require(xgboost)

context("monotone constraints")

set.seed(1024)
x = rnorm(1000, 10)
y = -1*x + rnorm(1000, 0.001) + 3*sin(x)
train = matrix(x, ncol = 1)


test_that("monotone constraints for regression", {
  bst = xgboost(data = train, label = y, max_depth = 2,
                eta = 0.1, nthread = 2, nrounds = 100, verbose = 0,
                monotone_constraints = -1)
  
  pred = predict(bst, train)
  
  ind = order(train[,1])
  pred.ord = pred[ind]
  expect_true({
    !any(diff(pred.ord) > 0)
  }, "Monotone Contraint Satisfied")
  
})