test_that("check if function delP() works as expected", {
  # beta is a vector of zeros
  beta <- double(15)
  gr <- rep(1:5, each = 3)
  list1 <- list()
  for (i in seq(5)) {
    list1[[i]] <- matrix(rep(NaN, 9), nrow = 3)
  }
  expect_equal(delP(beta, gr), Matrix::bdiag(list1))

  # beta is a matrix of zeros
  beta <- matrix(double(15))
  expect_equal(delP(beta, gr), Matrix::bdiag(list1))

  # beta length is not equal to gr length
  gr <- rep(1:5, 2)
  expect_warning(delP(beta, gr))
})

test_that("check if function exact_df() works as expected", {
  set.seed(1)
  n <- 100
  beta <- c(5, 5, 5, -5, -5, -5, 1, 0, 1, 0, 0, 0, 0, 2, 0)
  gr <- rep(1:5, each = 3)
  X <- matrix(rnorm(n * length(beta)), n)
  y <- X %*% beta + rnorm(n)
  out <- sparsegl(X, y, gr)

  # check the length of the exact DOF
  expect_equal(length(exact_df(out, X)), 100)

  # check if exact_df produce 0 when all betas are zero at some lambda
  for (i in seq(100)) {
    if (sum(abs(out$beta[, i])) == 0) {
      expect_equal(exact_df(out, X)[i], 0)
    }
  }
})

test_that("risk estimation functions reasonably", {
  set.seed(1)
  n <- 100
  beta <- c(5, 5, 5, -5, -5, -5, 1, 0, 1, 0, 0, 0, 0, 2, 0)
  gr <- rep(1:5, each = 3)
  X <- matrix(rnorm(n * length(beta)), n)
  y <- X %*% beta + rnorm(n)
  out <- sparsegl(X, y, gr)
  out_logit <- sparsegl(X, rbinom(n, 1, .5), gr, family = "binomial")

  expect_error(estimate_risk(out_logit, X))
  expect_error(estimate_risk(out, approx_df = FALSE))
  expect_named(
    estimate_risk(out, approx_df = TRUE),
    c("lambda", "df", "AIC", "BIC", "GCV")
  )
  expect_named(
    estimate_risk(out, type = c("BIC", "GCV"), approx_df = TRUE),
    c("lambda", "df", "BIC", "GCV")
  )
  expect_identical(
    estimate_risk(out, approx_df = TRUE),
    estimate_risk(out, X, approx_df = TRUE)
  )
  X[abs(X) < 1] <- 0
  X <- as_dgCMatrix(X)
  out_sparse <- sparsegl(X, y, gr)
  expect_named(
    estimate_risk(out_sparse, approx_df = TRUE),
    c("lambda", "df", "AIC", "BIC", "GCV")
  )
  expect_named(
    estimate_risk(out_sparse, X),
    c("lambda", "df", "AIC", "BIC", "GCV")
  )
  out_lam <- sparsegl(X, y, gr, lambda = c(100, 10, 1, .1, .01))
  er <- estimate_risk(out_lam, X)
  expect_named(er, c("lambda", "df", "AIC", "BIC", "GCV"))
  expect_length(er$lambda, 5L)
})