diff --git a/__snapshots__/ndate.spec.ts.snap b/__snapshots__/ndate.spec.ts.snap
index 5e8b663..3f6b499 100644
--- a/__snapshots__/ndate.spec.ts.snap
+++ b/__snapshots__/ndate.spec.ts.snap
@@ -1,15 +1,15 @@
 export const snapshot = {};
 
 snapshot[`show help 1`] = `
-"Usage: ndate [-] [--zero] [--date-style <full|long|medium|short|none>] [--time-style <full|long|medium|short|none>]
+"Usage: ndate [-] [--date <date>] [-d <date>] [--date-style <full|long|medium|short|none>]
 " +
-  "             [--hour-cycles <h11|h12|h23|h24|none>] [--time-zone <time-zone>] [--local <locale>]
+  "             [--time-style <full|long|medium|short|none>] [--hour-cycles <h11|h12|h23|h24|none>]
 " +
-  "             [--template <template>] [--json] [--sheet] [--utc] [--epoch] [--epoch-ms]
+  "             [--time-zone <time-zone>] [-tz <time-zone>] [--local <locale>] [-l <locale>]
 " +
-  "             [--date <date>] [--help] [-j] [-d <date>] [-l <locale>] [-tz <time-zone>]
+  "             [--template <template>] [--json] [-j] [--sheet] [--utc] [--epoch] [--epoch-ms]
 " +
-  "             [-z] [-h]
+  "             [--help] [-h] [--zero] [-z]
 "
 `;
 
diff --git a/lib/makeFlags.spec.ts b/lib/makeFlags.spec.ts
new file mode 100644
index 0000000..63038a3
--- /dev/null
+++ b/lib/makeFlags.spec.ts
@@ -0,0 +1,168 @@
+import {
+  assertArrayIncludes,
+  assertEquals,
+  assertInstanceOf,
+  assertObjectMatch,
+} from "https://deno.land/std@0.204.0/assert/mod.ts";
+import { makeFlags as makeFlags2 } from "../makeFlags.ts";
+
+Deno.test("should parse zero argument", () => {
+  assertEquals(makeFlags2([]).insertFinalNewLine, true);
+  assertEquals(makeFlags2(["-z"]).insertFinalNewLine, false);
+  assertEquals(makeFlags2(["--zero"]).insertFinalNewLine, false);
+});
+
+Deno.test("should parse date argument", () => {
+  assertInstanceOf(makeFlags2([]).date, Date);
+  assertEquals(
+    makeFlags2(["-d", "2024-04-02T05:23:05Z"]).date.toJSON(),
+    "2024-04-02T05:23:05.000Z",
+  );
+  assertEquals(
+    makeFlags2(["--date", "2024-04-02T05:23:05Z"]).date.toJSON(),
+    "2024-04-02T05:23:05.000Z",
+  );
+});
+
+Deno.test("should parse help argument", () => {
+  assertEquals(makeFlags2([]).showHelp, false);
+  assertEquals(makeFlags2(["-h"]).showHelp, true);
+  assertEquals(makeFlags2(["--help"]).showHelp, true);
+});
+
+Deno.test("should parse date-style argument", () => {
+  assertEquals(makeFlags2([]).dateStyle, "full");
+  assertEquals(makeFlags2(["--date-style", "other"]).dateStyle, "none");
+  assertEquals(makeFlags2(["--date-style", "medium"]).dateStyle, "medium");
+});
+
+Deno.test("should parse time-style argument", () => {
+  assertEquals(makeFlags2([]).timeStyle, "full");
+  assertEquals(makeFlags2(["--time-style", "other"]).timeStyle, "none");
+  assertEquals(makeFlags2(["--time-style", "medium"]).timeStyle, "medium");
+});
+
+Deno.test("should parse hour-cycles argument", () => {
+  assertEquals(makeFlags2([]).hourCycle, "none");
+  assertEquals(makeFlags2(["--hour-cycles", "h23"]).hourCycle, "h23");
+  assertEquals(makeFlags2(["--hour-cycles", "h12"]).hourCycle, "h12");
