describe("nRegression function tests",{

  library(nRegression)

  ## variables
  power = 0.9
  step.age <- "Age ~ N(45, 10)"
  step.female <- "Female ~ binary(0.53)"
  step.health.percentile <- "Health.Percentile ~ U(0,100)"
  step.exercise.sessions <- "Exercise.Sessions ~ Poisson(2)"
  step.diet <- "Diet ~ sample(('Light', 'Moderate', 'Heavy'), (0.2, 0.45, 0.35))"
  step.healthy.lifestyle <- "Healthy.Lifestyle ~ logistic(log(0.45) - 0.1 * (Age -45) + 0.05 * Female + 0.01 * Health.Percentile + 0.5 * Exercise.Sessions - 0.1 * (Diet == 'Moderate') - 0.4 * (Diet == 'Heavy'))"
  step.weight <- "Weight ~ lm(150 - 15 * Female + 0.5 * Age - 0.1 * Health.Percentile - 0.2 * Exercise.Sessions  + 5 * (Diet == 'Moderate') + 15 * (Diet == 'Heavy') - 2 * Healthy.Lifestyle + N(0, 10))"
  the.steps <- c(step.age, step.female, step.health.percentile, step.exercise.sessions, step.diet, step.healthy.lifestyle, step.weight)
  the.variable = "Exercise.Sessions"
  conf.level = 0.95

  seed = 41
  vstr = 3.6
  num.experiments = 5
  n.start = 200
  n.min = 1
  n.max = 400
  increment = 100
  stop.threshold = 1

  #1 Simulations for Logistic Regression

  the.formula.logistic <- Healthy.Lifestyle ~ Age + Female + Health.Percentile + Exercise.Sessions + Weight
  model.type = "logistic"


  n.logistic = nRegression(the.steps = the.steps, num.experiments = num.experiments, the.formula = the.formula.logistic, the.variable = the.variable, seed = seed, n.start = n.start, n.min = n.min, n.max = n.max, increment = increment, stop.threshold = stop.threshold, power = power, model.type = model.type, verbose = T)

  test_that("nRegression (Logistic Regression) returns a list of length 4", {
    expect_length(n.logistic, 4)
  })

  test_that("nRegression (Logistic Regression) returns expected names", {
    expect_named(n.logistic, c("n", "power", "iterations", "simstudy"))
  })

  test_that("nRegression (Logistic Regression) returns expected n value", {
    expect_equal(n.logistic$n, 101)
  })

  test_that("nRegression (Logistic Regression) returns expected power value", {
    expect_equal(n.logistic$power, 1)
  })


  test_that("nRegression (Logistic Regression) returns expected simstudy names", {
    expect_named(n.logistic$simstudy, c("the.steps", "simdat", "statistics", "sim.analysis"))
  })

  test_that("nRegression (Logistic Regression) returns expected iterations", {
    expected_iterations <- data.frame(
      i = c(1, 2, 3, 4, 5, 6, 7, 8),
      lower = c(1, 1, 1, 51, 76, 89, 95, 98),
      n = c(200, 101, 51, 76, 89, 95, 98, 100),
      upper = c(400, 200, 101, 101, 101, 101, 101, 101),
      power = c(1.000, 1.000, 0.600, 0.800, 0.600, 0.800, 0.800, 0.800)
    )

    expect_equal(as.data.frame(n.logistic$iterations), expected_iterations)
  })

  #2 Simulations for Linear Regression

  ## Variables

  the.formula.lm <- Weight ~ Age + Female + Health.Percentile + Exercise.Sessions + Healthy.Lifestyle
  model.type = "lm"
  num.experiments <- 5

  n.start = 500
  n.max <- 600
  increment = 50
  stop.threshold = 10

  the.variable = "Healthy.LifestyleTRUE"

  n.lm = nRegression(the.steps = the.steps, num.experiments = num.experiments, the.formula = the.formula.lm, the.variable = the.variable, seed = seed, n.start = n.start, n.max = n.max, increment = increment, stop.threshold = stop.threshold, power = power, model.type = model.type, verbose = T)


  test_that("nRegression (Linear Regression) returns a list of length 4", {
    expect_length(n.lm, 4)
  })

  test_that("nRegression (Linear Regression) returns expected names", {
    expect_named(n.lm, c("n", "power", "iterations", "simstudy"))
  })

  test_that("nRegression (Linear Regression) returns expected n value", {
    expect_equal(n.lm$n, 594)
  })

  test_that("nRegression (Linear Regression) returns expected power value", {
    expect_equal(n.lm$power, 1)
  })


  test_that("nRegression (Linear Regression) returns expected simstudy names", {
    expect_named(n.lm$simstudy, c("the.steps", "simdat", "statistics", "sim.analysis"))
  })

  test_that("nRegression (Linear Regression) returns expected iterations", {
    expected_iterations <- data.frame(
      i = c(1, 2, 3, 4, 5, 6),
      lower = c(1, 500, 550, 575, 588, 588),
      n = c(500, 550, 575, 588, 594, 591),
      upper = c(600, 600 , 600, 600, 600, 594),
      power = c(0.6, 0.4, 0.8, 0.8, 1.0, 0.8)
    )

    expect_equal(as.data.frame(n.lm$iterations), expected_iterations)
  })


})