let find take linebreaks into account in Value::String (#7789)

# Description

Fixes #7774. The functionality should be the same as feeding all
`PipelineDate::Value(Value::String(_,_),_)` into `lines` before putting
it into `find`.

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

crates/nu-command/src/filters/find.rs

@@ -8,8 +8,8 @@ use nu_engine::{env_to_string, CallExt};
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, Config, Example, IntoInterruptiblePipelineData, ListStream, PipelineData, ShellError,
-    Signature, Span, SyntaxShape, Type, Value,
+    Category, Config, Example, IntoInterruptiblePipelineData, IntoPipelineData, ListStream,
+    PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 use nu_utils::get_ls_colors;
 
@@ -150,6 +150,7 @@ impl Command for Find {
         if let Some(regex) = regex {
             find_with_regex(regex, engine_state, stack, call, input)
         } else {
+            let input = split_string_if_multiline(input);
             find_with_rest_and_highlight(engine_state, stack, call, input)
         }
     }
@@ -591,3 +592,28 @@ mod tests {
         test_examples(Find)
     }
 }
+
+fn split_string_if_multiline(input: PipelineData) -> PipelineData {
+    match input {
+        PipelineData::Value(Value::String { ref val, span }, _) => {
+            if val.contains('\n') {
+                Value::List {
+                    vals: {
+                        val.lines()
+                            .map(|s| Value::String {
+                                val: s.to_string(),
+                                span,
+                            })
+                            .collect()
+                    },
+                    span,
+                }
+                .into_pipeline_data()
+                .set_metadata(input.metadata())
+            } else {
+                input
+            }
+        }
+        _ => input,
+    }
+}

crates/nu-command/tests/commands/find.rs

@@ -109,3 +109,15 @@ fn find_with_filepath_search_with_multiple_patterns() {
         assert_eq!(actual.out, r#"["amigos.txt","arepas.clu"]"#);
     })
 }
+
+#[test]
+fn find_takes_into_account_linebreaks_in_string() {
+    let actual = nu!(
+    cwd: ".", pipeline(
+    r#"
+        "atest\nanothertest\nnohit\n" | find a | length
+        "#
+    ));
+
+    assert_eq!(actual.out, "2");
+}