diff --git a/src/tests/test_conversion/tests_db/test_from_lin.py b/src/tests/test_conversion/tests_db/test_from_lin.py
new file mode 100644
index 0000000000000000000000000000000000000000..d0ae110e068dc93d7ed5cfcbfce0598bb21cde19
--- /dev/null
+++ b/src/tests/test_conversion/tests_db/test_from_lin.py
@@ -0,0 +1,34 @@
+import unittest
+
+import numpy as np
+import pandas as pd
+
+from openqlab.conversion.db import from_lin
+
+
+class TestFromLin(unittest.TestCase):
+    def test_positive_integer(self):
+        self.assertEqual(from_lin(10), 10)
+        self.assertEqual(from_lin(100000), 50)
+        self.assertAlmostEqual(from_lin(1.9952623), 3)
+
+    def test_negative_integer(self):
+        self.assertEqual(from_lin(0.1), -10)
+        self.assertEqual(from_lin(1e-5), -50)
+        self.assertAlmostEqual(from_lin(0.5011872336272722), -3)
+
+    def test_positive_float(self):
+        self.assertAlmostEqual(from_lin(2.23872113), 3.5)
+
+    def test_negative_float(self):
+        self.assertAlmostEqual(from_lin(0.446683592), -3.5)
+
+    def test_dataframe(self):
+        df = pd.DataFrame([10, 0.1, 1e5])
+        expected_df = pd.DataFrame([10, -10, 50], dtype="float64")
+        pd.testing.assert_frame_equal(from_lin(df), expected_df)
+
+    def test_numpy_array(self):
+        a = np.array([10, 0.1, 1e5])
+        expected_array = np.array([10, -10, 50])
+        np.testing.assert_array_equal(from_lin(a), expected_array)
diff --git a/src/tests/test_conversion/tests_db/test_to_lin.py b/src/tests/test_conversion/tests_db/test_to_lin.py
index 37d83efea627432c47533468422aed5f5a6c2f88..2ec1a2ffbddc614e0b9bfd950889b2eb55bde05c 100644
--- a/src/tests/test_conversion/tests_db/test_to_lin.py
+++ b/src/tests/test_conversion/tests_db/test_to_lin.py
@@ -15,7 +15,7 @@ class TestToLin(unittest.TestCase):
     def test_negative_integer(self):
         self.assertEqual(to_lin(-10), 0.1)
         self.assertEqual(to_lin(-50), 1e-5)
-        self.assertAlmostEqual(to_lin(-3), 0.5011872)
+        self.assertAlmostEqual(to_lin(-3), 0.5011872336272722)
 
     def test_positive_float(self):
         self.assertAlmostEqual(to_lin(3.5), 2.23872113)