test_that("feature_standardization returns data frame for not cross sectional", {
  set.seed(1)
  df <- feature_standardization(
    df            = generate_test_data(),
    group_by_col  = times,
    excluded_cols = entities
  )
  expect_s3_class(df, "data.frame")
})

test_that("feature_standardization returns tibble for cross-sectional demeaning (time effects)", {
  set.seed(1)
  df <- feature_standardization(
    df            = generate_test_data(),
    group_by_col  = times,
    excluded_cols = entities
  )
  expect_s3_class(df, "tbl")
})

test_that("feature_standardization returns all columns provided", {
  set.seed(1)
  df <- feature_standardization(
    df            = generate_test_data(),
    group_by_col  = times,
    excluded_cols = entities
  )
  expect_equal(length(df), length(generate_test_data()))
  expect_equal(colnames(df), colnames(generate_test_data()))
})

test_that("feature_standardization returns all rows provided", {
  set.seed(1)
  df <- feature_standardization(
    df            = generate_test_data(),
    group_by_col  = times,
    excluded_cols = entities
  )
  expect_equal(nrow(df), nrow(generate_test_data()))
})