Added test for the way BytePairTokenizer handles the \n\n sequence, w…

…hich is important in Lama chat templates (keras-team#1912)

* added test for the way BytePairTokenizer handles the \n\n sequence, which is important in Lama chat templates

* un commented the test lines that were commented by mistake

* fixed linter errors

keras_hub/src/tokenizers/byte_pair_tokenizer_test.py

@@ -1,5 +1,4 @@
 import keras
-import pytest
 import tensorflow as tf
 
 from keras_hub.src.tests.test_case import TestCase
@@ -15,7 +14,6 @@
 )
 
 
-@pytest.mark.large
 class BytePairTokenizerTest(TestCase):
     def setUp(self):
         super().setUp()
@@ -111,6 +109,24 @@ def test_whitespace_split(self):
         encoded = self.tokenizer(input_data)
         self.assertAllEqual(encoded, [1437, 1437, 50140, 50118, 29])
 
+        # This is important for Llama3 which uses the \n\n sequence in chat
+        # templates: \n\n must be tokenized as a single token
+        input_data = "Hello\n\nHello"
+        encoded = self.tokenizer(input_data)
+        self.assertAllEqual(encoded, [31414, 50140, 31414])
+
+        input_data = "Hello\n\n\n\nHello"
+        encoded = self.tokenizer(input_data)
+        self.assertAllEqual(encoded, [31414, 50140, 50140, 31414])
+
+        input_data = "Hello\n\n"
+        encoded = self.tokenizer(input_data)
+        self.assertAllEqual(encoded, [31414, 50140])
+
+        input_data = "Hello\n\n\n\n"
+        encoded = self.tokenizer(input_data)
+        self.assertAllEqual(encoded, [31414, 50140, 50140])
+
     def test_special_whitespace(self):
         input_data = "\xa0 \xa0 \x3000 s"
         encoded = self.tokenizer(input_data)