revert previously deleted test case

Author: knite51

test/utils/url.spec.ts

@@ -365,6 +365,35 @@ describe("Url utils tests", () => {
     });
   });
 
+  describe("getPreviousPageUrl tests", () => {
+
+    test("returns correct previous page from request headers", () => {
+      req["rawHeaders"] = ["Referer", `http://host-name${config.WHO_IS_MAKING_FILING_URL}`];
+
+      const previousPage = urlUtils.getPreviousPageUrl(req, config.REGISTER_AN_OVERSEAS_ENTITY_URL);
+
+      // Check that the "http://host-name" absolute URL prefix has been stripped off when setting the previousPage URL
+      expect(previousPage).toEqual(config.WHO_IS_MAKING_FILING_URL);
+    });
+
+    test("does not return a potentially malicious previous page URL", () => {
+      req["rawHeaders"] = ["Referer", `http://host-name/illegal-path`];
+
+      const previousPage = urlUtils.getPreviousPageUrl(req, config.REGISTER_AN_OVERSEAS_ENTITY_URL);
+
+      // Check that the "http://host-name/illegal-path" url is not returned
+      expect(previousPage).toBeUndefined();
+    });
+
+    test("returns undefined if no url found in headers", () => {
+      req["rawHeaders"] = ["Referer", ""];
+
+      const previousPage = urlUtils.getPreviousPageUrl(req, config.REGISTER_AN_OVERSEAS_ENTITY_URL);
+
+      expect(previousPage).toBeUndefined();
+    });
+  });
+
   describe("getBackLinkUrl tests", () => {
     const urlWithEntityIds = "/transaction/:transactionId/submission/:submissionId/entity";
     const urlWithoutEntityIds = "/entity";