gbuoy/test/data/graph.spec.ts

import { expect } from "chai"

import { colorGreedy, 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"]))
        })
    })

    describe("colorGreedy", () => {
        it("colors graph", () => {
            const g = createGraph((v, e) => {
                [0, 1, 2, 3, 4].forEach(i => v("x" + i, true))

                e("x0", "x1")
                e("x1", "x2")
                e("x2", "x3")
            })

            const coloring1 = colorGreedy(g, ["x0", "x1", "x2", "x3", "x4"])
            expect(coloring1.numColors).to.equal(2)

            const coloring2 = colorGreedy(g, ["x0", "x3", "x1", "x2", "x4"])
            expect(coloring2.numColors).to.equal(3)
        })
    })
})