Fixing offline mode for pipeline (when inferring task). (#21113)

* Fixing offline mode for pipeline (when inferring task).

* Update src/transformers/pipelines/__init__.py

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* Updating test to reflect change in exception.

* Fixing offline mode.

* Clean.

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

tests/utils/test_offline.py

@@ -15,6 +15,7 @@
 import subprocess
 import sys
 
+from transformers import BertConfig, BertModel, BertTokenizer, pipeline
 from transformers.testing_utils import TestCasePlus, require_torch
 
 
@@ -30,7 +31,7 @@ class OfflineTests(TestCasePlus):
 
         # this must be loaded before socket.socket is monkey-patched
         load = """
-from transformers import BertConfig, BertModel, BertTokenizer
+from transformers import BertConfig, BertModel, BertTokenizer, pipeline
         """
 
         run = """
@@ -38,34 +39,69 @@ mname = "hf-internal-testing/tiny-random-bert"
 BertConfig.from_pretrained(mname)
 BertModel.from_pretrained(mname)
 BertTokenizer.from_pretrained(mname)
+pipe = pipeline(task="fill-mask", model=mname)
 print("success")
         """
 
         mock = """
 import socket
-def offline_socket(*args, **kwargs): raise socket.error("Offline mode is enabled")
+def offline_socket(*args, **kwargs): raise RuntimeError("Offline mode is enabled, we shouldn't access internet")
 socket.socket = offline_socket
         """
 
+        # Force fetching the files so that we can use the cache
+        mname = "hf-internal-testing/tiny-random-bert"
+        BertConfig.from_pretrained(mname)
+        BertModel.from_pretrained(mname)
+        BertTokenizer.from_pretrained(mname)
+        pipeline(task="fill-mask", model=mname)
+
         # baseline - just load from_pretrained with normal network
-        cmd = [sys.executable, "-c", "\n".join([load, run])]
+        cmd = [sys.executable, "-c", "\n".join([load, run, mock])]
 
         # should succeed
         env = self.get_env()
+        # should succeed as TRANSFORMERS_OFFLINE=1 tells it to use local files
+        env["TRANSFORMERS_OFFLINE"] = "1"
         result = subprocess.run(cmd, env=env, check=False, capture_output=True)
         self.assertEqual(result.returncode, 0, result.stderr)
         self.assertIn("success", result.stdout.decode())
 
-        # next emulate no network
-        cmd = [sys.executable, "-c", "\n".join([load, mock, run])]
+    @require_torch
+    def test_offline_mode_no_internet(self):
+        # python one-liner segments
+        # this must be loaded before socket.socket is monkey-patched
+        load = """
+from transformers import BertConfig, BertModel, BertTokenizer, pipeline
+        """
 
-        # Doesn't fail anymore since the model is in the cache due to other tests, so commenting this.
-        # env["TRANSFORMERS_OFFLINE"] = "0"
-        # result = subprocess.run(cmd, env=env, check=False, capture_output=True)
-        # self.assertEqual(result.returncode, 1, result.stderr)
+        run = """
+mname = "hf-internal-testing/tiny-random-bert"
+BertConfig.from_pretrained(mname)
+BertModel.from_pretrained(mname)
+BertTokenizer.from_pretrained(mname)
+pipe = pipeline(task="fill-mask", model=mname)
+print("success")
+        """
 
-        # should succeed as TRANSFORMERS_OFFLINE=1 tells it to use local files
-        env["TRANSFORMERS_OFFLINE"] = "1"
+        mock = """
+import socket
+def offline_socket(*args, **kwargs): raise socket.error("Faking flaky internet")
+socket.socket = offline_socket
+        """
+
+        # Force fetching the files so that we can use the cache
+        mname = "hf-internal-testing/tiny-random-bert"
+        BertConfig.from_pretrained(mname)
+        BertModel.from_pretrained(mname)
+        BertTokenizer.from_pretrained(mname)
+        pipeline(task="fill-mask", model=mname)
+
+        # baseline - just load from_pretrained with normal network
+        cmd = [sys.executable, "-c", "\n".join([load, run, mock])]
+
+        # should succeed
+        env = self.get_env()
         result = subprocess.run(cmd, env=env, check=False, capture_output=True)
         self.assertEqual(result.returncode, 0, result.stderr)
         self.assertIn("success", result.stdout.decode())
@@ -93,7 +129,7 @@ print("success")
 
         mock = """
 import socket
-def offline_socket(*args, **kwargs): raise socket.error("Offline mode is enabled")
+def offline_socket(*args, **kwargs): raise ValueError("Offline mode is enabled")
 socket.socket = offline_socket
         """
 
@@ -119,3 +155,27 @@ socket.socket = offline_socket
         result = subprocess.run(cmd, env=env, check=False, capture_output=True)
         self.assertEqual(result.returncode, 0, result.stderr)
         self.assertIn("success", result.stdout.decode())
+
+    @require_torch
+    def test_offline_mode_pipeline_exception(self):
+        load = """
+from transformers import pipeline
+        """
+        run = """
+mname = "hf-internal-testing/tiny-random-bert"
+pipe = pipeline(model=mname)
+        """
+
+        mock = """
+import socket
+def offline_socket(*args, **kwargs): raise socket.error("Offline mode is enabled")
+socket.socket = offline_socket
+        """
+        env = self.get_env()
+        env["TRANSFORMERS_OFFLINE"] = "1"
+        cmd = [sys.executable, "-c", "\n".join([load, mock, run])]
+        result = subprocess.run(cmd, env=env, check=False, capture_output=True)
+        self.assertEqual(result.returncode, 1, result.stderr)
+        self.assertIn(
+            "You cannot infer task automatically within `pipeline` when using offline mode", result.stderr.decode()
+        )