diff --git a/tensorflow_privacy/privacy/membership_inference_attack/data_structures_test.py b/tensorflow_privacy/privacy/membership_inference_attack/data_structures_test.py
index d5c9d1d..80f4ca4 100644
--- a/tensorflow_privacy/privacy/membership_inference_attack/data_structures_test.py
+++ b/tensorflow_privacy/privacy/membership_inference_attack/data_structures_test.py
@@ -22,6 +22,7 @@ import numpy as np
 import pandas as pd
 from tensorflow_privacy.privacy.membership_inference_attack.data_structures import _log_value
 from tensorflow_privacy.privacy.membership_inference_attack.data_structures import AttackInputData
+from tensorflow_privacy.privacy.membership_inference_attack.data_structures import Seq2SeqAttackInputData
 from tensorflow_privacy.privacy.membership_inference_attack.data_structures import AttackResults
 from tensorflow_privacy.privacy.membership_inference_attack.data_structures import AttackResultsCollection
 from tensorflow_privacy.privacy.membership_inference_attack.data_structures import AttackType
@@ -142,6 +143,70 @@ class AttackInputDataTest(absltest.TestCase):
             probs_test=np.array([])).validate)
 
 
+class Seq2SeqAttackInputDataTest(absltest.TestCase):
+  def test_validator(self):
+    valid_logits_train = iter([np.array([]), np.array([])])
+    valid_logits_test = iter([np.array([]), np.array([])])
+    valid_labels_train = iter([np.array([]), np.array([])])
+    valid_labels_test = iter([np.array([]), np.array([])])
+
+    invalid_logits_train = []
+    invalid_logits_test = []
+    invalid_labels_train = []
+    invalid_labels_test = []
+
+    self.assertRaises(ValueError,
+                      Seq2SeqAttackInputData(logits_train=valid_logits_train).validate)
+    self.assertRaises(ValueError,
+                      Seq2SeqAttackInputData(labels_train=valid_labels_train).validate)
+    self.assertRaises(ValueError,
+                      Seq2SeqAttackInputData(logits_test=valid_logits_test).validate)
+    self.assertRaises(ValueError,
+                      Seq2SeqAttackInputData(labels_test=valid_labels_test).validate)
+    self.assertRaises(ValueError,
+                      Seq2SeqAttackInputData(vocab_size=0).validate)
+    self.assertRaises(ValueError,
+                      Seq2SeqAttackInputData(train_size=0).validate)
+    self.assertRaises(ValueError,
+                      Seq2SeqAttackInputData(test_size=0).validate)
+    self.assertRaises(ValueError, Seq2SeqAttackInputData().validate)
+
+    # Tests that both logits and labels must be set.
+    self.assertRaises(ValueError,
+                      Seq2SeqAttackInputData(
+                        logits_train=valid_logits_train,
+                        logits_test=valid_logits_test,
+                        vocab_size=0,
+                        train_size=0,
+                        test_size=0).validate)
+    self.assertRaises(ValueError,
+                      Seq2SeqAttackInputData(
+                        labels_train=valid_labels_train,
+                        labels_test=valid_labels_test,
+                        vocab_size=0,
+                        train_size=0,
+                        test_size=0).validate)
+
+    # Tests that vocab, train, test sizes must all be set.
+    self.assertRaises(ValueError,
+                      Seq2SeqAttackInputData(
+                        logits_train=valid_logits_train,
+                        logits_test=valid_logits_test,
+                        labels_train=valid_labels_train,
+                        labels_test=valid_labels_test).validate)
+
+    self.assertRaises(ValueError,
+                      Seq2SeqAttackInputData(
+                        logits_train=invalid_logits_train,
+                        logits_test=invalid_logits_test,
+                        labels_train=invalid_labels_train,
+                        labels_test=invalid_labels_test,
+                        vocab_size=0,
+                        train_size=0,
+                        test_size=0
+                      ).validate)
+
+
 class RocCurveTest(absltest.TestCase):
 
   def test_auc_random_classifier(self):
@@ -265,7 +330,6 @@ class AttackResultsCollectionTest(absltest.TestCase):
 
 
 class AttackResultsTest(absltest.TestCase):
-
   perfect_classifier_result: SingleAttackResult
   random_classifier_result: SingleAttackResult