[EuiTextTruncate] Fix timeout clean-up when component unmounts

changelogs/upcoming/7495.md

@@ -0,0 +1,3 @@
+**Bug fixes**
+
+- Fixed `EuiTextTruncate` component to clean up timer from side effect on unmount

src/components/text_truncate/text_truncate.test.tsx

@@ -38,18 +38,51 @@ describe('EuiTextTruncate', () => {
     expect(container.firstChild).toMatchSnapshot();
   });
 
-  it('allows delaying truncation calculation by `calculationDelayMs`', () => {
-    jest.useFakeTimers();
+  describe('calculationDelayMs', () => {
+    beforeAll(jest.useFakeTimers);
+    afterAll(jest.useRealTimers);
 
-    const { queryByTestSubject } = render(
-      <EuiTextTruncate {...props} width={0} calculationDelayMs={50} />
-    );
-    expect(queryByTestSubject('truncatedText')).not.toBeInTheDocument();
+    it('allows delaying truncation calculation by the specified duration', () => {
+      const { queryByTestSubject } = render(
+        <EuiTextTruncate {...props} width={0} calculationDelayMs={50} />
+      );
+      expect(queryByTestSubject('truncatedText')).not.toBeInTheDocument();
+
+      act(() => jest.advanceTimersByTime(50));
+      expect(queryByTestSubject('truncatedText')).toBeInTheDocument();
+    });
+
+    it('sets and clears the timeout on update or unmount', () => {
+      const clearTimeoutSpy = jest.spyOn(window, 'clearTimeout');
+
+      const { unmount, rerender } = render(
+        <EuiTextTruncate {...props} width={0} calculationDelayMs={50} />
+      );
+      expect(clearTimeoutSpy).toHaveBeenCalledTimes(0);
 
-    act(() => jest.advanceTimersByTime(50));
-    expect(queryByTestSubject('truncatedText')).toBeInTheDocument();
+      rerender(
+        <EuiTextTruncate {...props} width={0} calculationDelayMs={100} />
+      );
+      expect(clearTimeoutSpy).toHaveBeenCalledTimes(1);
+      expect(clearTimeoutSpy).toHaveBeenLastCalledWith(expect.any(Number));
+
+      unmount();
+      expect(clearTimeoutSpy).toHaveBeenCalledTimes(2);
+      expect(clearTimeoutSpy).toHaveBeenLastCalledWith(expect.any(Number));
+    });
+
+    it('does not set or clear a timeout if a duration is not passed', () => {
+      const setTimeoutSpy = jest.spyOn(window, 'setTimeout');
+      const clearTimeoutSpy = jest.spyOn(window, 'clearTimeout');
 
-    jest.useRealTimers();
+      const { unmount } = render(
+        <EuiTextTruncate {...props} width={0} calculationDelayMs={0} />
+      );
+
+      expect(setTimeoutSpy).not.toHaveBeenCalled();
+      unmount();
+      expect(clearTimeoutSpy).not.toHaveBeenCalled();
+    });
   });
 
   describe('resize observer', () => {

src/components/text_truncate/text_truncate.tsx

@@ -139,7 +139,8 @@ const EuiTextTruncateWithWidth: FunctionComponent<
   const [ready, setReady] = useState(!calculationDelayMs);
   useEffect(() => {
     if (calculationDelayMs) {
-      setTimeout(() => setReady(true), calculationDelayMs);
+      const timerId = setTimeout(() => setReady(true), calculationDelayMs);
+      return () => clearTimeout(timerId);
     }
   }, [calculationDelayMs]);