import { expect } from "chai"

import { createGraph, neighbors, vertices } from "../../lib/data/graph"

const g = createGraph((v, e) => {
    v("a", true)
    v("b", true)
    v("c", true)
    v("d", true)

    e("a", "b")
    e("a", "c")
})

const empty = createGraph((v, e) => { })

describe("graph", () => {
    describe("neighbors", () => {
        it("returns neighbors of vertex", () => {
            const ns = neighbors(g, "a")
            expect(ns).to.deep.equal(new Set(["b", "c"]))
        })

        it("returns empty set when vertex has no neighbors", () => {
            const ns = neighbors(g, "d")
            expect(ns).to.deep.equal(new Set())
        })

        it("throw on invalid vertex", () => {
            expect(() => neighbors(empty, "x")).to.throw()
        })
    })

    describe("vertices", () => {
        it("return all vertices for a graph", () => {
            const vs = vertices(g)
            expect(vs).to.deep.equal(new Set(["a", "b", "c", "d"]))
        })
    })
})