diff --git a/DESCRIPTION b/DESCRIPTION
index 536f03c..5461ecc 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -11,15 +11,17 @@ Description: Assist with management of clinical trial data in the SDTM and ADaM
   and verification of SDTM data.
 Depends: R (>= 3.5)
 Imports:
- dplyr,
- ggplot2,
- labeling,
- lubridate,
- methods,
- readr,
- rio,
- rlang,
- tidyr
+    dplyr,
+    ggplot2,
+    labeling,
+    lifecycle,
+    lubridate,
+    metatools,
+    methods,
+    readr,
+    rio,
+    rlang,
+    tidyr
 Suggests:
     covr,
     scales,
diff --git a/NAMESPACE b/NAMESPACE
index d79ca56..09ff9cb 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -1,6 +1,14 @@
 # Generated by roxygen2: do not edit by hand
 
 S3method(c_to_n,character)
+S3method(c_to_n,data.frame)
+S3method(c_to_n,factor)
+S3method(c_to_n,integer)
+S3method(c_to_n,logical)
+S3method(c_to_n,numeric)
+S3method(sdtm_dtc_to_datetime,Date)
+S3method(sdtm_dtc_to_datetime,POSIXt)
+S3method(sdtm_dtc_to_datetime,character)
 S3method(sdtm_dtc_to_datetime,data.frame)
 S3method(sdtm_dtc_to_datetime,list)
 S3method(sdtm_first_dose,data.frame)
@@ -42,22 +50,14 @@ export(sdtm_first_dose)
 export(sdtm_time_actual)
 export(simplify_sdtm_names)
 export(standardize_sdtm_id)
-export(strip_attributes)
-export(supp_reformat)
-importFrom(dplyr,anti_join)
 importFrom(dplyr,case_when)
 importFrom(dplyr,group_by_at)
 importFrom(dplyr,is_grouped_df)
-importFrom(dplyr,recode)
 importFrom(dplyr,rename_all)
 importFrom(dplyr,rename_at)
 importFrom(dplyr,summarize_at)
 importFrom(lubridate,format_ISO8601)
 importFrom(lubridate,is.POSIXt)
 importFrom(lubridate,ymd_hms)
-importFrom(readr,type_convert)
 importFrom(rio,import)
-importFrom(rlang,abort)
-importFrom(rlang,inform)
-importFrom(tidyr,spread)
 importFrom(tools,file_path_sans_ext)
diff --git a/NEWS.md b/NEWS.md
new file mode 100644
index 0000000..fd164db
--- /dev/null
+++ b/NEWS.md
@@ -0,0 +1,4 @@
+# Rsdtm 0.0.9017
+
+* Added `auto_supp` and `auto_dtc` arguments to `import_sdtm()`
+* Removed `merge_supp()` and related functions in favor of `metatools::combine_supp()`
diff --git a/R/c_to_n.R b/R/c_to_n.R
index 5f1afb7..258cb12 100644
--- a/R/c_to_n.R
+++ b/R/c_to_n.R
@@ -57,23 +57,27 @@ c_to_n.character <- function(x, ...,
 }
 
 #' @describeIn c_to_n For factors.
+#' @export
 c_to_n.factor <- function(x, ...) {
   c_to_n.character(as.character(x), ...)
 }
 
 #' @describeIn c_to_n For numeric vectors.
+#' @export
 c_to_n.numeric <- function(x, ...) {
   warning("`c_to_n` is generally not called on a numeric vector.  Please verify code.")
   x
 }
 
 #' @describeIn c_to_n For integer vectors.
+#' @export
 c_to_n.integer <- function(x, ...) {
   warning("`c_to_n` is generally not called on an integer vector.  Please verify code.")
   x
 }
 
