Spring WebFlux project that connects to ElasticSearch Unit Testing - unit-testing

Question

I am currently working on a Spring WebFlux project that connects to ElasticSearch. I have a Rest Service that in turn calls a method in the Service Layer that connects to the ES. I am having trouble writing UnitTests for my Service Layer. Any help would be appreciated as this is the first time I am working with Reactive Programming. Below are the code snippets for my Controller and Service methods.
Controller Code :
#GetMapping(path = "/api/apis/services/{id}", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
Flux<ClassA> serviceApis(#PathVariable final String serviceKey) {
return apiService.getDataForService(serviceKey);
}
Service Layer :
#PreAuthorize("isFullyAuthenticated()")
public Flux<ClassA> getDataForService(
final String id) {
IdentityToken token = GSLSecurityContext.getCurrentUserIdentityToken();
if (token == null) {
return Flux.error(new Exception("No token found"));
}
String securityQueryJson = getSecurityShould(token);
String queryToRun = QUERY
.replace("XXX_SIZE_XXX", config.getValueAsString("scroll.size"))
.replace("XXX_SECURITY_SHOULD_XXX", securityQueryJson)
.replace("XXX_SERVICE_KEY_XXX", id);
WebClient client = ClientUtil.getDataLakeWebClient(config);
Flux<ClassA> response = getData(client, queryToRun);
return response;
}
The getData code is as below :
protected Flux<ClassA> getData(
final WebClient client,
final String queryToRun) {
String scrollTimeoutQuery = "?scroll=" + config.getValueAsString("scroll.timeout");
long timeout = config.getValueAsLong("query.timout");
return Flux.generate(
() -> null,
(scrollId, sink) -> {
ClassAWrapper lastWrapper = null;
if (scrollId == null) {
Mono<ClassAWrapper> wrapper = client.post()
.uri(getSearchURI() + scrollTimeoutQuery)
.body(BodyInserters.fromObject(queryToRun)).retrieve()
.bodyToMono(ClassAWrapper.class)
.onErrorMap(original -> new Exception("Unable to retrieve from elastic search for query " + queryToRun, original))
.log();
try {
lastWrapper = wrapper.block(Duration.ofSeconds(timeout));
} catch (IllegalStateException ex) {
LOG.error("Timedout after " + timeout + " seconds while getting data from elastic search for query " + queryToRun);
lastWrapper = null;
} catch (Exception ex) {
LOG.error("Error in getting message details",ex);
lastWrapper = null;
}
} else {
String scrollQuery = "{\"scroll\" : \"" + config.getValueAsString("scroll.timeout") + "\", \"scroll_id\" : \"" + scrollId + "\"}";
Mono<ClassAWrapper> wrapper = client.post()
.uri("_search/scroll")
.body(BodyInserters.fromObject(scrollQuery)).retrieve()
.bodyToMono(ClassAWrapper.class)
.onErrorMap(original -> new Exception("Unable to retrieve next page of data from elastic search", original))
.log();
try {
lastWrapper = wrapper.block(Duration.ofSeconds(timeout));
} catch (IllegalStateException ex) {
LOG.error("Timeout after " + timeout + " seconds while getting data from elastic search for query " + queryToRun);
lastWrapper = null;
} catch (Exception ex) {
LOG.error("Error in getting message details",ex);
lastWrapper = null;
}
}
if (lastWrapper == null || lastWrapper.getResult() == null || lastWrapper.getResult().getDetails().isEmpty()) {
sink.next(new ClassA());
sink.complete();
return null;
}
sink.next(lastWrapper.getResult());
return lastWrapper.getScrollId();
}
);
}
Here, queryToRun is the ES query to be executed. config is the configuration. I need to test the method "getDataForService()".