Add unittest for falsely given font file.

tests/test_tagplot_image.py

@@ -16,7 +16,6 @@ FIG1 = plt.figure()
 IMG1 = "image1.png"
 FIG2 = plt.figure()
 IMG2 = "image2.jpg"
-IMGS_AS_LIST = [IMG1, IMG2]
 
 # Constants for tests
 PROJECT_ID = "MR01"
@@ -40,7 +39,7 @@ class TestTagplotImage(unittest.TestCase):
         respectively.
         """
         options = PlotOptions(
-            IMGS_AS_LIST,
+            [IMG1, IMG2],
             ROTATION,
             POSITION,
             figure_ids=["test123456", "654321tset"],
@@ -89,6 +88,24 @@ class TestTagplotImage(unittest.TestCase):
         with self.assertRaises(TypeError):
             tagplot_image("wrong_object")
 
+    def test_wrong_font(self) -> None:
+        """Test if Warning is raised if a given font file can not be found."""
+        options = PlotOptions(
+            [IMG1, IMG2],
+            ROTATION,
+            POSITION,
+            figure_ids=["test123456", "654321tset"],
+            prefix=PROJECT_ID,
+            id_method=METHOD,
+            qrcode=True,
+            fontsize=10,
+            font="not_existing_font.ttf",
+            fontcolor=(0, 1, 0),
+        )
+        options.validate_input()
+        with self.assertWarns(Warning):
+            tagplot_image(options)
+
     def tearDown(self) -> None:
         os.remove(IMG1)
         os.remove(IMG2)