add private option to set meterprovider

Author: dashpole

sdk/trace/batch_span_processor.go

@@ -77,6 +77,9 @@ type BatchSpanProcessorOptions struct {
 	// Blocking option should be used carefully as it can severely affect the performance of an
 	// application.
 	BlockOnQueueFull bool
+
+	// meterProvider is the meterProvider used to record self-observability metrics.
+	meterProvider metric.MeterProvider
 }
 
 // batchSpanProcessor is a SpanProcessor that batches asynchronously-received
@@ -349,6 +352,16 @@ func WithBlocking() BatchSpanProcessorOption {
 	}
 }
 
+// withMeterProvider allows configuring the meterProvider used for recording
+// self-observability metrics during testing.
+func withMeterProvider(provider metric.MeterProvider) BatchSpanProcessorOption {
+	return func(o *BatchSpanProcessorOptions) {
+		if provider != nil {
+			o.meterProvider = provider
+		}
+	}
+}
+
 // exportSpans is a subroutine of processing and draining the queue.
 func (bsp *batchSpanProcessor) exportSpans(ctx context.Context) error {
 	bsp.timer.Reset(bsp.o.BatchTimeout)