Test invariance of confusion_matrix arguments

nnfwtbn/tests/test_plot.py

@@ -132,6 +132,30 @@ class SurvivalTestCase(unittest.TestCase):
                          annot=True)
         self.assertIsNotNone(data)
 
+    def test_confusion_matrix_argument_reverse(self):
+        """
+        Check that confusion_matrix does not change the arguments.
+        """
+        df = pd.DataFrame({
+                "sick": [0, 1, 1, 0, 0],
+                "positive": [0, 0, 1, 1, 0],
+                "weight": [1, 1, 1, 1.7, 1],
+            })
+
+        positive = Cut(lambda d: d.positive == 1, label="+")
+        negative = Cut(lambda d: d.positive == 0, label="-")
+        sick = Cut(lambda d: d.sick == 1, label="sick")
+        healthy = Cut(lambda d: d.sick == 0, label="healthy")
+
+        x = [positive, negative]
+        y = [sick, healthy]
+
+        confusion_matrix(df, x, y, "Test result", "Truth",
+                         weight=Variable("weight", "weight"))
+
+        self.assertEqual(x, [positive, negative])
+        self.assertEqual(y, [sick, healthy])
+
     def test_atlasify(self):
         """
         Check that calling atlasify() does not raise an error.