From 09f3ff174c6487bebc4a9a6adea6d74baf6a92cc Mon Sep 17 00:00:00 2001
From: cui fliter <imcusg@gmail.com>
Date: Mon, 12 Sep 2022 15:50:04 +0000
Subject: [PATCH] strings: add a test case of growLen is negative

Before committing,  the test coverage of strings/builder.go is 97.4%
After committing,  the test coverage of strings/builder.go is 100%

Change-Id: I22643b1c4632b5ca7ef98362f32bb85faae80bad
GitHub-Last-Rev: 2a55ca3e33d3aabd2ccc047de580abcfe05d6bb4
GitHub-Pull-Request: golang/go#55004
Reviewed-on: https://go-review.googlesource.com/c/go/+/430156
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Jenny Rakoczy <jenny@golang.org>
---
 src/strings/builder_test.go | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/strings/builder_test.go b/src/strings/builder_test.go
index e3d239266f..dbc2c1943b 100644
--- a/src/strings/builder_test.go
+++ b/src/strings/builder_test.go
@@ -109,6 +109,15 @@ func TestBuilderGrow(t *testing.T) {
 			t.Errorf("growLen=%d: got %d allocs during Write; want %v", growLen, g, w)
 		}
 	}
+	// when growLen < 0, should panic
+	var a Builder
+	n := -1
+	defer func() {
+		if r := recover(); r == nil {
+			t.Errorf("a.Grow(%d) should panic()", n)
+		}
+	}()
+	a.Grow(n)
 }
 
 func TestBuilderWrite2(t *testing.T) {
-- 
2.50.0