 #' @describeIn c_to_n For logical vectors (only handles all-NA case).
+#' @export
 c_to_n.logical <- function(x, ...) {
   if (!all(is.na(x))) {
     warning("`c_to_n` does not set non-NA logical values to numeric.")
@@ -84,6 +88,7 @@ c_to_n.logical <- function(x, ...) {
 #' @describeIn c_to_n For data.frames and similar, finds columns matching the
 #'   regular expression pattern `"^..(ST|OR).*C$"`.  data.frame method does not
 #'   replace numeric columns that already exist.
+#' @export
 c_to_n.data.frame <- function(x, ..., verbose=TRUE) {
   columns_named_c <- grep(pattern="^..(ST|OR).*C$", x=names(x), value=TRUE)
   columns_named_n <- grep(pattern="^..(ST|OR).*N$", x=names(x), value=TRUE)
diff --git a/R/date_conversion.R b/R/date_conversion.R
index 7ad2133..3f9c6af 100644
--- a/R/date_conversion.R
+++ b/R/date_conversion.R
@@ -3,8 +3,11 @@
 #'
 #' @param x The data to convert
 #' @param date_col_pattern A regex to search column names for dates to convert.
-#' @param truncated Passed to \code{lubridate::ymd_hms}
-#' @param ... Additional arguments passed to \code{lubridate::ymd_hms}
+#' @param truncated Passed to `lubridate::ymd_hms()` or `lubridate::ymd()`; the
+#'   `truncated` argument is always considered relative to `ymd_hms` formatting,
+#'   so it is used as `truncated - 3` for dates.
+#' @param ... Additional arguments passed to `lubridate::ymd_hms()` or
+#'   `lubridate::ymd()`
 #' @return The data with the date converted.  Note that all dates will be
 #'   returned as POSIXct objects, so partial dates will appear as the
 #' @family Date management and conversion
@@ -16,21 +19,51 @@ sdtm_dtc_to_datetime <- function(x, ...) {
 #' @rdname sdtm_dtc_to_datetime
 #' @export
 sdtm_dtc_to_datetime.list <- function(x, ...) {
-  lapply(X=x,
-         FUN=sdtm_dtc_to_datetime,
-         ...)
+  lapply(X=x, FUN=sdtm_dtc_to_datetime, ...)
 }
 
 #' @rdname sdtm_dtc_to_datetime
 #' @export
-sdtm_dtc_to_datetime.data.frame <- function(x, date_col_pattern="DTC$", truncated=5, ...) {
+sdtm_dtc_to_datetime.Date <- function(x, ...) {
+  x
+}
+
+#' @rdname sdtm_dtc_to_datetime
+#' @export
+sdtm_dtc_to_datetime.POSIXt <- function(x, ...) {
+  x
+}
+
+#' @rdname sdtm_dtc_to_datetime
+#' @export
+sdtm_dtc_to_datetime.character <- function(x, truncated=5, ...) {
+  # Treat empty strings as NA
+  x_current <- x
+  x_current[x_current %in% ""] <- NA_character_
+
+  # Detect columns that only contain dates and load them as dates rather than
+  # datetimes
+  is_date <-
+    grepl(
+      x = x_current,
+      pattern = paste0("^", pattern_ISO8601_calendar_date(), "$")
+    )
+  if (all(is.na(x_current) | is_date)) {
+    # If it is a date
+    x <- lubridate::ymd(x_current, truncated=max(truncated - 3, 0), ...)
+  } else {
+    # Otherwise try to consider it a datetime
+    x <- lubridate::ymd_hms(x_current, truncated=truncated, ...)
+  }
+  x
+}
+
+#' @rdname sdtm_dtc_to_datetime
+#' @export
+sdtm_dtc_to_datetime.data.frame <- function(x, date_col_pattern="DTC$", ...) {
   date_col_names <- grep(names(x), pattern=date_col_pattern, value=TRUE)
   for (current_name in date_col_names) {
-    if (!lubridate::is.POSIXt(x[[current_name]])) {
-      x[[current_name]] <- ymd_hms(x[[current_name]], truncated=truncated, ...)
-    } else {
-      message("Column ", current_name, " is already a datetime object.")
-    }
+    x[[current_name]] <- sdtm_dtc_to_datetime(x[[current_name]])
   }
   x
 }
diff --git a/R/import_sdtm.R b/R/import_sdtm.R
index 901d4aa..b93a284 100644
--- a/R/import_sdtm.R
+++ b/R/import_sdtm.R
@@ -6,6 +6,9 @@
 #'   first extension in \code{extension_choice} with a usable file will be used,
 #'   and a warning will be given for subsequent files.
 #' @param ignore_case Passed to \code{list.files} when loading a directory.
+#' @param auto_supp Automatically combine --SUPP data with the main SDTM domain
+#'   and remove the --SUPP data from the returned list of data.frames.
+#' @param auto_dtc Automatically convert --DTC columns to date/times?
 #' @param return_type When loading a single file, what type of output should be
 #'   provided?
 #' @param ... Arguments passed to \code{rio::import}
@@ -22,6 +25,8 @@
 import_sdtm <- function(path,
                         extension_choice = c(".sas7bdat", ".xpt"),
                         ignore_case = TRUE,
+                        auto_supp = FALSE,
+                        auto_dtc = FALSE,
                         ...) {
   stopifnot(
     is.character(path),
@@ -54,6 +59,22 @@ import_sdtm <- function(path,
     )
     ret <- append_no_duplicate_names(ret, tmp_ret, method=stop)
   }
+
+  if (auto_supp) {
+    supp_domains <- names(ret)[startsWith(names(ret), "SUPP")]
+    for (current_supp in supp_domains) {
+      current_domain <- gsub(x = current_supp, pattern = "^SUPP", replacement = "")
+      if (!(current_domain %in% names(ret))) {
+        stop("Domain ", current_domain, " was not found when trying to auto-combine --SUPP data with ", current_supp)
+      }
+      ret[[current_domain]] <- metatools::combine_supp(ret[[current_domain]], supp = ret[[current_supp]])
+      ret[[current_supp]] <- NULL
+    }
+  }
+
+  if (auto_dtc) {
+    ret <- sdtm_dtc_to_datetime(ret, ...)
+  }
   ret
 }
 
