dag returns a tibble

ref #415

NEWS.md

@@ -1,6 +1,12 @@
 Upcoming Release
 ==========================================================
 
+### Possibly Breaking Changes
+
+* `redcap_read()`, `redcap_read_oneshot()`, `redcap_dag_read()`, `redcap_log_read()` and `redcap_report()` return a tibble instead of a data.frame.  (#415)
+
+    This should affect client code only if you expect a call like `ds[, 3]` to return a vector instead of a single-column data.frame/tibble.  One solution is to upcast the tibble to a data.frame (with something like `as.data.frame()`).  We recommend using an approach that works for both data.frames and tibbles, such as `ds[[3]]` or `dplyr::pull(ds, "gender")`.
+
 ### New Features
 
 * New `redcap_log_read()` function.  Exports a project's log.  (Thanks @joundso, #383, #320)

R/redcap-dag-read.R

@@ -93,8 +93,7 @@ redcap_dag_read <- function(
           file            = I(kernel$raw_text),
           locale          = locale,
           show_col_types  = FALSE
-        ) %>%
-        as.data.frame(),
+        ),
 
       # Don't print the warning in the try block.  Print it below,
       #   where it's under the control of the caller.

tests/testthat/test-dag-read.R

@@ -17,9 +17,14 @@ test_that("smoke", {
 test_that("dag-default", {
   testthat::skip_on_cran()
   expected_data <-
-    structure(list(data_access_group_name = c("dag_1", "dag_2"),
+    structure(
+      list(data_access_group_name = c("dag_1", "dag_2"),
       unique_group_name = c("dag_1", "dag_2")), row.names = c(NA,
-      -2L), class = "data.frame"
+      -2L), spec = structure(list(cols = list(data_access_group_name = structure(list(), class = c("collector_character",
+      "collector")), unique_group_name = structure(list(), class = c("collector_character",
+      "collector"))), default = structure(list(), class = c("collector_guess",
+      "collector")), delim = ","), class = "col_spec"), class = c("spec_tbl_df",
+      "tbl_df", "tbl", "data.frame")
     )
   expect_message(
     actual <- redcap_dag_read(
@@ -36,9 +41,13 @@ test_that("dag-default", {
 test_that("dag-default", {
   testthat::skip_on_cran()
   expected_data <-
-    structure(list(data_access_group_name = character(0),
-      unique_group_name = character(0)), row.names = integer(0),
-      class = "data.frame"
+    structure(
+      list(data_access_group_name = character(0), unique_group_name = character(0)), row.names = integer(0), spec = structure(list(
+      cols = list(data_access_group_name = structure(list(), class = c("collector_character",
+      "collector")), unique_group_name = structure(list(), class = c("collector_character",
+      "collector"))), default = structure(list(), class = c("collector_guess",
+      "collector")), delim = ","), class = "col_spec"), class = c("spec_tbl_df",
+      "tbl_df", "tbl", "data.frame")
     )
 
   expect_message(