--- a
+++ b/test/features/test_pos_feature.py
@@ -0,0 +1,80 @@
+# Base Dependencies
+# ----------------
+import pytest
+import numpy as np
+
+# Local Dependencies
+# ------------------
+from features.pos_feature import POSFeature
+from constants import U_POS_TAGS
+from models import RelationCollection, Entity
+from models.relation import Relation, RelationN2C2
+
+
+# Tests
+# ------
+def test_pos_init():
+    pos = POSFeature()
+    assert isinstance(pos, POSFeature)
+    assert pos.padding_idx is None
+
+
+def test_pos_get_feature_names():
+    pos = POSFeature()
+    assert pos.get_feature_names() == ["POS"]
+
+
+def test_pos_fit(n2c2_small_collection):
+    pos = POSFeature()
+    pos = pos.fit(n2c2_small_collection)
+    assert isinstance(pos, POSFeature)
+
+
+def test_pos_index():
+    for padding_idx in [0, 1, 5]:
+        pos = POSFeature(padding_idx=padding_idx)
+
+        for tag in U_POS_TAGS:
+            idx = pos.pos_index(tag)
+            assert idx != padding_idx
+
+
+def test_pos_index_unknown_tag_raises():
+    pos = POSFeature()
+    with pytest.raises(Exception):
+        idx = pos.pos_index("B-UNKN")
+
+
+def test_pos_create_pos_feature_dimensions(n2c2_small_collection, NLP):
+    RelationCollection.set_nlp(NLP)
+
+    pos = POSFeature()
+    pos_feature = pos.create_pos_feature(n2c2_small_collection)
+    assert len(pos_feature) == len(n2c2_small_collection)
+
+    for i in range(len(n2c2_small_collection)):
+        assert len(pos_feature[i]) == len(n2c2_small_collection.tokens[i])
+
+
+def test_pos_create_pos_feature_values(relation, NLP):
+    RelationCollection.set_nlp(NLP)
+
+    one_collection = RelationCollection(relation)
+
+    pos = POSFeature()
+    pos_feature = pos.create_pos_feature(one_collection)
+    pos_tags = [
+        "PRON",
+        "AUX",
+        "VERB",
+        "PROPN",
+        "CCONJ",
+        "PROPN",
+        "NUM",
+        "NOUN",
+        "ADP",
+        "NUM",
+        "NOUN",
+    ]
+    pos_idx = [pos.pos_index(t) for t in pos_tags]
+    assert pos_feature[0] == pos_idx