import removeNonDigitCharacters from "./removeNonDigitCharacters";

describe("removeNonDigitCharacters", () => {
  it("should return only the numbers present in a string containing both numbers and letters", () => {
    const output = removeNonDigitCharacters("cyan9");
    expect(output).toEqual("9");
  });

  it("should return only the numbers present in a string containing only numbers", () => {
    const output = removeNonDigitCharacters("9");
    expect(output).toEqual("9");
  });

  it("should return an empty string when passed a string that contains no numbers", () => {
    const output = removeNonDigitCharacters("cyan");
    expect(output).toEqual("");
  });
});