sj-freitas/forofa

const { first } = require("./../first");

describe("first function", () => {
  it("Gets the first value if no condition is present", () => {
    const value = first([1, 2, 3]);

    expect(value).toEqual(1);
  });

  it("Throws an exception if there are no values", () => {
    const firstOnEmptyIterable = () => first([]);

    expect(firstOnEmptyIterable).toThrow(Error);
    expect(firstOnEmptyIterable).toThrow(
      "Sequence contains no matching elements"
    );
  });

  it("Gets the first item that fills in the condition", () => {
    const value = first([1, 2, 3], t => t % 2 === 0);

    expect(value).toEqual(2);
  });
});