feat(packages/vue): add useLastChanged composable

packages/vue/src/composables/useLastChanged/index.test.ts

@@ -0,0 +1,50 @@
+import { ref, nextTick } from 'vue';
+import { describe, it, expect, vi } from 'vitest';
+import { useLastChanged } from '.';
+import { timestamp } from '@robonen/stdlib';
+
+describe('useLastChanged', () => {
+  it('should initialize with null if no initialValue is provided', () => {
+    const source = ref(0);
+    const lastChanged = useLastChanged(source);
+
+    expect(lastChanged.value).toBeNull();
+  });
+
+  it('should initialize with the provided initialValue', () => {
+    const source = ref(0);
+    const initialValue = 123456789;
+    const lastChanged = useLastChanged(source, { initialValue });
+
+    expect(lastChanged.value).toBe(initialValue);
+  });
+
+  it('should update the timestamp when the source changes', async () => {
+    const source = ref(0);
+    const lastChanged = useLastChanged(source);
+
+    const initialTimestamp = lastChanged.value;
+    source.value = 1;
+    await nextTick();
+
+    expect(lastChanged.value).not.toBe(initialTimestamp);
+    expect(lastChanged.value).toBeLessThanOrEqual(timestamp());
+  });
+
+  it('should update the timestamp immediately if immediate option is true', async () => {
+    const source = ref(0);
+    const lastChanged = useLastChanged(source, { immediate: true });
+
+    expect(lastChanged.value).toBeLessThanOrEqual(timestamp());
+  });
+
+  it('should not update the timestamp if the source does not change', async () => {
+    const source = ref(0);
+    const lastChanged = useLastChanged(source);
+
+    const initialTimestamp = lastChanged.value;
+    await nextTick();
+
+    expect(lastChanged.value).toBe(initialTimestamp);
+  });
+});