test_that("basic adj lists work", {
    a = adj(2:3, NULL, 4:5, integer(0), 1)
    expect_length(a, 5)
    expect_true(is_adj(a))

    a = adj(1, 2, 3, self_loops = "remove")
    a_manual = adj:::new_adj(
        list(integer(0), integer(0), integer(0)),
        duplicates = "warn",
        self_loops = "error"
    )
    expect_identical(a, a_manual)
    expect_identical(a_manual, adj:::validate_adj(a_manual))
})

test_that("validate_adj works", {
    expect_error(validate_adj(5), "list")
    expect_error(
        validate_adj(structure(list(c(1L, 1L)), duplicates = "allow", self_loops = "bad")),
        "must be"
    )
    expect_error(
        validate_adj(structure(list(c(1L, 1L)), duplicates = "bad", self_loops = "allow")),
        "must be"
    )
    expect_silent(
        validate_adj(structure(
            list(2L, 1L),
            class = "adj",
            duplicates = "error",
            self_loops = "error"
        ))
    )
    expect_error(
        validate_adj(structure(
            list(2.0, 1.0),
            class = "adj",
            duplicates = "error",
            self_loops = "error"
        )),
        "integer"
    )
})

test_that("invalid adj lists error", {
    expect_warning(
        adj(konigsberg$bridge_to, ids = konigsberg$area, duplicates = "warn"),
        "Duplicate"
    )
    expect_error(
        adj(konigsberg$bridge_to, ids = konigsberg$area, duplicates = "error"),
        "Duplicate"
    )
})

test_that("koningsberg adj list works", {
    a = adj(konigsberg$bridge_to, ids = konigsberg$area, duplicates = "remove")
    expect_true(is_adj(a))
    expect_true(all(lengths(a) < 4))

    a = adj(konigsberg$bridge_to, ids = konigsberg$area, duplicates = "allow")
    expect_true(is_adj(a))
    expect_identical(adj_to_list(a, ids = konigsberg$area), konigsberg$bridge_to)
    expect_error(adj_to_list(a, ids = LETTERS[1:5]), "same")
    expect_error(adj(a, ids = LETTERS[c(1, 1, 2, 3)]), "unique")
    expect_error(adj(a, ids = LETTERS[c(1, 2, 3, 5)]), "match")
})

test_that("adj fails on invalid inputs", {
    expect_error(adj(2, "A"), 'list of integer vectors')
    expect_error(adj(2, 3), 'Out-of-bounds')
})