proto: move explicit test as a seed into the fuzz test

fuzztest seeds are executed as part of `go test` so there is no need for
an explicit test and having this as a seed in the fuzztest is sufficient
to get test coverage for this case.

Change-Id: Ia4a2d721e544e1a1ad0ad3ef9aa9d0af6bfe2db8
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/567755
Auto-Submit: Lasse Folger <lassefolger@google.com>
Reviewed-by: Michael Stapelberg <stapelberg@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

proto/fuzz_test.go

@@ -19,22 +19,6 @@ import (
 	testfuzzpb "google.golang.org/protobuf/internal/testprotos/editionsfuzztest"
 )
 
-func TestUnmarshalInvalidGroupField(t *testing.T) {
-	in := []byte("\x82\x01\x010")
-	// Test proto2 proto
-	proto2Proto := &testfuzzpb.TestAllTypesProto2{}
-
-	if err := proto.Unmarshal(in, proto2Proto); err != nil {
-		t.Error(err)
-	}
-	// Test equivalent editions proto
-	editionsProto := &testfuzzpb.TestAllTypesProto2Editions{}
-
-	if err := proto.Unmarshal(in, editionsProto); err != nil {
-		t.Error(err)
-	}
-}
-
 // compareEquivalentProtos compares equivalent messages m0 and m1, where one is
 // typically a Protobuf Editions message and the other isn't. It unmarshals the
 // wireBytes into a message of type m0 and one of type m1 and compares the
@@ -87,13 +71,15 @@ func compareEquivalentProtos(t *testing.T, wireBytes []byte, m0, m1 proto.Messag
 
 func FuzzProto2EditionConversion(f *testing.F) {
 	f.Add([]byte("Hello World!"))
+	f.Add([]byte("\x82\x01\x010"))
 	f.Fuzz(func(t *testing.T, in []byte) {
 		compareEquivalentProtos(t, in, (*testfuzzpb.TestAllTypesProto2)(nil), (*testfuzzpb.TestAllTypesProto2Editions)(nil))
 	})
 }
 
 func FuzzProto3EditionConversion(f *testing.F) {
 	f.Add([]byte("Hello World!"))
+	f.Add([]byte("\x82\x01\x010"))
 	f.Fuzz(func(t *testing.T, in []byte) {
 		compareEquivalentProtos(t, in, (*testfuzzpb.TestAllTypesProto3)(nil), (*testfuzzpb.TestAllTypesProto3Editions)(nil))
 	})