From d12f96d9ca5c72f573782b252e64aa43f9b82a4d Mon Sep 17 00:00:00 2001
From: Daniel Rocco <drocco@gmail.com>
Date: Fri, 2 Apr 2021 09:13:25 -0400
Subject: [PATCH] fold: preserve blank lines

---
 src/uu/fold/src/fold.rs    |  5 ++++-
 tests/by-util/test_fold.rs | 28 +++++++++++++++++++++++++++-
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/src/uu/fold/src/fold.rs b/src/uu/fold/src/fold.rs
index 05f0725ef..27ab319d0 100644
--- a/src/uu/fold/src/fold.rs
+++ b/src/uu/fold/src/fold.rs
@@ -100,7 +100,10 @@ fn fold(filenames: Vec<String>, bytes: bool, spaces: bool, width: usize) {
 fn fold_file<T: Read>(file: BufReader<T>, bytes: bool, spaces: bool, width: usize) {
     for line_result in file.lines() {
         let mut line = safe_unwrap!(line_result);
-        if bytes {
+
+        if line.is_empty() {
+            println!();
+        } else if bytes {
             let len = line.len();
             let mut i = 0;
             while i < len {
diff --git a/tests/by-util/test_fold.rs b/tests/by-util/test_fold.rs
index c17f300d2..64d77cd2b 100644
--- a/tests/by-util/test_fold.rs
+++ b/tests/by-util/test_fold.rs
@@ -25,9 +25,35 @@ fn test_40_column_word_boundary() {
 }
 
 #[test]
-fn test_default_warp_with_newlines() {
+fn test_default_wrap_with_newlines() {
     new_ucmd!()
         .arg("lorem_ipsum_new_line.txt")
         .run()
         .stdout_is_fixture("lorem_ipsum_new_line_80_column.expected");
 }
+
+#[test]
+fn test_should_preserve_empty_lines() {
+    new_ucmd!().pipe_in("\n").succeeds().stdout_is("\n");
+
+    new_ucmd!()
+        .arg("-w1")
+        .pipe_in("0\n1\n\n2\n\n\n")
+        .succeeds()
+        .stdout_is("0\n1\n\n2\n\n\n");
+}
+
+#[test]
+fn test_word_boundary_split_should_preserve_empty_lines() {
+    new_ucmd!()
+        .arg("-s")
+        .pipe_in("\n")
+        .succeeds()
+        .stdout_is("\n");
+
+    new_ucmd!()
+        .args(&["-w1", "-s"])
+        .pipe_in("0\n1\n\n2\n\n\n")
+        .succeeds()
+        .stdout_is("0\n1\n\n2\n\n\n");
+}