rxTest({
  mod <- rxode2({
    a <- 6
    b <- 0.6
    d / dt(intestine) <- -a * intestine
    d / dt(blood) <- a * intestine - b * blood
  })

  mod2 <- rxode2({
    a <- 6
    b <- 0.6
    d / dt(intestine) <- -a * intestine
    f(intestine) <- 2
    d / dt(blood) <- a * intestine - b * blood
  })

  mod4 <- rxode2({
    a <- 6
    b <- 0.6
    d / dt(intestine) <- -a * intestine
    f(intestine) <- 0.5
    d / dt(blood) <- a * intestine - b * blood
  })

  mod5 <- rxode2({
    a <- 6
    b <- 0.6
    f <- 1
    d / dt(intestine) <- -a * intestine
    f(intestine) <- f
    d / dt(blood) <- a * intestine - b * blood
  })

  ms <- c("liblsoda", "lsoda", "dop853")
  for (m in ms) {
    et <- eventTable(time.units = "days")
    et$add.sampling(seq(0, 10, by = 1 / 24))
    et$add.dosing(
      dose = 2 / 24, strt.time = 0,
      nbr.doses = 10, dosing.interval = 1
    )

    solve1 <- solve(mod, et, method = m)
    solve2 <- solve(mod2, et, method = m)
    test_that(sprintf("Bioavaibility changes dose (%s)", m), {
      expect_false(all(solve1$intestine == solve2$intestine))
      expect_false(all(solve1$blood == solve2$blood))
    })


    et <- eventTable(time.units = "days")
    et$add.sampling(seq(0, 10, by = 1 / 24))
    et$add.dosing(
      dose = 2 / 24 * 2, strt.time = 0,
      nbr.doses = 10, dosing.interval = 1
    )

    solve3 <- solve(mod, et, method = m)
    test_that(sprintf("F=2 is equivalent to doubling dosing (%s)", m), {
      expect_equal(solve2$intestine, solve3$intestine)
      expect_equal(solve2$blood, solve3$blood)
    })

    et <- eventTable(time.units = "days")
    et$add.sampling(seq(0, 10, by = 1 / 24))
    et$add.dosing(
      dose = 2 / 24 * 0.5, strt.time = 0,
      nbr.doses = 10, dosing.interval = 1
    )

    solve4a <- solve(mod, et, method = m)

    et <- eventTable(time.units = "days")
    et$add.sampling(seq(0, 10, by = 1 / 24))
    et$add.dosing(
      dose = 2 / 24, strt.time = 0,
      nbr.doses = 10, dosing.interval = 1
    )
    test_that(sprintf("F=0.5 is equivalent to halving the dose (%s)", m), {
      solve4b <- solve(mod4, et, method = m)

      expect_equal(solve4a$intestine, solve4b$intestine)
      expect_equal(solve4a$blood, solve4b$blood)
    })

    test_that(sprintf("F=0.5 works with parameter-based F (%s)", m), {
      solve5a <- solve(mod5, et, c(f = 0.5), method = m)

      expect_equal(solve4a$intestine, solve5a$intestine)
      expect_equal(solve4a$blood, solve5a$blood)
    })

    test_that(sprintf("F=2 works with parameter-based F (%s)", m), {
      solve5b <- solve(mod5, et, c(f = 2), method = m)

      expect_equal(solve3$intestine, solve5b$intestine)
      expect_equal(solve3$blood, solve5b$blood)
    })
  }
})