From 5b74ba09dc48c734ffeb4414a95a53a046fa45f5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?G=C3=A1bor=20Cs=C3=A1rdi?= <csardi.gabor@gmail.com>
Date: Mon, 17 Feb 2025 10:49:36 +0100
Subject: [PATCH] Test write_parquet() temporal types w/ Python polars

---
 .github/workflows/R-CMD-check.yaml   |  4 +--
 .github/workflows/test-coverage.yaml |  4 +--
 tests/testthat/helper.R              | 19 ++++++++++++
 tests/testthat/test-pypolars.R       | 46 ++++++++++++++++++++++++++++
 4 files changed, 69 insertions(+), 4 deletions(-)
 create mode 100644 tests/testthat/test-pypolars.R

diff --git a/.github/workflows/R-CMD-check.yaml b/.github/workflows/R-CMD-check.yaml
index 0839064..1a19309 100644
--- a/.github/workflows/R-CMD-check.yaml
+++ b/.github/workflows/R-CMD-check.yaml
@@ -58,9 +58,9 @@ jobs:
             "~/.pip/pip.conf"
           )
           if (Sys.which("pip3") != "") {
-            system("pip3 install pyarrow pandas")
+            system("pip3 install pyarrow pandas polars")
           } else {
-            system("pip install pyarrow pandas")
+            system("pip install pyarrow pandas polars")
           }
         shell: Rscript {0}
 
diff --git a/.github/workflows/test-coverage.yaml b/.github/workflows/test-coverage.yaml
index 76e2b62..33141a1 100644
--- a/.github/workflows/test-coverage.yaml
+++ b/.github/workflows/test-coverage.yaml
@@ -32,9 +32,9 @@ jobs:
             "~/.pip/pip.conf"
           )
           if (Sys.which("pip3") != "") {
-            system("pip3 install pyarrow pandas")
+            system("pip3 install pyarrow pandas polars")
           } else {
-            system("pip install pyarrow pandas")
+            system("pip install pyarrow pandas polars")
           }
         shell: Rscript {0}
 
diff --git a/tests/testthat/helper.R b/tests/testthat/helper.R
index 50eff89..7afb624 100644
--- a/tests/testthat/helper.R
+++ b/tests/testthat/helper.R
@@ -18,6 +18,25 @@ skip_without_pyarrow <- function() {
   }
 }
 
+skip_without_polars <- function() {
+  skip_on_cran()
+  if (tolower(Sys.getenv("_R_CHECK_FORCE_SUGGESTS_")) != "false") return()
+  pyscript <- r"[
+    import polars
+  ]"
+  pytmp <- tempfile(fileext = ".py")
+  on.exit(unlink(pytmp), add = TRUE)
+  writeLines(pyscript, pytmp)
+  py <- if (Sys.which("python3") != "") "python3" else "python"
+  res <- tryCatch(
+    processx::run(py, pytmp, stderr = "2>&1"),
+    error = function(err) err
+  )
+  if (inherits(res, "error")) {
+    skip("missing polars in Python")
+  }
+}
+
 skip_without <- function(pkgs) {
   if (any(c("arrow", "duckdb") %in% pkgs)) skip_on_cran()
   if (tolower(Sys.getenv("_R_CHECK_FORCE_SUGGESTS_")) != "false") return()
diff --git a/tests/testthat/test-pypolars.R b/tests/testthat/test-pypolars.R
new file mode 100644
index 0000000..ada9947
--- /dev/null
+++ b/tests/testthat/test-pypolars.R
@@ -0,0 +1,46 @@
+test_that("polars can read temporal types", {
+  skip_without_polars()
+
+  tmp <- tempfile(fileext = ".parquet")
+  on.exit(unlink(tmp), add = TRUE)
+
+  do <- function(df, path = tmp) {
+    write_parquet(df, path)
+    pyscript <- sprintf(r"[
+import polars as pl
+pl.read_parquet("%s")
+    ]", normalizePath(path, winslash = "/"))
+    pytmp <- tempfile(fileext = ".py")
+    on.exit(unlink(pytmp), add = TRUE)
+    writeLines(pyscript, pytmp)
+    py <- if (Sys.which("python3") != "") "python3" else "python"
+    processx::run(py, pytmp, stderr = "2>&1")
+  }
+
+  # Date
+  df_date <- data.frame(x = Sys.Date())
+  expect_silent(do(df_date))
+
+  # hms, integer
+  # it is unclear if this ever comes up in practice
+  df_hmsi <- data.frame(
+    x = structure(0L, units = "secs", class = c("hms", "difftime"))
+  )
+  expect_silent(do(df_hmsi))
+
+  # hms, double
+  df_hmsd <- data.frame(x = hms::hms(0))
+  expect_silent(do(df_hmsd))
+
+  # difftime
+  df_difftime <- data.frame(x = as.difftime(1, units = "secs"))
+  expect_silent(do(df_difftime))
+
+  # POSIXct
+  df_posixct <- data.frame(x = Sys.time())
+  expect_silent(do(df_posixct))
+
+  # factor
+  df_factor <- data.frame(x = as.factor(c("a", "a")))
+  expect_silent(do(df_factor))
+})