From f985833dec19b0147db3c5c33d3bf0181891d458 Mon Sep 17 00:00:00 2001 From: "Bryan C. Mills" Date: Wed, 16 Feb 2022 10:52:01 -0500 Subject: [PATCH] testing: panic in Fuzz if the function returns a value MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Otherwise, the behavior of a fuzz target that returns an error could be confusing. Fuzz is already documented to require a function “with no return value”, so this fixes the implementation to match the existing documentation. Fixes #51222 Change-Id: I44ca7ee10960214c92f5ac066ac8484c8bb9cd6f Reviewed-on: https://go-review.googlesource.com/c/go/+/386175 Trust: Bryan Mills Run-TryBot: Bryan Mills Reviewed-by: Robert Findley Reviewed-by: Nooras Saba‎ TryBot-Result: Gopher Robot --- .../go/testdata/script/test_fuzz_return.txt | 19 +++++++++++++++++++ src/testing/fuzz.go | 3 +++ 2 files changed, 22 insertions(+) create mode 100644 src/cmd/go/testdata/script/test_fuzz_return.txt diff --git a/src/cmd/go/testdata/script/test_fuzz_return.txt b/src/cmd/go/testdata/script/test_fuzz_return.txt new file mode 100644 index 0000000000..63275aad01 --- /dev/null +++ b/src/cmd/go/testdata/script/test_fuzz_return.txt @@ -0,0 +1,19 @@ +[short] skip + +! go test . +stdout '^panic: testing: fuzz target must not return a value \[recovered\]$' + +-- go.mod -- +module test +go 1.18 +-- x_test.go -- +package test + +import "testing" + +func FuzzReturnErr(f *testing.F) { + f.Add("hello, validation!") + f.Fuzz(func(t *testing.T, in string) string { + return in + }) +} diff --git a/src/testing/fuzz.go b/src/testing/fuzz.go index e1d7544f7a..b5e1339deb 100644 --- a/src/testing/fuzz.go +++ b/src/testing/fuzz.go @@ -227,6 +227,9 @@ func (f *F) Fuzz(ff any) { if fnType.NumIn() < 2 || fnType.In(0) != reflect.TypeOf((*T)(nil)) { panic("testing: fuzz target must receive at least two arguments, where the first argument is a *T") } + if fnType.NumOut() != 0 { + panic("testing: fuzz target must not return a value") + } // Save the types of the function to compare against the corpus. var types []reflect.Type -- 2.48.1