diff --git a/tests/patterns.test.ts b/tests/patterns.test.ts
new file mode 100644
index 0000000..1975a70
--- /dev/null
+++ b/tests/patterns.test.ts
@@ -0,0 +1,135 @@
+import { masks } from "../src/index";
+import { test, expect } from "vitest";
+
+test("visa", () => {
+  const valid = [
+    "4123 4567 8912 3456",
+    "4123456789123",
+    "4123456789123456",
+  ];
+
+  const invalid = [
+    "5123 4567 8912 3456", // Starts with 5 (not Visa)
+    "4123 4567 8912", // 12 digits
+    "4123 4567 8912 345", // 15 digits
+    "4123 4567 8912 34567", // 17 digits
+  ];
+
+  valid.forEach((number) => {
+    expect(masks.visa.final.test(number.replace(/\s+/g, ""))).toBe(true);
+  });
+
+  invalid.forEach((number) => {
+    expect(masks.visa.final.test(number.replace(/\s+/g, ""))).toBe(false);
+  });
+});
+
+test("mastercard", () => {
+  const valid = [
+    "5123 4567 8912 3456",
+    "5123456789123456",
+  ];
+
+  const invalid = [
+    "4123 4567 8912 3456", // Starts with 4 (not MasterCard)
+    "5123 4567 8912", // 12 digits
+    "5123 4567 8912 34567", // 17 digits
+    "5123 4567 8912 345", // 15 digits
+  ];
+
+  valid.forEach((number) => {
+    expect(masks.mastercard.final.test(number.replace(/\s+/g, ""))).toBe(true);
+  });
+
+  invalid.forEach((number) => {
+    expect(masks.mastercard.final.test(number.replace(/\s+/g, ""))).toBe(false);
+  });
+});
+
+test("amex", () => {
+  const valid = [
+    "3714 4963 5398 431",
+    "378282246310005",
+  ];
+
+  const invalid = [
+    "4123 4567 8912 3456", // Starts with 4 (not Amex)
+    "3714 4963 5398", // 12 digits
+    "3714 4963 5398 4312", // 16 digits
+    "37828224631000", // 14 digits
+  ];
+
+  valid.forEach((number) => {
+    expect(masks.amex.final.test(number.replace(/\s+/g, ""))).toBe(true);
+  });
+
+  invalid.forEach((number) => {
+    expect(masks.amex.final.test(number.replace(/\s+/g, ""))).toBe(false);
+  });
+});
+
+test("discover", () => {
+  const valid = [
+    "6011 1111 1111 1117",
+    "6500 0000 0000 0000",
+  ];
+
+  const invalid = [
+    "4123 4567 8912 3456", // Starts with 4 (not Discover)
+    "6011 1111 1111", // 12 digits
+    "6011 1111 1111 11111", // 17 digits
+    "6500 0000 0000 000", // 15 digits
+  ];
+
+  valid.forEach((number) => {
+    expect(masks.discover.final.test(number.replace(/\s+/g, ""))).toBe(true);
+  });
+
+  invalid.forEach((number) => {
+    expect(masks.discover.final.test(number.replace(/\s+/g, ""))).toBe(false);
+  });
+});
+
+test("diners", () => {
+  const valid = [
+    "3000 0000 0000 04",
+    "3056 9309 0259 04",
+  ];
+
+  const invalid = [
+    "4123 4567 8912 3456", // Starts with 4 (not Diners Club)
+    "3000 0000 0000", // 12 digits
+    "3000 0000 0000 0456", // 16 digits
+    "3056 9309 0259 045", // 15 digits
+  ];
+
+  valid.forEach((number) => {
+    expect(masks.diners.final.test(number.replace(/\s+/g, ""))).toBe(true);
+  });
+
+  invalid.forEach((number) => {
+    expect(masks.diners.final.test(number.replace(/\s+/g, ""))).toBe(false);
+  });
+});
+
+test("jcb", () => {
+  const valid = [
+    "2131 1234 5678 123",
+    "3512 3456 7890 1234",
+  ];
+
+  const invalid = [
+    "4123 4567 8912 3456", // Starts with 4 (not JCB)
+    "2131 1234 5678", // 12 digits
+    "2131 1234 5678 12345", // 17 digits
+    "3512 3456 7890", // 12 digits
+  ];
+
+  valid.forEach((number) => {
+    expect(masks.jcb.final.test(number.replace(/\s+/g, ""))).toBe(true);
+  });
+
+  invalid.forEach((number) => {
+    expect(masks.jcb.final.test(number.replace(/\s+/g, ""))).toBe(false);
+  });
+});