Added & fixed test cases for shrink action

Signed-off-by: Angie Zhang <[email protected]>

src/test/kotlin/org/opensearch/indexmanagement/indexstatemanagement/action/ShrinkActionIT.kt

@@ -55,7 +55,9 @@ class ShrinkActionIT : IndexStateManagementRestTestCase() {
             }
         """.trimIndent()
         val res = client().makeRequest(
-            "PUT", "_cluster/settings", emptyMap(),
+            "PUT",
+            "_cluster/settings",
+            emptyMap(),
             StringEntity(request, ContentType.APPLICATION_JSON)
         )
         assertEquals("Request failed", RestStatus.OK, res.restStatus())
@@ -447,7 +449,6 @@ class ShrinkActionIT : IndexStateManagementRestTestCase() {
         val indexName = "${testIndexName}_index_shard_noop"
         val policyID = "${testIndexName}_testPolicyName_shard_noop"
 
-        // Create a Policy with one State that only preforms a force_merge Action
         val shrinkAction = ShrinkAction(
             numNewShards = null,
             maxShardSize = null,
@@ -500,6 +501,63 @@ class ShrinkActionIT : IndexStateManagementRestTestCase() {
         }
     }
 
+    fun `test source index already has target number of shard`() {
+        val logger = LogManager.getLogger(::ShrinkActionIT)
+        val indexName = "${testIndexName}_index_shard_noop"
+        val policyID = "${testIndexName}_testPolicyName_shard_noop"
+
+        val shrinkAction = ShrinkAction(
+            numNewShards = 2,
+            maxShardSize = null,
+            percentageOfSourceShards = null,
+            targetIndexTemplate = Script(ScriptType.INLINE, Script.DEFAULT_TEMPLATE_LANG, "{{ctx.index}}$testIndexSuffix", mapOf()),
+            aliases = null,
+            forceUnsafe = true,
+            index = 0
+        )
+        val states = listOf(State("ShrinkState", listOf(shrinkAction), listOf()))
+
+        val policy = Policy(
+            id = policyID,
+            description = "$testIndexName description",
+            schemaVersion = 11L,
+            lastUpdatedTime = Instant.now().truncatedTo(ChronoUnit.MILLIS),
+            errorNotification = randomErrorNotification(),
+            defaultState = states[0].name,
+            states = states
+        )
+
+        createPolicy(policy, policyID)
+        createIndex(indexName, policyID, null, "0", "2", "")
+
+        insertSampleData(indexName, 3)
+
+        // Will change the startTime each execution so that it triggers in 2 seconds
+        // First execution: Policy is initialized
+        val managedIndexConfig = getExistingManagedIndexConfig(indexName)
+
+        updateManagedIndexConfigStartTime(managedIndexConfig)
+        waitFor(Instant.ofEpochSecond(60)) { assertEquals(policyID, getExplainManagedIndexMetaData(indexName).policyID) }
+        logger.info("before attempt move shards")
+        // Starts AttemptMoveShardsStep
+        updateManagedIndexConfigStartTime(managedIndexConfig)
+
+        // The action should be done after the no-op
+        waitFor(Instant.ofEpochSecond(60)) {
+            val metadata = getExplainManagedIndexMetaData(indexName)
+            assertEquals(
+                "Did not get the no-op due to no shard count change",
+                AttemptMoveShardsStep.NO_SHARD_COUNT_CHANGE_MESSAGE,
+                metadata.info?.get("message")
+            )
+            assertEquals(
+                "Was not on the last step after no-op due to no shard count change",
+                WaitForShrinkStep.name,
+                metadata.stepMetaData?.name
+            )
+        }
+    }
+
     @Suppress("UNCHECKED_CAST")
     fun `test shrink with replicas`() {
         val logger = LogManager.getLogger(::ShrinkActionIT)