diff --git a/obstools/tests/test_deveny_grangle.py b/obstools/tests/test_deveny_grangle.py
index 37f9239..60f9d42 100644
--- a/obstools/tests/test_deveny_grangle.py
+++ b/obstools/tests/test_deveny_grangle.py
@@ -1,3 +1,4 @@
+# pylint: disable=missing-function-docstring
 # -*- coding: utf-8 -*-
 #
 #  This file is part of LDTObserverTools.
@@ -13,27 +14,51 @@
 """DeVeny Grating Angle Calculator TEST Module
 """
 
-import pytest
+import numpy as np
 
-def test_deveny_grangle_cli():
-    assert 1 == 1
+from obstools import deveny_grangle
 
-
-def test_deveny_grangle_gui():
-    assert 1 == 1
+# NOTE: No unit tests for deveny_grangle_cli() and deveny_grangle_gui()
+#       functions.  Need to find another way to test those.
 
 
 def test_compute_grangle():
-    assert 1 == 1
+    grangle, amag = deveny_grangle.compute_grangle(400, 8000)
+    # Ensure returns are floats and the correct values
+    assert isinstance(grangle, float)
+    assert isinstance(amag, float)
+    assert np.isclose(grangle, 27.8919, atol=1.0e-4)
+    assert np.isclose(amag, 0.8257, atol=1.0e-4)
 
 
 def test_grangle_eqn():
-    assert 1 == 1
+    zero = deveny_grangle.grangle_eqn(np.deg2rad(22.54), 300, 5195)
+    # Ensure zero is a float and of the correct value
+    assert isinstance(zero, float)
+    assert np.isclose(zero, 0, atol=1)
+    # Check another grating
+    zero = deveny_grangle.grangle_eqn(np.deg2rad(21.00), 150, 7220)
+    assert np.isclose(zero, 0, atol=1)
 
 
 def test_lambda_at_angle():
-    assert 1 == 1
+    cenwave = deveny_grangle.lambda_at_angle(22.54, 300)
+    # Ensure cenwave is a float and of the correct value
+    assert isinstance(cenwave, float)
+    assert np.isclose(cenwave, 5195, atol=1)
+    # Check another grating
+    cenwave = deveny_grangle.lambda_at_angle(25.60, 500)
+    assert np.isclose(cenwave, 5000, atol=1)
+    # Test the radians option
+    cenwave = deveny_grangle.lambda_at_angle(np.deg2rad(40.96), 831, radians=True)
+    assert np.isclose(cenwave, 8499, atol=1)
 
 
 def test_deveny_amag():
-    assert 1 == 1
+    amag = deveny_grangle.deveny_amag(22.54)
+    # Ensure amag is a float of the correct value
+    assert isinstance(amag, float)
+    assert np.isclose(amag, 0.9122, atol=1.0e-4)
+    # Check another value
+    amag = deveny_grangle.deveny_amag(27.04)
+    assert np.isclose(amag, 0.8391, atol=1.0e-4)