[s2s] add create student script (#7290)

Co-authored-by: Suraj Patil <surajp815@gmail.com>
Co-authored-by: Sam Shleifer <sshleifer@gmail.com>

examples/seq2seq/test_make_student.py

@@ -0,0 +1,41 @@
+import tempfile
+import unittest
+
+from make_student import create_student_by_copying_alternating_layers
+from transformers import AutoConfig
+from transformers.file_utils import cached_property
+from transformers.testing_utils import require_torch
+
+
+TINY_BART = "sshleifer/bart-tiny-random"
+TINY_T5 = "patrickvonplaten/t5-tiny-random"
+
+
+@require_torch
+class MakeStudentTester(unittest.TestCase):
+    @cached_property
+    def teacher_config(self):
+        return AutoConfig.from_pretrained(TINY_BART)
+
+    def test_valid_t5(self):
+        student, *_ = create_student_by_copying_alternating_layers(TINY_T5, tempfile.mkdtemp(), e=1, d=1)
+        self.assertEqual(student.config.num_hidden_layers, 1)
+
+    def test_invalid_t5(self):
+        # T5 students must have the same e==d because there is only one config property
+        with self.assertRaises(AssertionError):
+            student, *_ = create_student_by_copying_alternating_layers(TINY_T5, tempfile.mkdtemp(), e=1, d=None)
+
+    def test_same_decoder_small_encoder(self):
+        student, *_ = create_student_by_copying_alternating_layers(TINY_BART, tempfile.mkdtemp(), e=1, d=None)
+        self.assertEqual(student.config.encoder_layers, 1)
+        self.assertEqual(student.config.decoder_layers, self.teacher_config.encoder_layers)
+
+    def test_small_enc_small_dec(self):
+        student, *_ = create_student_by_copying_alternating_layers(TINY_BART, tempfile.mkdtemp(), e=1, d=1)
+        self.assertEqual(student.config.encoder_layers, 1)
+        self.assertEqual(student.config.decoder_layers, 1)
+
+    def test_raises_assert(self):
+        with self.assertRaises(AssertionError):
+            create_student_by_copying_alternating_layers(TINY_BART, tempfile.mkdtemp(), e=None, d=None)