Improving Pipelines by defaulting to framework='tf' when pytorch seems unavailable. (#7728)

* Improving Pipelines by defaulting to framework='tf' when

pytorch seems unavailable.

* Actually changing the default resolution order to account for model
defaults

Adding a new tests for each pipeline to check that pipeline(task) works
too without manually adding the framework too.

tests/test_pipelines.py

@@ -10,6 +10,7 @@ DEFAULT_DEVICE_NUM = -1 if torch_device == "cpu" else 0
 VALID_INPUTS = ["A simple string", ["list of strings"]]
 
 NER_FINETUNED_MODELS = ["sshleifer/tiny-dbmdz-bert-large-cased-finetuned-conll03-english"]
+TF_NER_FINETUNED_MODELS = ["Narsil/small"]
 
 # xlnet-base-cased disabled for now, since it crashes TF2
 FEATURE_EXTRACT_FINETUNED_MODELS = ["sshleifer/tiny-distilbert-base-cased"]
@@ -804,6 +805,14 @@ class NerPipelineTests(unittest.TestCase):
             nlp = pipeline(task="ner", model=model_name, tokenizer=model_name, framework="tf", grouped_entities=True)
             self._test_ner_pipeline(nlp, mandatory_keys)
 
+    @require_tf
+    def test_tf_only_ner(self):
+        mandatory_keys = {"entity", "word", "score"}
+        for model_name in TF_NER_FINETUNED_MODELS:
+            # We don't specificy framework='tf' but it gets detected automatically
+            nlp = pipeline(task="ner", model=model_name, tokenizer=model_name)
+            self._test_ner_pipeline(nlp, mandatory_keys)
+
 
 class PipelineCommonTests(unittest.TestCase):
     pipelines = SUPPORTED_TASKS.keys()
@@ -815,6 +824,7 @@ class PipelineCommonTests(unittest.TestCase):
         for task in self.pipelines:
             with self.subTest(msg="Testing TF defaults with TF and {}".format(task)):
                 pipeline(task, framework="tf")
+                pipeline(task)
 
     @require_torch
     @slow
@@ -823,3 +833,4 @@ class PipelineCommonTests(unittest.TestCase):
         for task in self.pipelines:
             with self.subTest(msg="Testing Torch defaults with PyTorch and {}".format(task)):
                 pipeline(task, framework="pt")
+                pipeline(task)