diff --git a/test/common/datetime/shift_date_range.test.ts b/test/common/datetime/shift_date_range.test.ts
new file mode 100644
index 000000000000..1caf7382f8e4
--- /dev/null
+++ b/test/common/datetime/shift_date_range.test.ts
@@ -0,0 +1,68 @@
+import { describe, it, expect } from "vitest";
+import { shiftDateRange } from "../../../src/common/datetime/calc_date";
+import {
+  NumberFormat,
+  TimeFormat,
+  FirstWeekday,
+  DateFormat,
+  TimeZone,
+} from "../../../src/data/translation";
+
+const mockConfig = {
+  time_zone: "America/New_York",
+};
+
+describe("shiftDateRange", () => {
+  const locale = {
+    language: "en",
+    number_format: NumberFormat.language,
+    time_format: TimeFormat.language,
+    date_format: DateFormat.language,
+    time_zone: TimeZone.local,
+    first_weekday: FirstWeekday.language,
+  };
+
+  it("shifts date range forward month", () => {
+    const startDate = new Date(2024, 0, 1);
+    const endDate = new Date(2024, 0, 31);
+    const result = shiftDateRange(startDate, endDate, true, locale, mockConfig);
+    expect(result.start).toEqual(new Date(2024, 1, 1));
+    expect(result.end).toEqual(new Date(2024, 1, 29, 23, 59, 59, 999));
+  });
+
+  it("shifts date range backward month", () => {
+    const startDate = new Date(2025, 0, 1);
+    const endDate = new Date(2025, 0, 31);
+    const result = shiftDateRange(
+      startDate,
+      endDate,
+      false,
+      locale,
+      mockConfig
+    );
+    expect(result.start).toEqual(new Date(2024, 11, 1));
+    expect(result.end).toEqual(new Date(2024, 11, 31, 23, 59, 59, 999));
+  });
+
+  it("shifts date range forward day", () => {
+    const startDate = new Date(2025, 0, 1);
+    const endDate = new Date(new Date(2025, 0, 1, 23, 59, 59, 999));
+    const result = shiftDateRange(startDate, endDate, true, locale, mockConfig);
+    expect(result.start).toEqual(new Date(2025, 0, 2));
+    expect(result.end).toEqual(new Date(2025, 0, 2, 23, 59, 59, 999));
+  });
+
+  it("shifts date range backward day", () => {
+    const startDate = new Date(2025, 0, 2);
+    const endDate = new Date(new Date(2025, 0, 2, 23, 59, 59, 999));
+    const result = shiftDateRange(
+      startDate,
+      endDate,
+      false,
+      locale,
+      mockConfig
+    );
+    expect(result.start).toEqual(new Date(2025, 0, 1));
+    expect(result.end).toEqual(new Date(2025, 0, 1, 23, 59, 59, 999));
+  });
+});