import Testing

@testable import Photochk

@Suite("UnionFind")
struct UnionFindTests {
    @Test("結合していない要素はそれぞれ単独の成分になる")
    func isolatedElements() {
        var uf = UnionFind(count: 4)
        let components = uf.components().map { $0.sorted() }.sorted { $0[0] < $1[0] }
        #expect(components == [[0], [1], [2], [3]])
    }

    @Test("推移的に結合した要素は1つの成分にまとまる")
    func transitiveMerge() {
        var uf = UnionFind(count: 5)
        uf.union(0, 1)
        uf.union(1, 2)
        uf.union(3, 4)

        let components = uf.components().map { $0.sorted() }.sorted { $0[0] < $1[0] }
        #expect(components == [[0, 1, 2], [3, 4]])
    }

    @Test("同じ成分をもう一度 union しても何も変わらない")
    func repeatedUnion() {
        var uf = UnionFind(count: 3)
        #expect(uf.union(0, 1) == true)
        #expect(uf.union(1, 0) == false)
        #expect(uf.find(0) == uf.find(1))
        #expect(uf.find(0) != uf.find(2))
    }
}