Add test for admin topic creation (#1152)

### Motivation

Lacking tests for creating topic using pulsarAdmin

### Modifications

- Add test for admin topic creation

Author: RobertIndie

pulsaradmin/pkg/admin/topic_test.go

@@ -0,0 +1,55 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package admin
+
+import (
+	"testing"
+
+	"github.com/apache/pulsar-client-go/pulsaradmin/pkg/admin/config"
+	"github.com/apache/pulsar-client-go/pulsaradmin/pkg/utils"
+)
+
+func TestCreateTopic(t *testing.T) {
+	checkError := func(err error) {
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	cfg := &config.Config{}
+	admin, err := New(cfg)
+	checkError(err)
+
+	topic := "persistent://public/default/testCreateTopic"
+
+	topicName, err := utils.GetTopicName(topic)
+	checkError(err)
+
+	err = admin.Topics().Create(*topicName, 0)
+	checkError(err)
+
+	topicLists, err := admin.Namespaces().GetTopics("public/default")
+	checkError(err)
+
+	for _, t := range topicLists {
+		if t == topic {
+			return
+		}
+	}
+	t.Error("Couldn't find topic: " + topic)
+}