From 6721aa4c3458ced6bad180648ea071f70b39745d Mon Sep 17 00:00:00 2001
From: Bernardo Sunderhus <bernardo.sunderhus@gmail.com>
Date: Tue, 25 Aug 2026 09:42:16 +0200
Subject: [PATCH] test: cover overflow menu convergence loop (#36612)

---
 .../src/overflowManager.test.ts               | 45 ++++++++++
 .../library/src/Overflow.cy.tsx               | 83 ++++++++++++++++++-
 2 files changed, 127 insertions(+), 1 deletion(-)

diff --git a/packages/react-components/priority-overflow/src/overflowManager.test.ts b/packages/react-components/priority-overflow/src/overflowManager.test.ts
index 70299140d146c..3be8a99ca9fcd 100644
--- a/packages/react-components/priority-overflow/src/overflowManager.test.ts
+++ b/packages/react-components/priority-overflow/src/overflowManager.test.ts
@@ -304,6 +304,51 @@ describe('overflowManager', () => {
     expect(getVisibleIds(manager)).toEqual(['a', 'b']);
   });
 
+  it('should converge when a conditional overflow menu changes item widths', () => {
+    const container = createContainer(110);
+    const menu = createElementWithSize('button', 30);
+    const invisibleItemCounts: number[] = [];
+    let menuAttached = false;
+
+    const manager = createOverflowManager(
+      createObserveOptions({
+        onUpdateOverflow: () => {
+          const invisibleItemCount = manager.getSnapshot().invisibleItemCount;
+          invisibleItemCounts.push(invisibleItemCount);
+
+          // Cap a regression so this test fails with the oscillating states instead of recursing indefinitely.
+          if (invisibleItemCounts.length >= 6) {
+            return;
+          }
+
+          if (invisibleItemCount > 0 && !menuAttached) {
+            menuAttached = true;
+            manager.addOverflowMenu(menu);
+          } else if (invisibleItemCount === 0 && menuAttached) {
+            menuAttached = false;
+            manager.removeOverflowMenu();
+          }
+        },
+      }),
+    );
+
+    const createResponsiveItem = () => {
+      const item = document.createElement('button');
+      Object.defineProperty(item, 'offsetWidth', {
+        configurable: true,
+        get: () => (menuAttached ? 35 : 60),
+      });
+      return item;
+    };
+
+    manager.addItem({ element: createResponsiveItem(), id: 'a', priority: 1 });
+    manager.addItem({ element: createResponsiveItem(), id: 'b', priority: 0 });
+    manager.observe(container, { forceUpdate: true });
+
+    expect(invisibleItemCounts).toEqual([1, 0]);
+    expect(getVisibleIds(manager)).toEqual(['a', 'b']);
+  });
+
   it('should recompute when the overflow menu is removed with hidden items', () => {
     const manager = createOverflowManager(createObserveOptions());
     const container = createContainer(140);
diff --git a/packages/react-components/react-overflow/library/src/Overflow.cy.tsx b/packages/react-components/react-overflow/library/src/Overflow.cy.tsx
index faa43c2931366..278343ce588b7 100644
--- a/packages/react-components/react-overflow/library/src/Overflow.cy.tsx
+++ b/packages/react-components/react-overflow/library/src/Overflow.cy.tsx
@@ -108,7 +108,7 @@ const Menu: React.FC<{ width?: number }> = ({ width }) => {
   // No need to actually render a menu, we're testing state
   return (
     <>
-      <button {...selector} ref={ref} style={{ width: width ?? 50, height: 50 }}>
+      <button {...selector} ref={ref} style={{ width: width ?? 50, minWidth: width, height: 50 }}>
         +{overflowCount}
       </button>
       <Portal>
@@ -254,6 +254,87 @@ describe('Overflow', () => {
     });
   });
 
+  it('should keep the menu visible when one phone number overflows next to a divider', () => {
+    cy.on('uncaught:exception', error => {
+      if (error.message.includes('ResizeObserver loop completed with undelivered notifications')) {
+        return false;
+      }
+    });
+
+    const PhoneNumbers = () => {
+      const [width, setWidth] = React.useState(280);
+
+      return (
+        <>
+          {[40, 180, 250, 280].map(nextWidth => (
+            <button key={nextWidth} data-test-width={nextWidth} onClick={() => setWidth(nextWidth)}>
+              {nextWidth}
+            </button>
+          ))}
+          <Container size={width} padding={10}>
+            <OverflowItem id="primary-phone" groupId="primary-phone-group" priority={1}>
+              <a
+                {...{ [selectors.item]: 'primary-phone' }}
+                href="tel:+4790981948"
+                style={{ display: 'block', flexShrink: 0, overflow: 'hidden', width: 120 }}
+              >
+                +4790981948
+              </a>
+            </OverflowItem>
+            <OverflowDivider groupId="primary-phone-group">
+              <div
+                {...{ [selectors.divider]: 'primary-phone-group' }}
+                style={{ flexShrink: 0, width: 8 }}
+                aria-hidden="true"
+              >
+                •
+              </div>
+            </OverflowDivider>
+            <OverflowItem id="secondary-phone" priority={0}>
+              <a
+                {...{ [selectors.item]: 'secondary-phone' }}
+                href="tel:+47 (2) 3011302"
+                style={{ display: 'block', flexShrink: 0, overflow: 'hidden', width: 140 }}
+              >
+                +47 (2) 3011302
+              </a>
+            </OverflowItem>
+            <Menu width={36} />
+          </Container>
+        </>
+      );
+    };
+
+    const setPhoneContainerWidth = (width: number) => {
+      cy.get(`[data-test-width="${width}"]`).click();
+    };
+
+    mount(<PhoneNumbers />);
+    cy.get(`[${selectors.container}]`).should('have.css', 'width', '280px');
+    cy.window().then(win => new Cypress.Promise(resolve => win.requestAnimationFrame(() => resolve())));
+
+    setPhoneContainerWidth(40);
+    cy.get(`[${selectors.menu}]`).should('have.text', '+2');
+
+    setPhoneContainerWidth(180);
+    cy.get(`[${selectors.item}="primary-phone"]`).should('not.have.attr', 'data-overflowing');
+    cy.get(`[${selectors.divider}="primary-phone-group"]`).should('not.have.attr', 'data-overflowing');
+    cy.get(`[${selectors.item}="secondary-phone"]`).should('have.attr', 'data-overflowing');
+    cy.get(`[${selectors.menu}]`).should('have.text', '+1');
+
+    setPhoneContainerWidth(250);
+    cy.get(`[${selectors.item}="primary-phone"]`).should('not.have.attr', 'data-overflowing');
+    cy.get(`[${selectors.divider}="primary-phone-group"]`).should('not.have.attr', 'data-overflowing');
+    cy.get(`[${selectors.item}="secondary-phone"]`).should('have.attr', 'data-overflowing');
+    cy.get(`[${selectors.menu}]`).should('have.text', '+1');
+
+    setPhoneContainerWidth(280);
+    cy.get(`[${selectors.item}="primary-phone"]`).should('not.have.attr', 'data-overflowing');
+    cy.get(`[${selectors.divider}="primary-phone-group"]`).should('not.have.attr', 'data-overflowing');
+    cy.get(`[${selectors.item}="secondary-phone"]`).should('not.have.attr', 'data-overflowing');
+    cy.get(`[${selectors.menu}]`).should('not.exist');
+  });
+
   it(`should overflow items when there's more than one child element`, () => {
     const mapHelper = new Array(10).fill(0).map((_, i) => i);
     const overflowElementIndex = 6;