VIA-629 AJ/EO Move getNow() to utils and add tests

Author: ankur-jain-nhs

src/utils/date.test.ts

@@ -1,5 +1,7 @@
-import { UtcDateFromStringSchema, UtcDateTimeFromStringSchema } from "@src/utils/date";
-import { calculateAge } from "@src/utils/date";
+import { UtcDateFromStringSchema, UtcDateTimeFromStringSchema, calculateAge, getNow } from "@src/utils/date";
+import { headers } from "next/headers";
+
+jest.mock("next/headers");
 
 describe("utils-date", () => {
   describe("UtcDateFromStringSchema", () => {
@@ -64,6 +66,7 @@ describe("utils-date", () => {
       }).toThrow();
     });
   });
+
   describe("calculateAge", () => {
     beforeAll(() => {
       jest.useFakeTimers();
@@ -117,4 +120,41 @@ describe("utils-date", () => {
       }).toThrow();
     });
   });
+
+  describe("getNow", () => {
+    const fakeDateInSystem = "2000-01-01T01:01:01Z";
+    const fakeDateInHeader = "1212-12-12T12:12:12Z";
+
+    beforeEach(() => {
+      jest.useFakeTimers();
+      jest.setSystemTime(new Date(fakeDateInSystem));
+    });
+
+    it("should return current date by default", async () => {
+      expect(await getNow()).toEqual(new Date(fakeDateInSystem));
+    });
+
+    it("should return date set in the header, when it is valid", async () => {
+      const mockHeaders = {
+        get: jest.fn(() => {
+          return fakeDateInHeader;
+        }),
+      };
+      (headers as jest.Mock).mockResolvedValue(mockHeaders);
+
+      expect(await getNow()).toEqual(new Date(fakeDateInHeader));
+    });
+
+    it("should return current date when date set in the header is malformed", async () => {
+      const fakeDateInHeaderInvalid = "invalid-date";
+      const mockHeaders = {
+        get: jest.fn(() => {
+          return fakeDateInHeaderInvalid;
+        }),
+      };
+      (headers as jest.Mock).mockResolvedValue(mockHeaders);
+
+      expect(await getNow()).toEqual(new Date(fakeDateInSystem));
+    });
+  });
 });

src/utils/date.ts

@@ -1,5 +1,6 @@
 import { Age } from "@src/utils/auth/types";
 import { differenceInYears } from "date-fns";
+import { headers } from "next/headers";
 import { z } from "zod";
 
 const UtcDateFromStringSchema = z
@@ -38,4 +39,13 @@ const calculateAge = (date: string): Age => {
   return differenceInYears(today, birthDate) as Age;
 };
 
-export { UtcDateFromStringSchema, UtcDateTimeFromStringSchema, calculateAge };
+const getNow = async (): Promise<Date> => {
+  try {
+    const headersList = await headers();
+    return UtcDateTimeFromStringSchema.safeParse(headersList.get("x-e2e-datetime")).data ?? new Date();
+  } catch {
+    return new Date();
+  }
+};
+
+export { UtcDateFromStringSchema, UtcDateTimeFromStringSchema, calculateAge, getNow };