diff --git a/R/merge_supp.R b/R/merge_supp.R
index a2b27d1..e59b402 100644
--- a/R/merge_supp.R
+++ b/R/merge_supp.R
@@ -1,192 +1,9 @@
 #' Merge a supplementary dataset into a primary dataset
 #'
-#' @param primary the data.frame of the primary dataset
-#' @param supplementary the data.frame of the supplementary dataset
-#' @param remove_attributes If \code{TRUE}, remove all attributes from all
-#'   columns (this will break many classes); if \code{FALSE}, remove no
-#'   attributes from any columns; if a character, remove those attributes from
-#'   the columns.
-#' @inheritParams supp_reformat
-#' @return \code{primary} merged with \code{supplementary} where new column
-#'   names come from the \code{QNAM} column in \code{supplementary}
-#' @seealso \code{\link{supp_reformat}}
-#' @export
-#' @importFrom dplyr anti_join
-#' @importFrom rlang abort inform
-merge_supp <- function(primary, supplementary, remove_attributes = c("label"), auto_convert=FALSE) {
-  if (length(unique(supplementary$RDOMAIN)) != 1) {
-    stop("Only direct relationships with supplementary domains are currently supported.")
-  }
-  if (is.logical(remove_attributes) && remove_attributes) {
-    primary <- strip_attributes(primary, specific = NULL)
-    supplementary <- strip_attributes(supplementary, specific = NULL)
-  } else if (is.character(remove_attributes)) {
-    primary <- strip_attributes(primary, specific = remove_attributes)
-    supplementary <- strip_attributes(supplementary, specific = remove_attributes)
-  }
-  ret <- primary
-  supp_prep <- supp_reformat(supplementary, auto_convert=auto_convert)
-  for (current_supp_idx in seq_along(supp_prep)) {
-    current_supp <- supp_prep[[current_supp_idx]]
-    current_idvar <- names(supp_prep)[current_supp_idx]
-    if (current_idvar != "") {
-      # Check for a class mismatch between the original and the supp domain idvar
-      if (any(class(current_supp[[current_idvar]]) != class(ret[[current_idvar]]))) {
-        orig <- current_supp[[current_idvar]]
-        current_supp[[current_idvar]] <-
-          methods::as(current_supp[[current_idvar]], Class=class(ret[[current_idvar]]))
-        if (!all(is.na(orig) == is.na(current_supp[[current_idvar]]))) {
-          # Introduction of an NA is a problem
-          rlang::abort(
-            message=sprintf("NA introduced by coercion for supplemental merge in column %s", current_idvar),
-            class="Rsdtm_merge_supp_na_idvar"
-          )
-        } else {
-          rlang::inform(
-            message=
-              sprintf(
-                "Supplemental merge column %s type converted to class: %s",
-                current_idvar,
-                class(ret[[current_idvar]])[1]
-              ),
-            class="Rsdtm_merge_supp_convert_idvar"
-          )
-        }
-      }
-    }
-    current_join_vars <- setdiff(c("STUDYID", "DOMAIN", "USUBJID", current_idvar), "")
-    missed_rows <- dplyr::anti_join(current_supp, ret, by = current_join_vars)
-    if (nrow(missed_rows)) {
-      stop(
-        nrow(missed_rows),
-        " rows from the ",
-        current_idvar,
-        " IDVAR in the SUPP domain do not match rows in the primary ",
-        primary$DOMAIN[1],
-        " dataset."
-      )
-    }
-    ret <- dplyr::left_join(ret, current_supp, by = current_join_vars)
-  }
-  ret
-}
-
-#' Reformat a --SUPP SDTM domain into a list of data.frames ready for merging
-#' into the primary domain.
-#'
-#' @param x a --SUPP SDTM domain object
-#' @param auto_convert should the data be automatically converted using
-#'   `type_convert()`?
-#' @return A list with length the same as \code{unique(x$IDVAR)} with
-#'   data.frames ready for merging into the primary dataset.
-#' @seealso \code{\link{merge_supp}}
-#' @export
-supp_reformat <- function(x, auto_convert=FALSE) {
-  ret <- list()
-  for (current_idvar in unique(x$IDVAR)) {
