describe("Ops arithmetic", {
    describe("Container", {
        test_that("arithmetic operations work for Container objects", {
            # Addition
            co <- container(1, 2)
            expect_equal(co + container(), co)
            expect_equal(container() + co, co)
            expect_equal(co + list(), co)
            expect_equal(list() + co, co)
            expect_equal(co + 1, container(1, 2, 1))
            expect_equal(1 + co, container(1, 1, 2))
            expect_equal(1:3 + co, container(1, 2, 3, 1, 2))
            expect_equal(co + co, container(1, 2, 1, 2))

            # Subtraction
            co <- container(1L, 2L, 2L, 3L)
            expect_equal(co - container(), co)
            expect_equal(container() - co, container())
            expect_equal(co - co, container())
            expect_equal(co - list(), co)
            expect_equal(list() - co, container())
            expect_equal(co - 1L, container(2, 2, 3))
            expect_equal(1L - co, container())
            expect_equal(c(1L, 2L, 2L, 3L, 1L) - co, container(1))
        })
    })

    describe("Deque", {
        test_that("arithmetic operations work for Deque objects", {
            d <- deque(3, 2, 1)
            expect_equal(d + deque(), d)
            expect_equal(deque() + d, d)
            expect_equal(d + list(), d)
            expect_equal(list() + d, d)
            expect_equal(d + 1, deque(3, 2, 1, 1))
            expect_equal(1 + d, deque(1, 3, 2, 1))
            expect_equal(1:4 + d, deque(3, 2, 1, 4, 3, 2, 1))
            expect_equal(d + d, deque(3, 2, 1, 3, 2, 1))

            expect_equal(d - 1:4, deque(2))
            expect_equal(1:4 - d, deque(4))
        })
    })

    describe("Set", {
        test_that("arithmetic operations work for Set objects", {
            # Addition
            x <- setnew(1, 2,    "1", "2")
            y <- setnew(   2, 3,      "2", "3")
            expect_equal(x + x, x)
            expect_equal(x + setnew(), x)
            expect_equal(setnew() + x, x)
            expect_equal(x + list(), x)
            expect_equal(list() + x, x)
            expect_false((x + y) == (y + x))

            # Subtraction
            x <- setnew(1, 2,    "1", "2")
            y <- setnew(   2, 3,      "2", "3")
            expect_equal(x - x, setnew())
            expect_equal(x - setnew(), x)
            expect_equal(setnew() - x, setnew())
            expect_equal(x - list(), x)
            expect_equal(list() - x, setnew())
            expect_true(x - y != y - x)
        })
    })

    describe("Dict", {
        test_that("arithmetic operations work for Dict objects", {
            # x + y updates x by y
            x <- dict(a = 1, b = 2)
            y <- dict(       b = 9, c = 1)
            expect_equal(x + x, x)
            expect_equal(x + dict(), x)
            expect_equal(dict() + x, x)
            expect_equal(x + list(), x)
            expect_equal(list() + x, x)
            expect_equal(x + y, dict(a = 1, b = 9, c = 1))
            expect_equal(y + x, dict(a = 1, b = 2, c = 1))
            expect_equal(x + as.list(y), dict(a = 1, b = 9, c = 1))
            expect_true(isTRUE(all.equal(x + y, x + y)))
            expect_false(isTRUE(all.equal(x + y, y + x)))

            # x - y returns a copy of x with all `y` keys being discarded
            x <- dict(a = 1, b = 2)
            y <- dict(       b = 9, c = 1)
            expect_equal(x - x, dict())
            expect_equal(x - dict(), x)
            expect_equal(x - as.list(x), dict())
            expect_equal(dict() - x, dict())
            expect_equal(x - list(), x)
            expect_equal(list() - x, dict())
            expect_equal(x - y, dict(a = 1))
            expect_equal(x - as.list(y), dict(a = 1))
            expect_equal(y - x, dict(c = 1))
            expect_equal(y - as.list(x), dict(c = 1))
        })
    })
})