tests/testthat/test-io-parquet.R

In duckplyr: A 'DuckDB'-Backed Version of 'dplyr'

test_that("Roundtrip to Parquet works", {
  local_options(lifecycle_verbosity = "quiet")

  df <- tibble(a = 1:3, b = letters[4:6])

  path_parquet <- withr::local_tempfile(fileext = ".parquet")

  df_to_parquet(df, path_parquet)
  out <- df_from_parquet(path_parquet)

  expect_equal(out, df)
})

test_that("Writing to Parquet works without materialization", {
  local_options(lifecycle_verbosity = "quiet")

  n_calls <- 0
  withr::local_options(duckdb.materialize_callback = function(...) {
    n_calls <<- n_calls + 1
  })

  df <- tibble(a = 1:3, b = letters[4:6])
  path_parquet <- withr::local_tempfile(fileext = ".parquet")

  df %>%
    as_duckplyr_df_impl() %>%
    select(b, a) %>%
    df_to_parquet(path_parquet)

  expect_equal(n_calls, 0)

  out <- df_from_parquet(path_parquet)
  expect_equal(n_calls, 0)

  # Side effect
  nrow(out)
  expect_equal(n_calls, 1)

  expect_equal(out, df[2:1])
})