-    ret <- append(
-      ret,
-      list(
-        supp_reformat_single(
-          x[x$IDVAR %in% current_idvar, ],
-          auto_convert=auto_convert
-        )
-      )
-    )
-  }
-  names(ret) <- unique(x$IDVAR)
-  ret
-}
-
-#' @importFrom dplyr rename_at recode
-#' @importFrom tidyr spread
-#' @importFrom readr type_convert
-supp_reformat_single <- function(x, auto_convert=FALSE) {
-  idvar <- unique(x$IDVAR)
-  if (length(unique(x$RDOMAIN)) != 1) {
-    stop("RDOMAIN column in x must have a single value.")
-  } else if (length(idvar) != 1) {
-    stop("IDVAR column in x must have a single value.")
-  } else if (any(c("APID", "POOLID") %in% names(x))) {
-    stop("APID and POOLID are not yet supported.")
-  }
-  # Columns to drop
-  if (all(x$IDVAR %in% "" & x$IDVARVAL %in% "")) {
-    message(
-      "No IDVAR or IDVARVAL in SUPP", unique(x$RDOMAIN),
-      " data; assuming USUBJID is sufficient for merge."
-    )
-    ret <- x[, setdiff(names(x), c("IDVAR", "IDVARVAL", "QLABEL", "QORIG", "QEVAL")), drop=FALSE]
-    ret <-
-      rename_at(
-        .tbl=ret,
-        .vars="RDOMAIN",
-        .funs=dplyr::recode,
-        RDOMAIN="DOMAIN"
-      )
-  } else {
-    if (any(x$IDVAR %in% "")) {
-      stop("Some IDVAR values are missing (when some IDVAR or IDVARVAL are present) in SUPP", unique(x$RDOMAIN))
-    } else if (any(x$IDVARVAL %in% "")) {
-      stop("Some IDVARVAL values are missing (when some IDVAR or IDVARVAL are present) in SUPP", unique(x$RDOMAIN))
-    }
-    ret <- x[, setdiff(names(x), c("IDVAR", "QLABEL", "QORIG", "QEVAL")), drop=FALSE]
-    ret <-
-      rename_at(
-        .tbl=ret,
-        .vars=c("RDOMAIN", "IDVARVAL"),
-        .funs=recode,
-        RDOMAIN="DOMAIN",
-        IDVARVAL=idvar
-      )
-  }
-  ret <-
-    tidyr::spread(
-      ret,
-      key="QNAM",
-      value="QVAL"
-    )
-  if (auto_convert) {
-    ret <- type_convert(df=ret)
-  }
-  ret
-}
-
-#' Remove attributes from an object
+#' This function is defunct. Use `metatools::combine_supp()` instead.
 #'
-#' @param x The object to remove attributes from
-#' @param specific If \code{NULL}, all attributes are removed.  If a character
-#'   vector, only the named attributes are removed.
-#' @param columns_only Do not strip attributes from the data.frame; only strip
-#'   them from the columns of the data.frame.
-#' @param ... Passed to other `strip_attributes()` methods.
-#' @return \code{x} with fewer attributes.
+#' @param ... Ignored
 #' @export
-strip_attributes <- function(x, specific=NULL, ...) {
-  UseMethod("strip_attributes")
-}
-
-#' @rdname strip_attributes
-strip_attributes.data.frame <- function(x, specific=NULL, columns_only=TRUE, ...) {
-  if (columns_only) {
-    for (nm in seq_along(x)) {
-      x[[nm]] <- strip_attributes(x[[nm]], specific=specific, columns_only=columns_only, ...)
-    }
-    x
-  } else {
-    strip_attributes.default(x, specific=specific, ...)
-  }
-}
-
-#' @rdname strip_attributes
-strip_attributes.default <- function(x, specific=NULL, ...) {
-  if (is.null(specific)) {
-    attributes(x) <- NULL
-    x
-  } else {
-    for (current in specific) {
-      attr(x, current) <- NULL
-    }
-    x
-  }
+merge_supp <- function(...) {
+  lifecycle::deprecate_stop(when = "0.0.9000", what = "merge_supp()", with = "metatools::combine_supp()")
 }
diff --git a/inst/WORDLIST b/inst/WORDLIST
index 885171f..1504941 100644
--- a/inst/WORDLIST
+++ b/inst/WORDLIST
@@ -25,7 +25,10 @@ datetime
 ddd
 difftime
 ggplots
+hms
 https
+lubridate
 trimws
 wikipedia
+ymd
 yyyy
diff --git a/man/import_sdtm.Rd b/man/import_sdtm.Rd
index eac4fd3..2b8e35b 100644
--- a/man/import_sdtm.Rd
+++ b/man/import_sdtm.Rd
@@ -10,6 +10,8 @@ import_sdtm(
   path,
   extension_choice = c(".sas7bdat", ".xpt"),
   ignore_case = TRUE,
+  auto_supp = FALSE,
+  auto_dtc = FALSE,
   ...
 )
 
