[Test Improver] Add unit tests for useInterval composable

shell/composables/__tests__/useInterval.test.ts

@@ -0,0 +1,119 @@
+import { defineComponent } from 'vue';
+import { mount } from '@vue/test-utils';
+import { useInterval } from '@shell/composables/useInterval';
+
+/**
+ * Mount a component that calls useInterval with the given fn and delay.
+ * Returns the wrapper so tests can unmount it to trigger onBeforeUnmount.
+ */
+function makeWrapper(fn: jest.Mock, delay: number) {
+  return mount(
+    defineComponent({
+      setup() {
+        useInterval(fn, delay);
+
+        return {};
+      },
+      template: '<div></div>',
+    })
+  );
+}
+
+describe('useInterval', () => {
+  beforeEach(() => {
+    jest.useFakeTimers();
+  });
+
+  afterEach(() => {
+    jest.useRealTimers();
+  });
+
+  describe('on mount', () => {
+    it('starts calling fn at the specified interval after mounting', () => {
+      const fn = jest.fn();
+      const wrapper = makeWrapper(fn, 1000);
+
+      expect(fn).not.toHaveBeenCalled();
+
+      jest.advanceTimersByTime(1000);
+      expect(fn).toHaveBeenCalledTimes(1);
+
+      jest.advanceTimersByTime(2000);
+      expect(fn).toHaveBeenCalledTimes(3);
+
+      wrapper.unmount();
+    });
+
+    it('calls fn with the correct delay', () => {
+      const fn = jest.fn();
+      const wrapper = makeWrapper(fn, 500);
+
+      jest.advanceTimersByTime(499);
+      expect(fn).not.toHaveBeenCalled();
+
+      jest.advanceTimersByTime(1);
+      expect(fn).toHaveBeenCalledTimes(1);
+
+      wrapper.unmount();
+    });
+  });
+
+  describe('on unmount', () => {
+    it('clears the interval so fn is no longer called after unmount', () => {
+      const fn = jest.fn();
+      const wrapper = makeWrapper(fn, 1000);
+
+      jest.advanceTimersByTime(1000);
+      expect(fn).toHaveBeenCalledTimes(1);
+
+      wrapper.unmount();
+
+      jest.advanceTimersByTime(5000);
+      // Should stay at 1 — interval was cleared on unmount
+      expect(fn).toHaveBeenCalledTimes(1);
+    });
+
+    it('does not throw when unmounting before interval fires', () => {
+      const fn = jest.fn();
+      const wrapper = makeWrapper(fn, 10000);
+
+      expect(fn).not.toHaveBeenCalled();
+      expect(() => wrapper.unmount()).not.toThrow();
+    });
+  });
+
+  describe('multiple instances', () => {
+    it('runs independent intervals for separate composable instances', () => {
+      const fn1 = jest.fn();
+      const fn2 = jest.fn();
+      const wrapper1 = makeWrapper(fn1, 1000);
+      const wrapper2 = makeWrapper(fn2, 2000);
+
+      jest.advanceTimersByTime(2000);
+      expect(fn1).toHaveBeenCalledTimes(2);
+      expect(fn2).toHaveBeenCalledTimes(1);
+
+      wrapper1.unmount();
+      wrapper2.unmount();
+    });
+
+    it('stopping one instance does not affect the other', () => {
+      const fn1 = jest.fn();
+      const fn2 = jest.fn();
+      const wrapper1 = makeWrapper(fn1, 1000);
+      const wrapper2 = makeWrapper(fn2, 1000);
+
+      jest.advanceTimersByTime(1000);
+      expect(fn1).toHaveBeenCalledTimes(1);
+      expect(fn2).toHaveBeenCalledTimes(1);
+
+      wrapper1.unmount();
+
+      jest.advanceTimersByTime(2000);
+      expect(fn1).toHaveBeenCalledTimes(1);
+      expect(fn2).toHaveBeenCalledTimes(3);
+
+      wrapper2.unmount();
+    });
+  });
+});