Fixed setting run_time of :class:.Succession after creating the animation object

manim/animation/composition.py

@@ -166,7 +166,7 @@ def next_animation(self) -> None:
         self.update_active_animation(self.active_index + 1)
 
     def interpolate(self, alpha: float) -> None:
-        current_time = self.rate_func(alpha) * self.run_time
+        current_time = self.rate_func(alpha) * self.max_end_time
         while self.active_end_time is not None and current_time >= self.active_end_time:
             self.next_animation()
         if self.active_animation is not None and self.active_start_time is not None:

tests/module/animation/test_composition.py

@@ -90,6 +90,26 @@ def test_succession_in_succession_timing():
     assert nested_succession.active_animation is None
 
 
+def test_timescaled_succession():
+    s1, s2, s3 = Square(), Square(), Square()
+    anim = Succession(
+        FadeIn(s1, run_time=2),
+        FadeIn(s2),
+        FadeIn(s3),
+    )
+    anim.scene = MagicMock()
+    anim.run_time = 42
+    anim.begin()
+    anim.interpolate(0.2)
+    assert anim.active_index == 0
+    anim.interpolate(0.4)
+    assert anim.active_index == 0
+    anim.interpolate(0.6)
+    assert anim.active_index == 1
+    anim.interpolate(0.8)
+    assert anim.active_index == 2
+
+
 def test_animationbuilder_in_group():
     sqr = Square()
     circ = Circle()