@@ -33,6 +35,11 @@ and a warning will be given for subsequent files.}
 
 \item{ignore_case}{Passed to \code{list.files} when loading a directory.}
 
+\item{auto_supp}{Automatically combine --SUPP data with the main SDTM domain
+and remove the --SUPP data from the returned list of data.frames.}
+
+\item{auto_dtc}{Automatically convert --DTC columns to date/times?}
+
 \item{...}{Arguments passed to \code{rio::import}}
 
 \item{ignore_filename}{A vector of filenames not to load (case sensitive,
diff --git a/man/merge_supp.Rd b/man/merge_supp.Rd
index 12d058a..61e7867 100644
--- a/man/merge_supp.Rd
+++ b/man/merge_supp.Rd
@@ -4,33 +4,11 @@
 \alias{merge_supp}
 \title{Merge a supplementary dataset into a primary dataset}
 \usage{
-merge_supp(
-  primary,
-  supplementary,
-  remove_attributes = c("label"),
-  auto_convert = FALSE
-)
+merge_supp(...)
 }
 \arguments{
-\item{primary}{the data.frame of the primary dataset}
-
-\item{supplementary}{the data.frame of the supplementary dataset}
-
-\item{remove_attributes}{If \code{TRUE}, remove all attributes from all
-columns (this will break many classes); if \code{FALSE}, remove no
-attributes from any columns; if a character, remove those attributes from
-the columns.}
-
-\item{auto_convert}{should the data be automatically converted using
-`type_convert()`?}
-}
-\value{
-\code{primary} merged with \code{supplementary} where new column
-  names come from the \code{QNAM} column in \code{supplementary}
+\item{...}{Ignored}
 }
 \description{
-Merge a supplementary dataset into a primary dataset
-}
-\seealso{
-\code{\link{supp_reformat}}
+This function is defunct. Use `metatools::combine_supp()` instead.
 }
diff --git a/man/sdtm_dtc_to_datetime.Rd b/man/sdtm_dtc_to_datetime.Rd
index 21ccd4d..8437fa4 100644
--- a/man/sdtm_dtc_to_datetime.Rd
+++ b/man/sdtm_dtc_to_datetime.Rd
@@ -3,6 +3,9 @@
 \name{sdtm_dtc_to_datetime}
 \alias{sdtm_dtc_to_datetime}
 \alias{sdtm_dtc_to_datetime.list}
+\alias{sdtm_dtc_to_datetime.Date}
+\alias{sdtm_dtc_to_datetime.POSIXt}
+\alias{sdtm_dtc_to_datetime.character}
 \alias{sdtm_dtc_to_datetime.data.frame}
 \title{Convert the character representation of the date in an original SDTM dataset
 to a POSIXct object.}
@@ -11,16 +14,25 @@ sdtm_dtc_to_datetime(x, ...)
 
