diff --git a/tests/test_common.py b/tests/test_common.py
new file mode 100644
index 0000000..c162990
--- /dev/null
+++ b/tests/test_common.py
@@ -0,0 +1,69 @@
+import numpy as np
+from PIL import Image, ImageDraw
+
+from adetailer.common import create_bbox_from_mask, create_mask_from_bbox
+
+
+def test_create_mask_from_bbox():
+    img = Image.new("L", (10, 10), color="black")
+    bbox = [[1.0, 1.0, 2.0, 2.0], [7.0, 7.0, 8.0, 8.0]]
+    masks = create_mask_from_bbox(bbox, img.size)
+    expect1 = np.array(
+        [
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 255, 255, 0, 0, 0, 0, 0, 0, 0],
+            [0, 255, 255, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+        ],
+        dtype=np.uint8,
+    )
+    expect2 = np.array(
+        [
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 255, 255, 0],
+            [0, 0, 0, 0, 0, 0, 0, 255, 255, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+        ],
+        dtype=np.uint8,
+    )
+    assert len(masks) == len(bbox)
+    arr1 = np.array(masks[0])
+    arr2 = np.array(masks[1])
+    assert arr1.shape == expect1.shape
+    assert arr2.shape == expect2.shape
+    assert arr1.shape == (10, 10)
+    assert arr1.dtype == expect1.dtype
+    assert arr2.dtype == expect2.dtype
+    assert np.array_equal(arr1, expect1)
+    assert np.array_equal(arr2, expect2)
+
+    # The function correctly receives a list of masks and the shape of the image.
+
+
+def test_create_bbox_from_mask():
+    mask = Image.new("L", (10, 10), color="black")
+    draw = ImageDraw.Draw(mask)
+    draw.rectangle((2, 2, 5, 5), fill="white")
+
+    result = create_bbox_from_mask([mask], (10, 10))
+
+    assert isinstance(result, list)
+    assert len(result) == 1
+    assert all(isinstance(bbox, list) for bbox in result)
+    assert all(len(bbox) == 4 for bbox in result)
+    assert result[0] == [2, 2, 6, 6]
+
+    result = create_bbox_from_mask([mask], (256, 256))
+    assert result[0] == [38, 38, 166, 166]