+});
+
+Deno.test("should parse time-zone argument", () => {
+  assertEquals(makeFlags2([]).timeZone, undefined);
+  assertEquals(
+    makeFlags2(["--time-zone", "America/Santiago"]).timeZone,
+    "America/Santiago",
+  );
+  assertEquals(
+    makeFlags2(["-tz", "America/Santiago"]).timeZone,
+    "America/Santiago",
+  );
+});
+
+Deno.test("should parse local argument", () => {
+  assertEquals(makeFlags2([]).local, undefined);
+  assertEquals(makeFlags2(["--local", "es-CL"]).local, "es-CL");
+  assertEquals(makeFlags2(["-l", "es-CL"]).local, "es-CL");
+});
+
+Deno.test("should parse template argument", () => {
+  assertEquals(makeFlags2([]).template, undefined);
+  assertEquals(makeFlags2(["--template", "hello"]).template, "hello");
+});
+
+Deno.test("should parse json argument", () => {
+  assertEquals(makeFlags2([]).outputAsJSON, false);
+  assertEquals(makeFlags2(["--json"]).outputAsJSON, true);
+  assertEquals(makeFlags2(["-j"]).outputAsJSON, true);
+});
+
+Deno.test("should parse sheet argument", () => {
+  assertEquals(makeFlags2([]).outputAsSheet, false);
+  assertEquals(makeFlags2(["--sheet"]).outputAsSheet, true);
+});
+
+Deno.test("should parse utc argument", () => {
+  assertEquals(makeFlags2([]).outputAsUTC, false);
+  assertEquals(makeFlags2(["--utc"]).outputAsUTC, true);
+});
+
+Deno.test("should parse epoch argument", () => {
+  assertEquals(makeFlags2([]).outputAsEpoch, false);
+  assertEquals(makeFlags2(["--epoch"]).outputAsEpoch, true);
+});
+
+Deno.test("should parse epoch-ms argument", () => {
+  assertEquals(makeFlags2([]).outputAsEpochMS, false);
+  assertEquals(makeFlags2(["--epoch-ms"]).outputAsEpochMS, true);
+});
+
+Deno.test("should parse hyphen argument", () => {
+  assertEquals(makeFlags2([]).stdinReadable, false);
+  assertEquals(makeFlags2(["-"]).stdinReadable, true);
+});
+
+Deno.test("should get the transformOptions field", () => {
+  const s = Array.from(Object.keys(makeFlags2([]).transformOptions));
+
+  assertArrayIncludes(s, [
+    "-",
+    "--zero",
+    "--date-style",
+    "--time-style",
+    "--hour-cycles",
+    "--time-zone",
+    "--local",
+    "--template",
+    "--json",
+    "--sheet",
+    "--utc",
+    "--epoch",
+    "--epoch-ms",
+    "--date",
+    "--help",
+    "-j",
+    "-d",
+    "-l",
+    "-tz",
+    "-z",
+    "-h",
+  ]);
+});
+
+Deno.test("should get the optionsLabels field", () => {
+  const s = makeFlags2([]).optionsLabels;
+
+  assertObjectMatch(s, {
+    "--date": {
+      label: "<date>",
+    },
+    "-d": {
+      label: "<date>",
+    },
+    "--date-style": {
+      label: "<full|long|medium|short|none>",
+    },
+    "--hour-cycles": {
+      label: "<h11|h12|h23|h24|none>",
+    },
+    "--local": {
+      label: "<locale>",
+    },
+    "-l": {
+      label: "<locale>",
+    },
+    "--template": {
+      label: "<template>",
+    },
+    "--time-style": {
+      label: "<full|long|medium|short|none>",
+    },
+    "--time-zone": {
+      label: "<time-zone>",
+    },
+    "-tz": {
+      label: "<time-zone>",
+    },
+  });
+});