test_that("HTTP HEAD & synchronous then", {
  do <- function() {
    http_head(http$url("/"))$then(function(value) value$status_code)$then(
      function(x) expect_equal(x, 200)
    )
  }
  synchronise(do())
})

test_that("HTTP HEAD & async then", {
  do <- function() {
    http_head(http$url("/"))$then(function(value) http_get(value$url))$then(
      function(value) expect_equal(value$status_code, 200)
    )
  }
  synchronise(do())
})

test_that("HTTP HEAD & async then & sync then", {
  do <- function() {
    http_head(http$url("/"))$then(function(value) http_get(value$url))$then(
      function(value) value$status_code
    )$then(function(value) expect_equal(value, 200))
  }
  synchronise(do())
})

test_that("then for fulfilled", {
  do <- async(function() {
    dx <- http_head(http$url("/status/404"))
    dx2 <- http_head(http$url("/status/404"))
    dx$then(function() {
      dx2$then(function(value) value$status_code)$then(
        function(value) expect_equal(value, 404)
      )
    })
  })
  synchronise(do())
})

test_that("multiple then clauses are not allowed", {
  do <- async(function() {
    dx <- delay(1 / 1000)
    dx$then(function() 1)
    dx$then(function() 2)
  })

  err <- tryCatch(synchronise(do()), error = identity)
  expect_s3_class(err, "async_rejected")
  expect_match(conditionMessage(err), "already owned")
})

test_that("compact function notation", {
  do <- function() {
    http_head(http$url("/"))$then(function(.) http_get(.$url))$then(
      function(.) .$status_code
    )$then(function(.) expect_equal(., 200))
  }
  synchronise(do())
})

test_that("embedded then", {
  add1 <- function(n) {
    n
    delay(10 / 1000)$then(function(value) n + 1)
  }
  mul3 <- function(n) {
    n
    delay(10 / 1000)$then(function(value) n * 3)
  }

  do <- function() {
    add1(4)$then(mul3)$then(function(.) expect_equal(., 15))
  }
  synchronise(do())
})

test_that("more embedded thens", {
  steps <- numeric()
  do <- function() {
    async(function() steps <<- c(steps, 1))()$then(function() {
      async_constant()$then(function() steps <<- c(steps, 2))$then(
        function() steps <<- c(steps, 3)
      )
    })$then(function() {
      async_constant()$then(function() steps <<- c(steps, 4))$then(
        function() steps <<- c(steps, 5)
      )
    })$then(function() steps <<- c(steps, 6))
  }
  synchronise(do())
  expect_equal(steps, 1:6)
})