test_that("nlmm function validates package and inputs", {
  
  skip_if_not_installed("nlme")
  
  dat <- data.frame(
    id = factor(rep(1:5, each = 4)),
    x = rep(1:4, 5),
    y = rnorm(20)
  )
  
  expect_error(
    fit_nlmm(
      y ~ x,
      data = dat
    ),
    regexp = "nonlinear|random|start",
    ignore.case = TRUE
  )
})

test_that("nlmm validates model", {
  
  skip_if_not_installed("nlme")
  
  dat <- data.frame(
    id = factor(rep(1:5, each = 4)),
    x = rep(0:3, 5),
    y = rnorm(20)
  )
  
  expect_error(
    fit_nlmm(
      model = "y ~ x",
      data = dat,
      fixed = x ~ 1,
      random = x ~ 1 | id
    ),
    "'model' must be a formula"
  )
})


test_that("nlmm validates data", {
  
  skip_if_not_installed("nlme")
  
  expect_error(
    fit_nlmm(
      model = y ~ x,
      data = list(y = 1:5, x = 1:5),
      fixed = x ~ 1,
      random = x ~ 1 | id
    ),
    "'data' must be a data frame"
  )
})


test_that("nlmm requires fixed effects", {
  
  skip_if_not_installed("nlme")
  
  dat <- data.frame(
    id = factor(rep(1:5, each = 4)),
    x = rep(0:3, 5),
    y = rnorm(20)
  )
  
  expect_error(
    fit_nlmm(
      model = y ~ SSasymp(x, Asym, R0, lrc),
      data = dat,
      random = Asym ~ 1 | id
    ),
    "'fixed' must be supplied"
  )
})


test_that("nlmm requires random effects", {
  
  skip_if_not_installed("nlme")
  
  dat <- data.frame(
    id = factor(rep(1:5, each = 4)),
    x = rep(0:3, 5),
    y = rnorm(20)
  )
  
  expect_error(
    fit_nlmm(
      model = y ~ SSasymp(x, Asym, R0, lrc),
      data = dat,
      fixed = Asym + R0 + lrc ~ 1
    ),
    "'random' must be supplied"
  )
})


test_that("nlmm validates estimation method", {
  
  skip_if_not_installed("nlme")
  
  dat <- data.frame(
    id = factor(rep(1:5, each = 4)),
    x = rep(0:3, 5),
    y = rnorm(20)
  )
  
  expect_error(
    fit_nlmm(
      model = y ~ x,
      data = dat,
      fixed = x ~ 1,
      random = x ~ 1 | id,
      method = "INVALID"
    ),
    "should be one of"
  )
})

test_that("fit_nlmm validates model formula", {
  
  skip_if_not_installed("nlme")
  
  dat <- data.frame(
    y = rnorm(10),
    x = rnorm(10),
    id = factor(rep(1:5, each = 2))
  )
  
  expect_error(
    fit_nlmm(
      model = "y ~ x",
      data = dat,
      fixed = x ~ 1,
      random = x ~ 1 | id
    ),
    "'model' must be a formula"
  )
})

test_that("fit_nlmm validates data", {
  
  skip_if_not_installed("nlme")
  
  expect_error(
    fit_nlmm(
      model = y ~ x,
      data = list(y = 1:5, x = 1:5),
      fixed = x ~ 1,
      random = x ~ 1
    ),
    "'data' must be a data frame"
  )
})

test_that("fit_nlmm requires random effects", {
  
  skip_if_not_installed("nlme")
  
  dat <- data.frame(
    y = rnorm(10),
    x = rnorm(10)
  )
  
  expect_error(
    fit_nlmm(
      model = y ~ x,
      data = dat,
      fixed = x ~ 1
    ),
    "'random' must be supplied"
  )
})

test_that("fit_nlmm rejects invalid method", {
  
  skip_if_not_installed("nlme")
  
  dat <- data.frame(
    y = rnorm(10),
    x = rnorm(10),
    id = factor(rep(1:5, each = 2))
  )
  
  expect_error(
    fit_nlmm(
      model = y ~ x,
      data = dat,
      fixed = x ~ 1,
      random = x ~ 1 | id,
      method = "INVALID"
    )
  )
})