import { merge } from "./merge.js";

describe("merge", () => {
    it("merges two objects", () => {
        merge({ a: true }, { b: false }).must.eql({
            a: true,
            b: false,
        });
        merge({ a: true }, { a: false }).must.eql({
            a: false,
        });
        merge({ c: true }, { a: undefined, c: undefined }).must.eql({
            a: undefined,
            c: undefined,
        });
    });

    it("merges three objects", () => {
        merge({ a: true }, { b: false }, { c: "maybe" }).must.eql({
            a: true,
            b: false,
            c: "maybe",
        });
        merge({ a: true }, { a: false }, { a: true }).must.eql({
            a: true,
        });
        merge({ c: true }, { a: undefined, c: undefined }, { c: null, a: false }).must.eql({
            a: false,
            c: null,
        });
    });

    it("allows to unset value", () => {
        const result = merge({ c: true }, { c: merge.UNSET });
        result.must.not.have.property("c");
        result.must.eql({});
    });

    it("allows to overwrite unset value", () => {
        const result = merge({ c: true }, { c: merge.UNSET }, { c: true });
        result.must.eql({ c: true });
    });

    it("rejects arrays", () => {
        (() => merge({ c: true }, { c: merge.UNSET }, { c: true }, [])).must.throw(TypeError);
    });

    it("rejects primitive types", () => {
        (() => merge({ c: true }, { c: merge.UNSET }, { c: true }, "string")).must.throw(TypeError);
        (() => merge({ c: true }, { c: merge.UNSET }, { c: true }, 555)).must.throw(TypeError);
        (() => merge({ c: true }, { c: merge.UNSET }, { c: true }, false)).must.throw(TypeError);
        (() => merge({ c: true }, { c: merge.UNSET }, { c: true }, Symbol("hi"))).must.throw(TypeError);
    });

    it("rejects functions", () => {
        (() => merge({ c: true }, { c: merge.UNSET }, { c: true }, () => "hi")).must.throw(TypeError);
    });

    it("ignores nil", () => {
        (() => merge({ c: true }, { c: merge.UNSET }, { c: true }, undefined, null)).must.not.throw();
        merge({ c: true }, { c: merge.UNSET }, { c: true }, undefined, null).must.eql({
            c: true,
        });
    });
});