gitserver: grpc: create proto roundtrip tests for GetObject[Request/Response] (#62564)

Closes https://github.com/sourcegraph/sourcegraph/issues/60411

We didn't have any round trip tests for the GetCommit request or response type. This PR adds them.

## Test plan

New unit tests

internal/gitserver/protocol/BUILD.bazel

@@ -32,6 +32,7 @@ go_test(
     embed = [":protocol"],
     deps = [
         "//internal/api",
+        "//internal/gitserver/gitdomain",
         "//internal/search/result",
         "@com_github_google_go_cmp//cmp",
         "@com_github_stretchr_testify//require",

internal/gitserver/protocol/gitserver.go

@@ -543,7 +543,6 @@ func (r *GetObjectResponse) FromProto(p *proto.GetObjectResponse) {
 	*r = GetObjectResponse{
 		Object: gitObj,
 	}
-
 }
 
 // IsPerforcePathCloneableRequest is the request to check if a Perforce path is cloneable.

internal/gitserver/protocol/gitserver_test.go

@@ -1,6 +1,8 @@
 package protocol
 
 import (
+	"math/rand"
+	"reflect"
 	"testing"
 	"testing/quick"
 	"time"
@@ -9,6 +11,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/sourcegraph/sourcegraph/internal/api"
+	"github.com/sourcegraph/sourcegraph/internal/gitserver/gitdomain"
 	"github.com/sourcegraph/sourcegraph/internal/search/result"
 )
 
@@ -79,3 +82,60 @@ func TestCommitMatchProtoRoundtrip(t *testing.T) {
 	roundtripped := CommitMatchFromProto(protoReq)
 	require.Equal(t, req, roundtripped)
 }
+
+func TestGetObjectRequestProtoRoundtrip(t *testing.T) {
+	var diff string
+
+	fn := func(original GetObjectRequest) bool {
+		protoReq := original.ToProto()
+
+		var converted GetObjectRequest
+		converted.FromProto(protoReq)
+
+		if diff = cmp.Diff(original, converted); diff != "" {
+			return false
+		}
+
+		return true
+	}
+
+	if err := quick.Check(fn, nil); err != nil {
+		t.Errorf("GetObjectRequest proto roundtrip failed (-want +got):\n%s", diff)
+	}
+}
+
+func TestGetObjectResponseProtoRoundtrip(t *testing.T) {
+	var diff string
+
+	fn := func(id [20]byte, typ fuzzObjectType) bool {
+		original := GetObjectResponse{
+			Object: gitdomain.GitObject{
+				ID:   id,
+				Type: gitdomain.ObjectType(typ),
+			},
+		}
+		protoResp := original.ToProto()
+
+		var converted GetObjectResponse
+		converted.FromProto(protoResp)
+
+		if diff = cmp.Diff(original, converted); diff != "" {
+			return false
+		}
+
+		return true
+	}
+
+	if err := quick.Check(fn, nil); err != nil {
+		t.Errorf("GetObjectResponse proto roundtrip failed (-want +got):\n%s", diff)
+	}
+}
+
+type fuzzObjectType gitdomain.ObjectType
+
+func (fuzzObjectType) Generate(r *rand.Rand, _ int) reflect.Value {
+	validValues := []gitdomain.ObjectType{gitdomain.ObjectTypeCommit, gitdomain.ObjectTypeTag, gitdomain.ObjectTypeTree, gitdomain.ObjectTypeBlob}
+	return reflect.ValueOf(fuzzObjectType(validValues[r.Intn(len(validValues))]))
+}
+
+var _ quick.Generator = fuzzObjectType(gitdomain.ObjectTypeCommit)