From d92157719af4169e342f083ce148a3648735d34e Mon Sep 17 00:00:00 2001
From: Michael Nesen <michael.nesen@shopify.com>
Date: Wed, 8 Jan 2025 16:34:18 +0000
Subject: [PATCH] Fix stacked area arity bug regression

---
 packages/polaris-viz/CHANGELOG.md             |  4 ++
 .../components/StackedAreas/StackedAreas.tsx  |  5 ---
 .../StackedAreas/tests/StackedAreas.test.tsx  | 42 -------------------
 3 files changed, 4 insertions(+), 47 deletions(-)

diff --git a/packages/polaris-viz/CHANGELOG.md b/packages/polaris-viz/CHANGELOG.md
index 4e5af7560..141c3b982 100644
--- a/packages/polaris-viz/CHANGELOG.md
+++ b/packages/polaris-viz/CHANGELOG.md
@@ -7,6 +7,10 @@ and adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
 
+### Fixed
+
+- Fixed issue in `<StackedArea />` where changing data series length would cause the chart to throw an error
+
 ### Changed
 
 - Removed main percentage label from `<FunnelChartNext />`
diff --git a/packages/polaris-viz/src/components/StackedAreaChart/components/StackedAreas/StackedAreas.tsx b/packages/polaris-viz/src/components/StackedAreaChart/components/StackedAreas/StackedAreas.tsx
index 0d39b14de..a9f656189 100644
--- a/packages/polaris-viz/src/components/StackedAreaChart/components/StackedAreas/StackedAreas.tsx
+++ b/packages/polaris-viz/src/components/StackedAreaChart/components/StackedAreas/StackedAreas.tsx
@@ -86,13 +86,8 @@ export function StackedAreas({
   return (
     <Fragment>
       {stackedValues.map((data, index) => {
-        const isSeriesLengthIncreasing =
-          previousStackedValues &&
-          previousStackedValues.length < stackedValues.length;
-
         const dataIsValidForAnimation =
           !previousStackedValues ||
-          isSeriesLengthIncreasing ||
           data.length === previousStackedValues[index]?.length;
 
         const AreaComponent = dataIsValidForAnimation ? AnimatedArea : Area;
diff --git a/packages/polaris-viz/src/components/StackedAreaChart/components/StackedAreas/tests/StackedAreas.test.tsx b/packages/polaris-viz/src/components/StackedAreaChart/components/StackedAreas/tests/StackedAreas.test.tsx
index 340b76701..e142fdc50 100644
--- a/packages/polaris-viz/src/components/StackedAreaChart/components/StackedAreas/tests/StackedAreas.test.tsx
+++ b/packages/polaris-viz/src/components/StackedAreaChart/components/StackedAreas/tests/StackedAreas.test.tsx
@@ -100,47 +100,5 @@ describe('<StackedAreas />', () => {
         duration: 100,
       });
     });
-
-    it('renders and animates when series length changes', () => {
-      const singleSeriesValues = [
-        [
-          [163, 269],
-          [0, 0],
-        ],
-      ] as StackedSeries[];
-
-      const stackedArea = mount(
-        <svg>
-          <StackedAreas
-            {...mockProps}
-            stackedValues={singleSeriesValues}
-            zeroLineValues={singleSeriesValues}
-          />
-        </svg>,
-      );
-
-      expect(stackedArea).toContainReactComponentTimes(AnimatedArea, 1);
-
-      // Update with two series
-      stackedArea.setProps({
-        children: (
-          <StackedAreas
-            {...mockProps}
-            stackedValues={mockStackedValues}
-            zeroLineValues={mockStackedValues}
-          />
-        ),
-      });
-
-      const stacks = stackedArea.findAll(AnimatedArea);
-
-      expect(stackedArea).toContainReactComponentTimes(AnimatedArea, 2);
-      expect(stacks[0]).toHaveReactProps({
-        duration: 275,
-      });
-      expect(stacks[1]).toHaveReactProps({
-        duration: 275,
-      });
-    });
   });
 });