 \method{sdtm_dtc_to_datetime}{list}(x, ...)
 
-\method{sdtm_dtc_to_datetime}{data.frame}(x, date_col_pattern = "DTC$", truncated = 5, ...)
+\method{sdtm_dtc_to_datetime}{Date}(x, ...)
+
+\method{sdtm_dtc_to_datetime}{POSIXt}(x, ...)
+
+\method{sdtm_dtc_to_datetime}{character}(x, truncated = 5, ...)
+
+\method{sdtm_dtc_to_datetime}{data.frame}(x, date_col_pattern = "DTC$", ...)
 }
 \arguments{
 \item{x}{The data to convert}
 
-\item{...}{Additional arguments passed to \code{lubridate::ymd_hms}}
+\item{...}{Additional arguments passed to `lubridate::ymd_hms()` or
+`lubridate::ymd()`}
 
-\item{date_col_pattern}{A regex to search column names for dates to convert.}
+\item{truncated}{Passed to `lubridate::ymd_hms()` or `lubridate::ymd()`; the
+`truncated` argument is always considered relative to `ymd_hms` formatting,
+so it is used as `truncated - 3` for dates.}
 
-\item{truncated}{Passed to \code{lubridate::ymd_hms}}
+\item{date_col_pattern}{A regex to search column names for dates to convert.}
 }
 \value{
 The data with the date converted.  Note that all dates will be
diff --git a/man/strip_attributes.Rd b/man/strip_attributes.Rd
deleted file mode 100644
index 522824d..0000000
--- a/man/strip_attributes.Rd
+++ /dev/null
@@ -1,31 +0,0 @@
-% Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/merge_supp.R
-\name{strip_attributes}
-\alias{strip_attributes}
-\alias{strip_attributes.data.frame}
-\alias{strip_attributes.default}
-\title{Remove attributes from an object}
-\usage{
-strip_attributes(x, specific = NULL, ...)
-
-\method{strip_attributes}{data.frame}(x, specific = NULL, columns_only = TRUE, ...)
-
-\method{strip_attributes}{default}(x, specific = NULL, ...)
-}
-\arguments{
-\item{x}{The object to remove attributes from}
-
-\item{specific}{If \code{NULL}, all attributes are removed.  If a character
-vector, only the named attributes are removed.}
-
-\item{...}{Passed to other `strip_attributes()` methods.}
-
-\item{columns_only}{Do not strip attributes from the data.frame; only strip
-them from the columns of the data.frame.}
-}
-\value{
-\code{x} with fewer attributes.
-}
-\description{
-Remove attributes from an object
-}
diff --git a/man/supp_reformat.Rd b/man/supp_reformat.Rd
deleted file mode 100644
index 29f58f9..0000000
--- a/man/supp_reformat.Rd
+++ /dev/null
@@ -1,26 +0,0 @@
-% Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/merge_supp.R
-\name{supp_reformat}
-\alias{supp_reformat}
-\title{Reformat a --SUPP SDTM domain into a list of data.frames ready for merging
-into the primary domain.}
-\usage{
-supp_reformat(x, auto_convert = FALSE)
-}
-\arguments{
-\item{x}{a --SUPP SDTM domain object}
-
-\item{auto_convert}{should the data be automatically converted using
-`type_convert()`?}
-}
-\value{
-A list with length the same as \code{unique(x$IDVAR)} with
-  data.frames ready for merging into the primary dataset.
-}
-\description{
-Reformat a --SUPP SDTM domain into a list of data.frames ready for merging
