Add file arguement to print function

R/diffdf.R

@@ -370,24 +370,7 @@ diffdf <- function(
 
 
     if (!is.null(file)) {
-        x <- print(COMPARE, as_string = TRUE)
-
-        tryCatch(
-            {
-                sink(file)
-                cat(x, sep = "\n")
-                sink()
-            },
-            warning = function(w) {
-                sink()
-                warning(w)
-            },
-            error = function(e) {
-                sink()
-                stop(e)
-            }
-        )
-        return(invisible(COMPARE))
+        print(COMPARE, file = file)
     }
 
     return(COMPARE)
@@ -415,7 +398,7 @@ diffdf <- function(
 #' @export
 diffdf_has_issues <- function(x) {
     if (class(x)[[1]] != "diffdf") stop("x is not an diffdf object")
-    return(length(x) != 0)
+    length(x) != 0
 }
 
 

R/print.R

@@ -1,18 +1,26 @@
 #' Print diffdf objects
 #'
-#' Print nicely formatted version of an diffdf object
-#' @param x comparison object created by diffdf().
-#' @param ... Additional arguments (not used)
-#' @param row_limit Max row limit for difference tables (NULL to show all rows)
-#' @param as_string Return printed message as an R character vector?
+#' Print a nicely formatted version of a diffdf object.
+#'
+#' @param x A comparison object created by \code{diffdf()}.
+#' @param ... Additional arguments (not used).
+#' @param row_limit Maximum number of rows to display in difference tables.
+#' Use \code{NULL} to show all rows. Default is 10.
+#' @param as_string Logical. If \code{TRUE}, returns the printed message as an R
+#' character vector instead of printing to the console. Default is \code{FALSE}.
+#' @param file A connection or a character string naming the file to print to. If
+#' \code{NULL} (the default), output is printed to the console.
+#'
 #' @examples
 #' x <- subset(iris, -Species)
 #' x[1, 2] <- 5
 #' COMPARE <- diffdf(iris, x)
 #' print(COMPARE)
 #' print(COMPARE, row_limit = 5)
+#' print(COMPARE, file = "output.txt")
+#'
 #' @export
-print.diffdf <- function(x, row_limit = 10, as_string = FALSE, ...) {
+print.diffdf <- function(x, row_limit = 10, as_string = FALSE, file = NULL, ...) {
     if (!is.null(row_limit)) {
         assertthat::assert_that(
             assertthat::is.number(row_limit),
@@ -33,8 +41,29 @@ print.diffdf <- function(x, row_limit = 10, as_string = FALSE, ...) {
         end_text <- paste0(unlist(end_text), collapse = "")
         outtext <- paste0(start_text, end_text)
     }
+
+    string_content <- strsplit(outtext, "\n")[[1]]
+    if (!is.null(file)) {
+        tryCatch(
+            {
+                sink(file)
+                cat(string_content, sep = "\n")
+                sink()
+            },
+            warning = function(w) {
+                sink()
+                warning(w)
+            },
+            error = function(e) {
+                sink()
+                stop(e)
+            }
+        )
+        return(invisible(COMPARE))
+    }
+
     if (as_string) {
-        return(strsplit(outtext, "\n")[[1]])
+        return(string_content)
     } else {
         cat(outtext)
         return(invisible(COMPARE))

tests/testthat/test-print_output.R

@@ -117,3 +117,43 @@ test_that("print.diffdf errors when given bad inputs", {
         print(diff, as_string = c(TRUE, TRUE)),
     )
 })
+
+
+test_that("#135 - Writing to file works as expected with row limits", {
+    f1 <- withr::local_tempfile()
+    f2 <- withr::local_tempfile()
+
+    x2 <- diffdf(
+        list_of_comparisons[[5]][[1]],
+        list_of_comparisons[[5]][[2]],
+        suppress_warnings = TRUE,
+        file = f1
+    )
+
+    expect_equal(
+        readLines(f1),
+        print(x2, as_string = TRUE)
+    )
+
+    print(x2, file = f2)
+    expect_equal(
+        readLines(f1),
+        readLines(f2)
+    )
+
+
+
+    f3 <- withr::local_tempfile()
+
+    d1 <- tibble(id = seq_len(30), x = 1)
+    d2 <- tibble(id = seq_len(30), x = 0)
+
+    x2 <- diffdf(d1, d2, suppress_warnings = TRUE)
+    print(x2, file = f3, row_limit = 5)
+
+    expect_equal(
+        readLines(f3),
+        print(x2, as_string = TRUE, row_limit = 5)
+    )
+
+})