Raise type error for the unsupported object type

paz/processors/draw.py

@@ -26,10 +26,19 @@ def __init__(self, class_names=None, colors=None,
         self.colors = colors
         self.weighted = weighted
         self.scale = scale
+
+        if (self.class_names is not None and
+                not isinstance(self.class_names, list)):
+            raise TypeError("Class name should be of type 'List of strings'")
+
+        if (self.colors is not None and
+                not all(isinstance(color, list) for color in self.colors)):
+            raise TypeError("Colors should be of type 'List of lists'")
+
         if self.colors is None:
             self.colors = lincolor(len(self.class_names))
 
-        if class_names is not None:
+        if self.class_names is not None:
             self.class_to_color = dict(zip(self.class_names, self.colors))
         else:
             self.class_to_color = {None: self.colors, '': self.colors}

tests/paz/processors/draw_test.py

@@ -0,0 +1,16 @@
+import pytest
+from paz import processors as pr
+
+
+def test_DrawBoxes2D_with_invalid_class_names_type():
+    with pytest.raises(TypeError):
+        class_names = 'Face'
+        colors = [[255, 0, 0]]
+        pr.DrawBoxes2D(class_names, colors)
+
+
+def test_DrawBoxes2D_with_invalid_colors_type():
+    with pytest.raises(TypeError):
+        class_names = ['Face']
+        colors = [255, 0, 0]
+        pr.DrawBoxes2D(class_names, colors)