Junit for the elastic search ParsedFilter

I am trying to cover Junit for Elasticsearch ParsedFilter.

Code:

	private void returnDeviceColumnValues(List<String> uniqueColumnValues, NativeSearchQuery searchQuery) {
	SearchHits<ESDashboardEntity> searchHits = operations.search(searchQuery, ESDashboardEntity.class);
	ElasticsearchAggregations aggregations = (ElasticsearchAggregations) searchHits.getAggregations();
	List<Aggregation> aggregationList = aggregations.aggregations().asList();
	aggregationList.forEach(agg -> {
		if (agg instanceof ParsedNested nestedAgg) {
			Aggregations subAggs = nestedAgg.getAggregations();
			ParsedFilter parseFilter = (ParsedFilter) subAggs.get(DashboardConstant.FILTER_AGG);
			ParsedStringTerms terms = parseFilter.getAggregations().get(DashboardConstant.UNIQUE_VALUES_AGG);
			for (Terms.Bucket bucket : terms.getBuckets()) {
				uniqueColumnValues.add(bucket.getKeyAsString());
			}
		} else if (agg instanceof Terms terms) {
			for (Terms.Bucket bucket : terms.getBuckets()) {
				uniqueColumnValues.add(bucket.getKeyAsString());
			}
		}

	});
}

Junit Code:

@Test
	void testReturnDeviceColumnValues_WithParsedFilter() throws IOException, MTValidationException {
		TypeReference<FilterColumnValuesDTO> typeReference = new TypeReference<>() {
		};
		FilterColumnValuesDTO deviceInput = BaseConverter.build("deviceFilterRequest.json", typeReference);

		NativeSearchQuery searchQuery = mock(NativeSearchQuery.class);
		TypeReference<ESDashboardEntity> dashboardTypeReference = new TypeReference<>() {
		};
		ESDashboardEntity deviceOutput = BaseConverter.build("ESDashboardEntity.json", dashboardTypeReference);
		String deviceInputString = mapper.writeValueAsString(deviceInput);
		ParsedNested nestedAgg = mock(ParsedNested.class);
		ParsedFilter parsedFilter = mock(ParsedFilter.class);
		ParsedStringTerms terms = mock(ParsedStringTerms.class);
		Aggregations subAggs = mock(Aggregations.class);
		when(aggregations.aggregations()).thenReturn(subAggs);
		when(nestedAgg.getAggregations()).thenReturn(subAggs);
		 when(subAggs.get(DashboardConstant.FILTER_AGG)).thenReturn(parsedFilter);
		Aggregations filterSubAggs = mock(Aggregations.class);
		when(parsedFilter.getAggregations()).thenReturn(filterSubAggs);
		
		List buckets = new ArrayList<>();
		Terms.Bucket bucket1 = mock(Terms.Bucket.class);
		when(bucket1.getKeyAsString()).thenReturn("value1");
		buckets.add(bucket1);
		when(terms.getBuckets()).thenReturn(buckets); // Executing the method
		List<ParsedNested> aggregationList = Collections.singletonList(nestedAgg);

		when(operations.search(Mockito.any(NativeSearchQuery.class), Mockito.eq(ESDashboardEntity.class)))
				.thenReturn(searchHits);
		List<SearchHit<ESDashboardEntity>> searchHit = new ArrayList<>();
		searchHit.add(new SearchHit("1", "1", null, 0, null, null, null, null, null, null, deviceOutput));
		when(searchHits.getSearchHits()).thenReturn(searchHit);
		when(searchHits.getTotalHits()).thenReturn(1l);
		when(searchHits.getMaxScore()).thenReturn(1.0f);
		when(searchHits.getAggregations()).thenReturn(aggregations);
		when(aggregations.aggregations()).thenReturn(new Aggregations((List<? extends Aggregation>) aggregationList));
		when(searchHits.getAggregations()).thenReturn(aggregations);

		String encodeToString = Base64.getEncoder().encodeToString(deviceInputString.getBytes());
		DeviceColumnFilterValuesDTO deviceColumnData = deviceService.getDeviceColumnData(encodeToString);

		assertNotNull(deviceColumnData);
	}

I am getting below exception. The subAgg is null


  

    java.lang.NullPointerException: Cannot invoke "java.util.List.size()" because "this.aggregations" is null
	at org.elasticsearch.search.aggregations.Aggregations.getAsMap(Aggregations.java:74)
	at org.elasticsearch.search.aggregations.Aggregations.asMap(Aggregations.java:66)
	at org.elasticsearch.search.aggregations.Aggregations.get(Aggregations.java:88)
	at com.mt.retail.dashboardservice.service.DeviceServiceTest.testReturnDeviceColumnValues_WithParsedFilter(DeviceServiceTest.java:374)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)