+            return f"tests/{test_file}"
+        return [f"tests/{f}" for f in test_file]
+
+    module_name = splits[-1]
+    # Fast tokenizers are tested in the same file as the slow ones.
+    if module_name.endswith("_fast.py"):
+        module_name = module_name.replace("_fast.py", ".py")
+
+    # Special case for pipelines submodules
+    if len(splits) >= 2 and splits[-2] == "pipelines":
+        default_test_file = f"tests/test_pipelines_{module_name}"
+    # Special case for benchmarks submodules
+    elif len(splits) >= 2 and splits[-2] == "benchmark":
+        return ["tests/test_benchmark.py", "tests/test_benchmark_tf.py"]
+    # Special case for commands submodules
+    elif len(splits) >= 2 and splits[-2] == "commands":
+        return "tests/test_cli.py"
+    # Special case for onnx submodules
+    elif len(splits) >= 2 and splits[-2] == "onnx":
+        return ["tests/test_onnx.py", "tests/test_onnx_v2.py"]
+    # Special case for utils (not the one in src/transformers, the ones at the root of the repo).
+    elif len(splits) > 0 and splits[0] == "utils":
+        default_test_file = f"tests/test_utils_{module_name}"
+    else:
+        default_test_file = f"tests/test_{module_name}"
+
+    if os.path.isfile(default_test_file):
+        return default_test_file
+
+    # Processing -> processor
+    if "processing" in default_test_file:
+        test_file = default_test_file.replace("processing", "processor")
+        if os.path.isfile(test_file):
+            return test_file
+
+
+# This list contains the list of test files we expect never to be launched from a change in a module/util. Those are
+# launched separately.
+EXPECTED_TEST_FILES_NEVER_TOUCHED = [
+    "tests/test_doc_samples.py",  # Doc tests
+    "tests/sagemaker/test_single_node_gpu.py",  # SageMaker test
+    "tests/sagemaker/test_multi_node_model_parallel.py",  # SageMaker test
+    "tests/sagemaker/test_multi_node_data_parallel.py",  # SageMaker test
+]
+
+
+def _print_list(l):
+    return "\n".join([f"- {f}" for f in l])
+
+
+def sanity_check():
+    """
+    Checks that all test files can be touched by a modification in at least one module/utils. This test ensures that
+    newly-added test files are properly mapped to some module or utils, so they can be run by the CI.
+    """
+    # Grab all module and utils
+    all_files = [
+        str(p.relative_to(PATH_TO_TRANFORMERS))
+        for p in (Path(PATH_TO_TRANFORMERS) / "src/transformers").glob("**/*.py")
+    ]
+    all_files += [
+        str(p.relative_to(PATH_TO_TRANFORMERS)) for p in (Path(PATH_TO_TRANFORMERS) / "utils").glob("**/*.py")
+    ]
+
+    # Compute all the test files we get from those.
+    test_files_found = []
+    for f in all_files:
+        test_f = module_to_test_file(f)
+        if test_f is not None:
+            if isinstance(test_f, str):
+                test_files_found.append(test_f)
+            else:
+                test_files_found.extend(test_f)
+
+    # Some of the test files might actually be subfolders so we grab the tests inside.
+    test_files = []
+    for test_f in test_files_found:
+        if os.path.isdir(os.path.join(PATH_TO_TRANFORMERS, test_f)):
+            test_files.extend(
+                [
+                    str(p.relative_to(PATH_TO_TRANFORMERS))
+                    for p in (Path(PATH_TO_TRANFORMERS) / test_f).glob("**/test*.py")
+                ]
+            )
+        else:
+            test_files.append(test_f)
+
+    # Compare to existing test files
+    existing_test_files = [
+        str(p.relative_to(PATH_TO_TRANFORMERS)) for p in (Path(PATH_TO_TRANFORMERS) / "tests").glob("**/test*.py")
+    ]
+    not_touched_test_files = [f for f in existing_test_files if f not in test_files]
+
+    should_be_tested = set(not_touched_test_files) - set(EXPECTED_TEST_FILES_NEVER_TOUCHED)
+    if len(should_be_tested) > 0:
+        raise ValueError(
+            "The following test files are not currently associated with any module or utils files, which means they "
+            f"will never get run by the CI:\n{_print_list(should_be_tested)}\n. Make sure the names of these test "
+            "files match the name of the module or utils they are testing, or adapt the constant "
+            "`SPECIAL_MODULE_TO_TEST_MAP` in `utils/tests_fetcher.py` to add them. If your test file is triggered "
+            "separately and is not supposed to be run by the regular CI, add it to the "
+            "`EXPECTED_TEST_FILES_NEVER_TOUCHED` constant instead."
+        )
+
+
+def infer_tests_to_run(output_file):
+    modified_files = get_modified_python_files()
+    print(f"\n### MODIFIED FILES ###\n{_print_list(modified_files)}")
+
+    # Create the map that will give us all impacted modules.
+    impacted_modules_map = create_reverse_dependency_map()
+    impacted_files = modified_files.copy()
+    for f in modified_files:
+        if f in impacted_modules_map:
+            impacted_files.extend(impacted_modules_map[f])
+
+    # Remove duplicates
+    impacted_files = sorted(list(set(impacted_files)))
+    print(f"\n### IMPACTED FILES ###\n{_print_list(impacted_files)}")
+
+    # Grab the corresponding test files:
+    test_files_to_run = []
+    for f in impacted_files:
+        # Modified test files are always added
+        if f.startswith("tests/"):
+            test_files_to_run.append(f)
+        else:
+            new_tests = module_to_test_file(f)
+            if new_tests is not None:
+                if isinstance(new_tests, str):
+                    test_files_to_run.append(new_tests)
+                else:
+                    test_files_to_run.extend(new_tests)
+
+    # Remove duplicates
+    test_files_to_run = sorted(list(set(test_files_to_run)))
+    print(f"\n### TEST TO RUN ###\n{_print_list(test_files_to_run)}")
+    if len(test_files_to_run) > 0:
+        with open(output_file, "w", encoding="utf-8") as f:
+            f.write(" ".join(test_files_to_run))
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "--sanity_check", action="store_true", help="Only test that all tests and modules are accounted for."
+    )
+    parser.add_argument(
+        "--output_file", type=str, default="test_list.txt", help="Where to store the list of tests to run"
+    )
+    args = parser.parse_args()
+    if args.sanity_check:
+        sanity_check()
+    else:
+        repo = Repo(PATH_TO_TRANFORMERS)
+        # For now we run all tests on the master branch. After testing this more and making sure it works most of the
+        # time, we will apply the same logic to the tests on the master branch and only run the whole suite once per
+        # day.
+        if not repo.head.is_detached and repo.head.ref == repo.refs.master:
+            print("Master branch detected, running all tests.")
+            with open(args.output_file, "w", encoding="utf-8") as f:
+                f.write("./tests/")
+        else:
+            try:
+                infer_tests_to_run(args.output_file)
+            except Exception as e:
+                print(f"\nError when trying to grab the relevant tests: {e}\n\nRunning all tests.")
+                with open(args.output_file, "w", encoding="utf-8") as f:
+                    f.write("./tests/")