add unit tests

src/__tests__/index.test.tsx

@@ -0,0 +1,112 @@
+import { vi } from "vitest";
+import { render, screen } from "@testing-library/react";
+import "@testing-library/jest-dom";
+import TimeAgo, { TimeAgoProps } from "../index.js";
+
+function setup(props: TimeAgoProps) {
+  render(
+    <div role="main">
+      <TimeAgo {...props} />
+    </div>
+  );
+  return screen.getByRole("main");
+}
+
+describe("TimeAgo", () => {
+  beforeAll(() => {
+    // this whole test suite is frozen in time. it's
+    // currently 11am UTC (11pm NZST) on June 6th, 2023.
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date("2023-06-06T11:00Z"));
+  });
+
+  describe("basic", () => {
+    it.each`
+      date                      | locale       | output
+      ${"2023-06-08"}           | ${"en"}      | ${"0 seconds ago"}
+      ${"2023-06-07"}           | ${"en"}      | ${"0 seconds ago"}
+      ${"2023-06-06"}           | ${"en"}      | ${"11 hours ago"}
+      ${"2019-06-06"}           | ${"en"}      | ${"4 years ago"}
+      ${"2019-06-06"}           | ${"mi-NZ"}   | ${"-4 y"}
+      ${"2019-06-06"}           | ${"de-LU"}   | ${"vor 4 Jahren"}
+      ${"2023-06-06T11:00:00Z"} | ${"de"}      | ${"vor 0 Sekunden"}
+      ${"2023-06-06T10:59:59Z"} | ${"de"}      | ${"vor 1 Sekunde"}
+      ${"2023-06-06T10:59:58Z"} | ${"de"}      | ${"vor 2 Sekunden"}
+      ${"2023-06-06T10:59:00Z"} | ${"fr"}      | ${"il y a 1 minute"}
+      ${"2023-06-06T10:00:00Z"} | ${"es"}      | ${"hace 1 hora"}
+      ${"2023-06-06T10:00:00Z"} | ${"zh-Hant"} | ${"1 小時前"}
+      ${"2023-06-06T10:00:00Z"} | ${"zh-Hans"} | ${"1小时前"}
+      ${"1989-09-01"}           | ${"sm"}      | ${"33 years ago" /* lang not supported */}
+      ${"1989-09-01"}           | ${"rrm"}     | ${"33 years ago" /* lang not supported */}
+    `(
+      "renders $date as $output in $locale",
+      async ({ date, locale, output }) => {
+        const div = setup({ date, locale });
+
+        expect(div).toHaveTextContent(output);
+      }
+    );
+  });
+
+  describe("hideSeconds", () => {
+    it.each`
+      date                      | output
+      ${"2023-06-08"}           | ${"1 minute ago"}
+      ${"2024-01-01"}           | ${"1 minute ago"}
+      ${"2023-06-06T11:00:00Z"} | ${"1 minute ago"}
+      ${"2023-06-06T10:59:59Z"} | ${"1 minute ago"}
+      ${"2023-06-06T10:59:58Z"} | ${"1 minute ago"}
+      ${"2023-06-06T10:59:01Z"} | ${"1 minute ago"}
+      ${"2023-06-06T10:59:00Z"} | ${"1 minute ago"}
+      ${"2023-06-06T10:58:59Z"} | ${"1 minute ago"}
+    `("renders $date as $output", ({ date, output }) => {
+      const div = setup({ date, hideSeconds: true });
+
+      expect(div).toHaveTextContent(output);
+    });
+  });
+
+  describe("roundStrategy", () => {
+    it.each`
+      date                   | roundStrategy | output
+      ${"2022-07-01"}        | ${"floor"}    | ${"vor 11 Monaten"}
+      ${"2022-07-01"}        | ${"round"}    | ${"vor 1 Jahr"}
+      ${"2023-06-01"}        | ${"floor"}    | ${"vor 5 Tagen"}
+      ${"2023-06-01"}        | ${"round"}    | ${"vor 5 Tagen"}
+      ${"2023-06-06T07:00Z"} | ${"floor"}    | ${"vor 4 Stunden"}
+      ${"2023-06-06T07:00Z"} | ${"round"}    | ${"vor 4 Stunden"}
+    `(
+      "renders $date as $output using $roundStrategy",
+      async ({ date, roundStrategy, output }) => {
+        const div = setup({ date, locale: "de-AT", roundStrategy });
+
+        expect(div).toHaveTextContent(output);
+      }
+    );
+
+    it.each`
+      date            | output
+      ${"2019"}       | ${"hace 5 año"}
+      ${"2023"}       | ${"hace 1 año"}
+      ${"2023-06-01"} | ${"hace 1 año"}
+      ${"2023-06-06"} | ${"hace 1 año"}
+      ${"2024"}       | ${"hace 0 segundos"}
+    `(
+      "doesn't crash if someone tries to use ceil with $date",
+      ({ date, output }) => {
+        // ceil is not a valid roundStrategy, typescript will enforce this
+        // at compile time, but nothing is stopping the user at runtime.
+
+        // so, let's test that it doesn't crash. The output can be bogus.
+        expect(
+          setup({
+            date,
+            locale: "es-419",
+            // @ts-expect-error -- typescript should not allow this
+            roundStrategy: "ceil",
+          })
+        ).toHaveTextContent(output);
+      }
+    );
+  });
+});