Failure test case for getUserLang()

webpack/__tests__/i18next_failure_tests.ts

@@ -0,0 +1,29 @@
+jest.mock("axios", () => {
+  return {
+    default: {
+      get: jest.fn((_url: string) => {
+        return Promise.reject("Simulated failure");
+      })
+    }
+  };
+});
+
+import { generateUrl, getUserLang } from "../i18n";
+import axios from "axios";
+
+const LANG_CODE = "ab_CD"; // Intentionally non-existent lang code.
+
+describe("getUserLang", () => {
+  it("defaults to `en` when failure occurs", (done) => {
+    getUserLang(LANG_CODE)
+      .then((result) => {
+        expect(axios.get).toHaveBeenCalled();
+        expect(axios.get).toHaveBeenCalledWith(generateUrl(LANG_CODE));
+        expect(result).toEqual("en");
+        done();
+      })
+      .catch((x) => {
+        fail(x.message);
+      });
+  });
+});