From 8b314a3e684c838992c2110072ed04f28793f94e Mon Sep 17 00:00:00 2001
From: eitsupi <ts1s1andn@gmail.com>
Date: Thu, 6 Feb 2025 03:51:32 +0000
Subject: [PATCH] fix: sub-day precision Date should be floored when treated as
 integer

---
 R/write-parquet.R                     |  9 ++++-----
 tests/testthat/test-write-parquet-2.R | 15 +++++++++++++++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/R/write-parquet.R b/R/write-parquet.R
index 9690d46..e456f89 100644
--- a/R/write-parquet.R
+++ b/R/write-parquet.R
@@ -162,10 +162,9 @@ prepare_write_df <- function(x) {
   }
 
   # Date must be integer
-  dates <- which(vapply(x, "inherits", "Date", FUN.VALUE = logical(1)))
-  for (idx in dates) {
-    # this keeps the class
-    mode(x[[idx]]) <- "integer"
+  double_dates <- which(vapply(x, function(x) inherits(x, "Date") && is.double(x), FUN.VALUE = logical(1)))
+  for (idx in double_dates) {
+    x[[idx]] <- .Date(as.integer(floor(as.numeric(x[[idx]]))))
   }
 
   # Convert hms to double
@@ -405,4 +404,4 @@ append_parquet <- function(
   } else {
     res
   }
-}
\ No newline at end of file
+}
diff --git a/tests/testthat/test-write-parquet-2.R b/tests/testthat/test-write-parquet-2.R
index 8b1ec85..d6f8ec9 100644
--- a/tests/testthat/test-write-parquet-2.R
+++ b/tests/testthat/test-write-parquet-2.R
@@ -186,3 +186,18 @@ test_that("zstd compression", {
   expect_equal(read_parquet_page(tmp, 4L)$codec, "ZSTD")
   expect_equal(read_parquet(tmp), d);
 })
+
+test_that("Conversion of sub-dates prior Posix origin is correct", {
+  data <- data.frame(
+    days = as.Date(c(-1.1, -0.1, 0, 0.1, 1.1), origin = "1970-01-01")
+  )
+
+  tmp <- tempfile(fileext = ".parquet")
+  on.exit(unlink(tmp), add = TRUE)
+
+  write_parquet(data, tmp)
+  expect_equal(
+    as.character(as.data.frame(read_parquet(tmp))$date),
+    as.character(data$date)
+  )
+})