From 4a9e01b0bce380619779d099d9f1dbaad7f1c568 Mon Sep 17 00:00:00 2001
From: Patrick Marks <patrick@10xgenomics.com>
Date: Fri, 15 May 2020 09:09:07 -0700
Subject: [PATCH] ensure that validation failure error message includes a
 newline. also add a basic test of a failed validation

---
 src/parse/errors.rs |  1 +
 tests/validators.rs | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/parse/errors.rs b/src/parse/errors.rs
index 8da0bf87..ace794c8 100644
--- a/src/parse/errors.rs
+++ b/src/parse/errors.rs
@@ -851,6 +851,7 @@ impl Error {
         }
 
         c.none(&format!(": {}", err))?;
+        try_help(&mut c)?;
 
         Ok(Error {
             cause: format!(
diff --git a/tests/validators.rs b/tests/validators.rs
index 31e7186d..8914eefc 100644
--- a/tests/validators.rs
+++ b/tests/validators.rs
@@ -17,3 +17,22 @@ fn both_validator_and_validator_os() {
         )
         .try_get_matches_from(&["app", "1"]);
 }
+
+#[test]
+fn test_validator_msg_newline() {
+    let res = App::new("test")
+        .arg(Arg::new("test").validator(|val| val.parse::<u32>().map_err(|e| e.to_string())))
+        .try_get_matches_from(&["app", "f"]);
+
+    assert!(res.is_err());
+    let err = res.unwrap_err();
+
+    assert_eq!(
+        err.cause,
+        "Invalid value for \'<test>\': invalid digit found in string"
+    );
+
+    // This message is the only thing that gets printed -- make sure it ends with a newline
+    let msg = format!("{}", err);
+    assert!(msg.ends_with('\n'));
+}