feat: add jest and initial tests for masking values

utils/maskvalue.test.ts

@@ -0,0 +1,22 @@
+import { describe, expect, test } from "@jest/globals"
+
+import { email, phone, text } from "./maskValue"
+
+describe("Mask value", () => {
+  test("masks e-mails properly", () => {
+    expect(email("test@example.com")).toBe("t***@e******.com")
+    expect(email("test@sub.example.com")).toBe("t***@s**.e******.com")
+    expect(email("test_no_atexample.com")).toBe("t********************")
+    expect(email("test_no_dot@examplecom")).toBe("t*********************")
+    expect(email("test_no_at_no_dot_com")).toBe("t********************")
+  })
+
+  test("masks phone number properly", () => {
+    expect(phone("0000000000")).toBe("********00")
+  })
+
+  test("masks text strings properly", () => {
+    expect(text("test")).toBe("t***")
+    expect(text("test.with.dot")).toBe("t************")
+  })
+})