From 4fb2614419bbe49963b9ed5cb0aceeb188334439 Mon Sep 17 00:00:00 2001
From: Maxim Devoir <maximdevoir@gmail.com>
Date: Wed, 13 Nov 2019 00:09:02 -0800
Subject: [PATCH] Gracefully handle non-string inputs (#9)

---
 index.d.ts      |  3 ++-
 index.js        |  2 +-
 index.test-d.ts |  5 +++++
 readme.md       |  4 ++--
 test.js         | 10 ++++++++++
 5 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/index.d.ts b/index.d.ts
index 76a858b..1f32fd2 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -17,9 +17,10 @@ declare const detectNewline: {
 	/**
 	Detect the dominant newline character of a string.
 
-	@returns Returns detected newline or `\n` when no newline character is found.
+	@returns The detected newline or `\n` when no newline character is found or the input is not a string.
 	*/
 	graceful(string: string): '\r\n' | '\n';
+	graceful(string?: unknown): '\n';
 };
 
 export = detectNewline;
diff --git a/index.js b/index.js
index 919598d..987ed87 100644
--- a/index.js
+++ b/index.js
@@ -18,4 +18,4 @@ const detectNewline = string => {
 };
 
 module.exports = detectNewline;
-module.exports.graceful = string => detectNewline(string) || '\n';
+module.exports.graceful = string => (typeof string === 'string' && detectNewline(string)) || '\n';
diff --git a/index.test-d.ts b/index.test-d.ts
index 9593f0f..13c7047 100644
--- a/index.test-d.ts
+++ b/index.test-d.ts
@@ -3,3 +3,8 @@ import detectNewline = require('.');
 
 expectType<'\r\n' | '\n' | undefined>(detectNewline('foo\nbar\nbaz\r\n'));
 expectType<'\r\n' | '\n'>(detectNewline.graceful('foo\nbar\nbaz\r\n'));
+expectType<'\n'>(detectNewline.graceful(null));
+expectType<'\n'>(detectNewline.graceful(undefined));
+expectType<'\n'>(detectNewline.graceful());
+expectType<'\n'>(detectNewline.graceful(1));
+expectType<'\n'>(detectNewline.graceful(['foo', 'bar']));
diff --git a/readme.md b/readme.md
index f1a1b9a..eee16c2 100644
--- a/readme.md
+++ b/readme.md
@@ -26,9 +26,9 @@ detectNewline('foo\nbar\nbaz\r\n');
 
 Returns the detected newline or `undefined` when no newline character is found.
 
-### detectNewline.graceful(string)
+### detectNewline.graceful(unknown)
 
-Returns the detected newline or `\n` when no newline character is found.
+Returns the detected newline or `\n` when no newline character is found or the input is not a string.
 
 
 ## Related
diff --git a/test.js b/test.js
index 8d0b183..15b4796 100644
--- a/test.js
+++ b/test.js
@@ -7,5 +7,15 @@ test('main', t => {
 	t.is(detectNewline('foo\nbar\nbaz\r\n'), '\n');
 	t.is(detectNewline('foo\nbar\r\n'), '\n');
 	t.is(detectNewline('foo'), undefined);
+});
+
+test('graceful', t => {
 	t.is(detectNewline.graceful('foo'), '\n');
+	t.is(detectNewline.graceful('foo\r\nbar\r\nbaz\n'), '\r\n');
+	t.is(detectNewline.graceful(null), '\n');
+	t.is(detectNewline.graceful(undefined), '\n');
+	t.is(detectNewline.graceful(), '\n');
+	t.is(detectNewline.graceful(0), '\n');
+	t.is(detectNewline.graceful(true), '\n');
+	t.is(detectNewline.graceful(['foo', 'bar']), '\n');
 });