can't pass list of colors in set_color() fixed (#993)

* can't pass list of colors in set_color() fixed

* Add gradient test

* black

* black

Author: sparshg

manim/mobject/types/vectorized_mobject.py

@@ -280,7 +280,12 @@ def match_style(self, vmobject, family=True):
     def set_color(self, color, family=True):
         self.set_fill(color, family=family)
         self.set_stroke(color, family=family)
-        self.color = colour.Color(color)
+
+        # check if a list of colors is passed to color
+        if isinstance(color, str):
+            self.color = colour.Color(color)
+        else:
+            self.color = color
         return self
 
     def set_opacity(self, opacity, family=True):

tests/control_data/graphical_units_data/modifier_methods/GradientTest.npz

@@ -0,0 +1,19 @@
+import pytest
+
+from manim import *
+from ..utils.testing_utils import get_scenes_to_test
+from ..utils.GraphicalUnitTester import GraphicalUnitTester
+
+
+class GradientTest(Scene):
+    def construct(self):
+        c = Circle(fill_opacity=1).set_color(color=[YELLOW, GREEN])
+        self.play(Animation(c))
+
+
+MODULE_NAME = "modifier_methods"
+
+
+@pytest.mark.parametrize("scene_to_test", get_scenes_to_test(__name__), indirect=False)
+def test_scene(scene_to_test, tmpdir, show_diff):
+    GraphicalUnitTester(scene_to_test[1], MODULE_NAME, tmpdir).test(show_diff=show_diff)