add integTest case for webhook empty response

Signed-off-by: Hailong Cui <ihailong@amazon.com>

notifications/notifications/build.gradle

@@ -230,6 +230,12 @@ integTest {
             excludeTestsMatching "org.opensearch.integtest.bwc.*IT"
         }
     }
+
+    if (usingRemoteCluster) {
+        filter {
+            excludeTestsMatching "org.opensearch.integtest.send.SendTestMessageWithMockServerIT"
+        }
+    }
 }
 
 project.getTasks().getByName("bundlePlugin").dependsOn(findProject(":${rootProject.name}-core").tasks.getByPath(":${rootProject.name}-core:bundlePlugin"))

notifications/notifications/src/test/kotlin/org/opensearch/integtest/send/SendTestMessageWithMockServerIT.kt

@@ -0,0 +1,81 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.integtest.send
+
+import com.google.gson.JsonArray
+import com.google.gson.JsonObject
+import com.sun.net.httpserver.HttpServer
+import org.junit.AfterClass
+import org.junit.Assert
+import org.junit.BeforeClass
+import org.opensearch.integtest.PluginRestTestCase
+import org.opensearch.notifications.NotificationPlugin.Companion.PLUGIN_BASE_URI
+import org.opensearch.rest.RestRequest
+import org.opensearch.rest.RestStatus
+import java.net.InetAddress
+import java.net.InetSocketAddress
+
+internal class SendTestMessageWithMockServerIT : PluginRestTestCase() {
+
+    fun `test webhook return with empty entity`() {
+        val url = "http://${server.address.hostString}:${server.address.port}/webhook"
+        logger.info("webhook url = {}", url)
+        // Create webhook notification config
+        val createRequestJsonString = """
+        {
+            "config":{
+                "name":"this is a sample config name",
+                "description":"this is a sample config description",
+                "config_type":"webhook",
+                "is_enabled":true,
+                "webhook":{
+                    "url":"$url",
+                    "header_params": {
+                       "Content-type": "text/plain"
+                    }
+                }
+            }
+        }
+        """.trimIndent()
+        val configId = createConfigWithRequestJsonString(createRequestJsonString)
+        Assert.assertNotNull(configId)
+        Thread.sleep(1000)
+
+        // send test message
+        val sendResponse = executeRequest(
+            RestRequest.Method.POST.name, "$PLUGIN_BASE_URI/feature/test/$configId", "", RestStatus.OK.status
+        )
+
+        logger.info(sendResponse)
+
+        // verify failure response is with message
+        val deliveryStatus = (sendResponse.get("status_list") as JsonArray).get(0).asJsonObject
+            .get("delivery_status") as JsonObject
+        Assert.assertEquals(deliveryStatus.get("status_code").asString, "200")
+        Assert.assertEquals(deliveryStatus.get("status_text").asString, "{}")
+    }
+
+    companion object {
+        private lateinit var server: HttpServer
+
+        @JvmStatic
+        @BeforeClass
+        fun setupWebhook() {
+            server = HttpServer.create(InetSocketAddress(InetAddress.getLoopbackAddress(), 0), 0)
+
+            server.createContext("/webhook") {
+                it.sendResponseHeaders(200, -1)
+            }
+            server.start()
+        }
+
+        @JvmStatic
+        @AfterClass
+        fun stopMockServer() {
+            server.stop(1)
+        }
+    }
+}