preserve reused code

internal/api/grpc/fields.go

@@ -0,0 +1,36 @@
+package grpc
+
+import (
+	"testing"
+
+	"google.golang.org/protobuf/reflect/protoreflect"
+)
+
+// AllFieldsSet recusively checks if all values in a message
+// have a non-zero value.
+func AllFieldsSet(t testing.TB, msg protoreflect.Message, ignoreTypes ...protoreflect.FullName) {
+	ignore := make(map[protoreflect.FullName]bool, len(ignoreTypes))
+	for _, name := range ignoreTypes {
+		ignore[name] = true
+	}
+
+	md := msg.Descriptor()
+	name := md.FullName()
+	if ignore[name] {
+		return
+	}
+
+	fields := md.Fields()
+
+	for i := 0; i < fields.Len(); i++ {
+		fd := fields.Get(i)
+		if !msg.Has(fd) {
+			t.Errorf("not all fields set in %q, missing %q", name, fd.Name())
+			continue
+		}
+
+		if fd.Kind() == protoreflect.MessageKind {
+			AllFieldsSet(t, msg.Get(fd).Message(), ignoreTypes...)
+		}
+	}
+}

internal/command/command.go

@@ -141,11 +141,21 @@ func StartCommands(
 	return repo, nil
 }
 
-func AppendAndReduce(object interface {
+type AppendReducer interface {
 	AppendEvents(...eventstore.Event)
 	// TODO: Why is it allowed to return an error here?
 	Reduce() error
-}, events ...eventstore.Event) error {
+}
+
+func (c *Commands) pushAppendAndReduce(ctx context.Context, object AppendReducer, cmds ...eventstore.Command) error {
+	events, err := c.eventstore.Push(ctx, cmds...)
+	if err != nil {
+		return err
+	}
+	return AppendAndReduce(object, events...)
+}
+
+func AppendAndReduce(object AppendReducer, events ...eventstore.Event) error {
 	object.AppendEvents(events...)
 	return object.Reduce()
 }