From 834522d0022ef538ce8a7d96b380a4316c6e58ba Mon Sep 17 00:00:00 2001
From: Stefan Holderbach <sholderbach@users.noreply.github.com>
Date: Thu, 27 Oct 2022 23:45:45 +0200
Subject: [PATCH] Fix `each while` behavior when printing. (#6897)

Fixes #6895

Warning: `Iterator::map_while` does not return a `FusedIterator`!
Depending on the consuming adaptor or code (e.g. for loop) the iteration
may be stopped but this is not guaranteed.

Adds a test example but Examples handle iterators like
`FusedIterator` and thus don't catch the regression

Cleanup the message on another test
---
 crates/nu-command/src/filters/each_while.rs | 28 ++++++++++++++++++---
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/crates/nu-command/src/filters/each_while.rs b/crates/nu-command/src/filters/each_while.rs
index 468e961d4c..f0459cff29 100644
--- a/crates/nu-command/src/filters/each_while.rs
+++ b/crates/nu-command/src/filters/each_while.rs
@@ -36,24 +36,42 @@ impl Command for EachWhile {
     fn examples(&self) -> Vec<Example> {
         let stream_test_1 = vec![
             Value::Int {
-                val: 1,
+                val: 2,
                 span: Span::test_data(),
             },
             Value::Int {
-                val: 2,
+                val: 4,
+                span: Span::test_data(),
+            },
+        ];
+        let stream_test_2 = vec![
+            Value::String {
+                val: "Output: 1".into(),
+                span: Span::test_data(),
+            },
+            Value::String {
+                val: "Output: 2".into(),
                 span: Span::test_data(),
             },
         ];
 
         vec![
             Example {
-                example: "[1 2 3] | each while { |it| if $it < 3 { $it } else { null } }",
-                description: "Multiplies elements in list",
+                example: "[1 2 3] | each while { |it| if $it < 3 { $it * 2 } else { null } }",
+                description: "Multiplies elements below three by two",
                 result: Some(Value::List {
                     vals: stream_test_1,
                     span: Span::test_data(),
                 }),
             },
+            Example {
+                example: r#"[1 2 stop 3 4] | each while { |it| if $it == 'stop' { null } else { $"Output: ($it)" } }"#,
+                description: "Output elements till reaching 'stop'",
+                result: Some(Value::List {
+                    vals: stream_test_2,
+                    span: Span::test_data(),
+                }),
+            },
             Example {
                 example: r#"[1 2 3] | each while -n { |it| if $it.item < 2 { $"value ($it.item) at ($it.index)!"} else { null } }"#,
                 description: "Iterate over each element, print the matching value and its index",
@@ -140,6 +158,7 @@ impl Command for EachWhile {
                         Err(_) => None,
                     }
                 })
+                .fuse()
                 .into_pipeline_data(ctrlc)),
             PipelineData::ExternalStream { stdout: None, .. } => Ok(PipelineData::new(call.head)),
             PipelineData::ExternalStream {
@@ -198,6 +217,7 @@ impl Command for EachWhile {
                         Err(_) => None,
                     }
                 })
+                .fuse()
                 .into_pipeline_data(ctrlc)),
             PipelineData::Value(x, ..) => {
                 if let Some(var) = block.signature.get_positional(0) {