From 632a538eb3aadd03e91792aa079fccc7ae5f96f4 Mon Sep 17 00:00:00 2001
From: Alexey <alex.esprit@gmail.com>
Date: Sat, 29 Feb 2020 17:25:31 +0300
Subject: [PATCH] string: update `string.repeat` behavior

Panic if a repeat count is negative.
Return an empty string if a repeat count is zero.
---
 vlib/builtin/string.v      |  6 +++++-
 vlib/builtin/string_test.v | 14 +++++++++-----
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/vlib/builtin/string.v b/vlib/builtin/string.v
index b1e8232476..4f26446c7f 100644
--- a/vlib/builtin/string.v
+++ b/vlib/builtin/string.v
@@ -1251,7 +1251,11 @@ pub fn (s string) bytes() []byte {
 
 // repeat returns a new string with a specified number of copies of the string it was called on.
 pub fn (s string) repeat(count int) string {
-	if count <= 1 {
+	if count < 0 {
+		panic('string.repeat: count is negative: $count')
+	} else if count == 0 {
+		return ''
+	} else if count == 1 {
 		return s
 	}
 	mut ret := malloc(s.len * count + 1)
diff --git a/vlib/builtin/string_test.v b/vlib/builtin/string_test.v
index 44b6209a77..3b1c1f225c 100644
--- a/vlib/builtin/string_test.v
+++ b/vlib/builtin/string_test.v
@@ -603,11 +603,15 @@ fn test_limit() {
 }
 
 fn test_repeat() {
-	s := 'V! '
-	assert s.repeat(5) == 'V! V! V! V! V! '
-	assert s.repeat(1) == s
-	assert s.repeat(0) == s
-	assert s.repeat(-1) == s
+	s1 := 'V! '
+	assert s1.repeat(5) == 'V! V! V! V! V! '
+	assert s1.repeat(1) == s1
+	assert s1.repeat(0) == ''
+	s2 := ''
+	assert s2.repeat(5) == s2
+	assert s2.repeat(1) == s2
+	assert s2.repeat(0) == s2
+	// TODO Add test for negative values
 }
 
 fn test_raw() {