-into the primary domain.
-}
-\seealso{
-\code{\link{merge_supp}}
-}
diff --git a/tests/testthat/example-sdtm/dm.xpt b/tests/testthat/example-sdtm/dm.xpt
new file mode 100644
index 0000000..a0b79cc
Binary files /dev/null and b/tests/testthat/example-sdtm/dm.xpt differ
diff --git a/tests/testthat/example-sdtm/suppdm.xpt b/tests/testthat/example-sdtm/suppdm.xpt
new file mode 100644
index 0000000..342704d
Binary files /dev/null and b/tests/testthat/example-sdtm/suppdm.xpt differ
diff --git a/tests/testthat/test-date_conversion.R b/tests/testthat/test-date_conversion.R
index ccb3a22..56a5509 100644
--- a/tests/testthat/test-date_conversion.R
+++ b/tests/testthat/test-date_conversion.R
@@ -1,3 +1,12 @@
+test_that("sdtm_dtc_to_datetime", {
+  expect_message(
+    ld_sdtm <- import_sdtm(path = test_path("example-sdtm"), auto_dtc = TRUE),
+    regexp = "Detected domain SUPPDM from data."
+  )
+  expect_s3_class(ld_sdtm$DM$RFPENDTC, "POSIXt")
+  expect_s3_class(ld_sdtm$DM$RFSTDTC, "Date")
+})
+
 test_that("generate_dtc works", {
   expect_equal(
     generate_dtc(datetime="2020-05-01T01:02:03"),
diff --git a/tests/testthat/test-defunct.R b/tests/testthat/test-defunct.R
new file mode 100644
index 0000000..4b970ba
--- /dev/null
+++ b/tests/testthat/test-defunct.R
@@ -0,0 +1,3 @@
+test_that("Defunct function notifications", {
+  lifecycle::expect_defunct(merge_supp())
+})
diff --git a/tests/testthat/test-import_sdtm.R b/tests/testthat/test-import_sdtm.R
new file mode 100644
index 0000000..6107919
--- /dev/null
+++ b/tests/testthat/test-import_sdtm.R
@@ -0,0 +1,43 @@
+# This is how the example SDTM data were created
+# rio::export(x = pharmaversesdtm::dm, file = test_path("example-sdtm/dm.xpt"))
+# rio::export(x = pharmaversesdtm::suppdm, file = test_path("example-sdtm/suppdm.xpt"))
+
+test_that("import_sdtm", {
+  # Automatically import a directory
+  expect_message(
+    import_sdtm(path = test_path("example-sdtm")),
+    regexp = "Detected domain SUPPDM from data."
+  )
+
+  # Import a single file
+  expect_message(
+    import_sdtm(path = test_path("example-sdtm/dm.xpt")),
+    regexp = "Detected domain DM from data."
+  )
+})
+
+test_that("import_sdtm expected errors", {
+  expect_error(
+    import_sdtm(path = "foo"),
+    regexp = 'The following were not found as directories or files: "foo"'
+  )
+  expect_error(
+    suppressMessages(import_sdtm(path = test_path("example-sdtm/suppdm.xpt"), auto_supp = TRUE)),
+    regexp = "Domain DM was not found when trying to auto-combine --SUPP data with SUPPDM"
+  )
+})
+
+test_that("import_sdtm auto_supp automatically merges --SUPP domains", {
+  expect_message(
+    ld_sdtm <- import_sdtm(path = test_path("example-sdtm")),
+    regexp = "Detected domain SUPPDM from data."
+  )
+  expect_named(ld_sdtm, c("DM", "SUPPDM"))
+
+  expect_message(
+    ld_sdtm <- import_sdtm(path = test_path("example-sdtm"), auto_supp = TRUE),
+    regexp = "Detected domain SUPPDM from data."
+  )
+  expect_named(ld_sdtm, "DM")
+})
+