nealrichardson commented on code in PR #14160:
URL: https://github.com/apache/arrow/pull/14160#discussion_r975171976
##########
r/tests/testthat/test-dplyr-collect.R:
##########
@@ -276,3 +276,16 @@ test_that("collapse doesn't unnecessarily add
ProjectNodes", {
)
expect_length(grep("ProjectNode", plan), 1)
})
+
+test_that("compute", {
Review Comment:
I would put this test in `test-dplyr-query.R` and rename this file back to
`test-dplyr-collapse.R` since it's all about `collapse()`. I get the point of
trying to have the R and test file names matching, but it's not so
straightforward here--nearly every dplyr test we have calls `collect()` so
we're testing it everywhere.
Also let's give the test a more expressive name
```suggestion
test_that("compute() on a grouped query returns a Table with groups in
metadata", {
```
##########
r/tests/testthat/test-dplyr-query.R:
##########
@@ -119,7 +119,7 @@ test_that("collect(as_data_frame=FALSE)", {
filter(int > 5) %>%
group_by(int) %>%
collect(as_data_frame = FALSE)
- expect_s3_class(b4, "arrow_dplyr_query")
Review Comment:
I think we need a test (and matching code change) that a Table with groups
in the `$metadata` prints that it is grouped. Currently, the print method does
not reveal that you have groupings, even though they get restored when you
`as.data.frame()`:
```
> tab <- arrow_table(mtcars)
> tab$metadata$r$attributes$.group_vars <- "cyl"
> tab
Table
32 rows x 11 columns
$mpg <double>
$cyl <double>
$disp <double>
$hp <double>
$drat <double>
$wt <double>
$qsec <double>
$vs <double>
$am <double>
$gear <double>
$carb <double>
See $metadata for additional Schema metadata
```
I wonder what else is lost or concealed by this change. This feature of
reading groups from `$metadata$r$attributes$.group_vars` was a bit of a hack
and not something we're generally relying on, so I don't think it's a simple
change. Or at least, it's not something we can just rely that the test suite
already covers everything we care about. (Search for ".group_vars" in the code,
it's not touched in many places, and only in one test.)
Not a reason not to do it, just need to be thorough.
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