[fsmt test] basic config test with online model + super tiny model (#7860)

* basic config test with online model

* typo

* style

* better test

scripts/fsmt/fsmt-make-super-tiny-model.py

+#!/usr/bin/env python
+# coding: utf-8
+
+# This script creates a super tiny model that is useful inside tests, when we just want to test that
+# the machinery works, without needing to the check the quality of the outcomes.
+#
+# This version creates a tiny vocab first, and then a tiny model - so the outcome is truly tiny -
+# all files ~60KB. As compared to taking a full-size model, reducing to the minimum its layers and
+# emb dimensions, but keeping the full vocab + merges files, leading to ~3MB in total for all files.
+# The latter is done by `fsmt-make-super-tiny-model.py`.
+#
+# It will be used then as "stas/tiny-wmt19-en-ru"
+
+from pathlib import Path
+import json
+import tempfile
+
+from transformers import FSMTTokenizer, FSMTConfig, FSMTForConditionalGeneration
+from transformers.tokenization_fsmt import VOCAB_FILES_NAMES
+
+mname_tiny = "tiny-wmt19-en-ru"
+
+# Build
+
+# borrowed from a test 
+vocab = [ "l", "o", "w", "e", "r", "s", "t", "i", "d", "n", "w</w>", "r</w>", "t</w>", "lo", "low", "er</w>", "low</w>", "lowest</w>", "newer</w>", "wider</w>", "<unk>", ]
+vocab_tokens = dict(zip(vocab, range(len(vocab))))
+merges = ["l o 123", "lo w 1456", "e r</w> 1789", ""]
+
+with tempfile.TemporaryDirectory() as tmpdirname:
+    build_dir = Path(tmpdirname)
+    src_vocab_file = build_dir / VOCAB_FILES_NAMES["src_vocab_file"]
+    tgt_vocab_file = build_dir / VOCAB_FILES_NAMES["tgt_vocab_file"]
+    merges_file = build_dir / VOCAB_FILES_NAMES["merges_file"]
+    with open(src_vocab_file, "w") as fp: fp.write(json.dumps(vocab_tokens))
+    with open(tgt_vocab_file, "w") as fp: fp.write(json.dumps(vocab_tokens))
+    with open(merges_file, "w") as fp   : fp.write("\n".join(merges))
+
+    tokenizer = FSMTTokenizer(
+        langs=["en", "ru"],
+        src_vocab_size = len(vocab),
+        tgt_vocab_size = len(vocab),
+        src_vocab_file=src_vocab_file,
+        tgt_vocab_file=tgt_vocab_file,
+        merges_file=merges_file,
+    )
+    
+config = FSMTConfig(
+    langs=['ru', 'en'],
+    src_vocab_size=1000, tgt_vocab_size=1000,
+    d_model=4,
+    encoder_layers=1, decoder_layers=1,
+    encoder_ffn_dim=4, decoder_ffn_dim=4,
+    encoder_attention_heads=1, decoder_attention_heads=1,
+)
+
+tiny_model = FSMTForConditionalGeneration(config)
+print(f"num of params {tiny_model.num_parameters()}")
+
+# Test
+batch = tokenizer.prepare_seq2seq_batch(["Making tiny model"])
+outputs = tiny_model(**batch, return_dict=True)
+
+print("test output:", len(outputs.logits[0]))
+
+# Save
+tiny_model.half() # makes it smaller
+tiny_model.save_pretrained(mname_tiny)
+tokenizer.save_pretrained(mname_tiny)
+
+print(f"Generated {mname_tiny}")
+
+# Upload
+# transformers-cli upload tiny-wmt19-en-ru

scripts/fsmt/fsmt-make-tiny-model.py

 #!/usr/bin/env python
 # coding: utf-8
 
-# this script creates a tiny model that is useful inside tests, when we just want to test that the machinery works,
-# without needing to the check the quality of the outcomes.
-# it will be used then as "stas/tiny-wmt19-en-de"
+# This script creates a super tiny model that is useful inside tests, when we just want to test that
+# the machinery works, without needing to the check the quality of the outcomes.
+#
+# This version creates a tiny model through reduction of a normal pre-trained model, but keeping the
+# full vocab, merges file, and thus also resulting in a larger model due to a large vocab size.
+# This gives ~3MB in total for all files.
+#
+# If you want a 50 times smaller than this see `fsmt-make-super-tiny-model.py`, which is slightly more complicated
+#
+#
+# It will be used then as "stas/tiny-wmt19-en-de"
 
+# Build
 from transformers import FSMTTokenizer, FSMTConfig, FSMTForConditionalGeneration
 mname = "facebook/wmt19-en-de"
 tokenizer = FSMTTokenizer.from_pretrained(mname)
@@ -18,16 +27,20 @@ config.update(dict(
 
 tiny_model = FSMTForConditionalGeneration(config)
 print(f"num of params {tiny_model.num_parameters()}")
-# Test it
+
+# Test
 batch = tokenizer.prepare_seq2seq_batch(["Making tiny model"])
 outputs = tiny_model(**batch, return_dict=True)
 
-print(len(outputs.logits[0]))
+print("test output:", len(outputs.logits[0]))
+
 # Save
 mname_tiny = "tiny-wmt19-en-de"
 tiny_model.half() # makes it smaller
 tiny_model.save_pretrained(mname_tiny)
 tokenizer.save_pretrained(mname_tiny)
 
+print(f"Generated {mname_tiny}")
+
 # Upload
 # transformers-cli upload tiny-wmt19-en-de

tests/test_tokenization_fsmt.py

@@ -25,6 +25,10 @@ from transformers.tokenization_fsmt import VOCAB_FILES_NAMES, FSMTTokenizer
 from .test_tokenization_common import TokenizerTesterMixin
 
 
+# using a different tiny model than the one used for default params defined in init to ensure proper testing
+FSMT_TINY2 = "stas/tiny-wmt19-en-ru"
+
+
 class FSMTTokenizationTest(TokenizerTesterMixin, unittest.TestCase):
     tokenizer_class = FSMTTokenizer
 
@@ -86,6 +90,15 @@ class FSMTTokenizationTest(TokenizerTesterMixin, unittest.TestCase):
     def tokenizer_en_ru(self):
         return FSMTTokenizer.from_pretrained("facebook/wmt19-en-ru")
 
+    def test_online_tokenizer_config(self):
+        """this just tests that the online tokenizer files get correctly fetched and
+        loaded via its tokenizer_config.json and it's not slow so it's run by normal CI
+        """
+        tokenizer = FSMTTokenizer.from_pretrained(FSMT_TINY2)
+        self.assertListEqual([tokenizer.src_lang, tokenizer.tgt_lang], ["en", "ru"])
+        self.assertEqual(tokenizer.src_vocab_size, 21)
+        self.assertEqual(tokenizer.tgt_vocab_size, 21)
+
     def test_full_tokenizer(self):
         """ Adapted from Sennrich et al. 2015 and https://github.com/rsennrich/subword-nmt """
         tokenizer = FSMTTokenizer(self.langs, self.src_vocab_file, self.tgt_vocab_file, self.merges_file)