Add new token classification example (#8340)

* Add new token classification example

* Remove txt file

* Add test

* With actual testing done

* Less warmup is better

* Update examples/token-classification/run_ner_new.py

Co-authored-by: Thomas Wolf <thomwolf@users.noreply.github.com>

* Address review comments

* Fix test

* Make Lysandre happy

* Last touches and rename

* Rename in tests

* Address review comments

* More run_ner -> run_ner_old

Co-authored-by: Thomas Wolf <thomwolf@users.noreply.github.com>

examples/test_examples.py

@@ -28,7 +28,13 @@ from transformers.testing_utils import TestCasePlus, torch_device
 
 SRC_DIRS = [
     os.path.join(os.path.dirname(__file__), dirname)
-    for dirname in ["text-generation", "text-classification", "language-modeling", "question-answering"]
+    for dirname in [
+        "text-generation",
+        "text-classification",
+        "token-classification",
+        "language-modeling",
+        "question-answering",
+    ]
 ]
 sys.path.extend(SRC_DIRS)
 
@@ -38,6 +44,7 @@ if SRC_DIRS is not None:
     import run_generation
     import run_glue
     import run_mlm
+    import run_ner
     import run_pl_glue
     import run_squad
 
@@ -185,6 +192,36 @@ class ExamplesTests(TestCasePlus):
             result = run_mlm.main()
             self.assertLess(result["perplexity"], 42)
 
+    def test_run_ner(self):
+        stream_handler = logging.StreamHandler(sys.stdout)
+        logger.addHandler(stream_handler)
+
+        tmp_dir = self.get_auto_remove_tmp_dir()
+        testargs = f"""
+            run_ner.py
+            --model_name_or_path bert-base-uncased
+            --train_file tests/fixtures/tests_samples/conll/sample.json
+            --validation_file tests/fixtures/tests_samples/conll/sample.json
+            --output_dir {tmp_dir}
+            --overwrite_output_dir
+            --do_train
+            --do_eval
+            --warmup_steps=2
+            --learning_rate=2e-4
+            --per_gpu_train_batch_size=2
+            --per_gpu_eval_batch_size=2
+            --num_train_epochs=2
+        """.split()
+
+        if torch_device != "cuda":
+            testargs.append("--no_cuda")
+
+        with patch.object(sys, "argv", testargs):
+            result = run_ner.main()
+            self.assertGreaterEqual(result["eval_accuracy_score"], 0.75)
+            self.assertGreaterEqual(result["eval_precision"], 0.75)
+            self.assertLess(result["eval_loss"], 0.5)
+
     def test_run_squad(self):
         stream_handler = logging.StreamHandler(sys.stdout)
         logger.addHandler(stream_handler)