rename prommetric to prometheous, add unit tests

zrpc/internal/serverinterceptors/prometheousinterceptor_test.go

@@ -0,0 +1,19 @@
+package serverinterceptors
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"google.golang.org/grpc"
+)
+
+func TestUnaryPromMetricInterceptor(t *testing.T) {
+	interceptor := UnaryPrometheousInterceptor()
+	_, err := interceptor(context.Background(), nil, &grpc.UnaryServerInfo{
+		FullMethod: "/",
+	}, func(ctx context.Context, req interface{}) (interface{}, error) {
+		return nil, nil
+	})
+	assert.Nil(t, err)
+}