@applicaster/zapp-react-native-utils/utils/__tests__/startsWith.test.ts

Applicaster Zapp React Native utilities package

import { startsWith } from "../startsWith";

describe("startsWith", () => {
  it("returns false when str is null", () => {
    expect(startsWith("a", null)).toBe(false);
  });

  it("returns false when str is undefined", () => {
    expect(startsWith("a", undefined)).toBe(false);
  });

  it("returns true when string starts with target", () => {
    expect(startsWith("he", "hello")).toBe(true);
    expect(startsWith("", "hello")).toBe(true); // empty target always matches
  });

  it("returns false when string does not start with target", () => {
    expect(startsWith("yo", "hello")).toBe(false);
  });

  it("works with single character target", () => {
    expect(startsWith("h", "hello")).toBe(true);
    expect(startsWith("x", "hello")).toBe(false);
  });

  it("is case-sensitive", () => {
    expect(startsWith("He", "hello")).toBe(false);
    expect(startsWith("he", "hello")).toBe(true);
  });
});