From 5770b1527035d4b9f5540e60e249cbc5745dfd42 Mon Sep 17 00:00:00 2001
From: RedlineTriad <39059512+RedlineTriad@users.noreply.github.com>
Date: Sat, 10 Oct 2020 07:30:48 +0200
Subject: [PATCH] Use iterator chain instead of string concat. (#2655)

* Use iterator chain instead of string concat

* Add regression test for multi-value lines
---
 crates/nu-cli/src/commands/lines.rs       |  6 +++---
 crates/nu-cli/tests/commands/lines.rs     | 15 +++++++++++++++
 tests/fixtures/formats/sample-simple.json |  4 ++++
 3 files changed, 22 insertions(+), 3 deletions(-)
 create mode 100644 tests/fixtures/formats/sample-simple.json

diff --git a/crates/nu-cli/src/commands/lines.rs b/crates/nu-cli/src/commands/lines.rs
index 5b6f163493..2b486a0cac 100644
--- a/crates/nu-cli/src/commands/lines.rs
+++ b/crates/nu-cli/src/commands/lines.rs
@@ -75,9 +75,9 @@ async fn lines(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputSt
                 } => {
                     let mut leftover_string = leftover_string.lock();
 
-                    let st = (&*leftover_string).clone() + &st;
-
-                    let mut lines: Vec<String> = st.lines().map(|x| x.to_string()).collect();
+                    let lo_lines = (&*leftover_string).lines().map(|x| x.to_string());
+                    let st_lines = st.lines().map(|x| x.to_string());
+                    let mut lines: Vec<String> = lo_lines.chain(st_lines).collect();
 
                     leftover_string.clear();
 
diff --git a/crates/nu-cli/tests/commands/lines.rs b/crates/nu-cli/tests/commands/lines.rs
index 6f394fad87..efb77ea77b 100644
--- a/crates/nu-cli/tests/commands/lines.rs
+++ b/crates/nu-cli/tests/commands/lines.rs
@@ -34,3 +34,18 @@ fn lines_proper_buffering() {
 
     assert_eq!(actual.out, "[8194,4]");
 }
+
+#[test]
+fn lines_multi_value_split() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            open sample-simple.json
+            | get first second
+            | lines
+            | count
+        "#
+    ));
+
+    assert_eq!(actual.out, "6");
+}
diff --git a/tests/fixtures/formats/sample-simple.json b/tests/fixtures/formats/sample-simple.json
new file mode 100644
index 0000000000..7986b6e546
--- /dev/null
+++ b/tests/fixtures/formats/sample-simple.json
@@ -0,0 +1,4 @@
+{
+    "first": "first",
+    "second": "this\nshould\nbe\nseparate\nlines"
+}
\ No newline at end of file