Controller
package com.bezkoder.springjwt.controllers; import com.bezkoder.springjwt.models.Product; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.http.HttpHeaders; import org.springframework.http.MediaType; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.reactive.function.client.WebClient; import org.springframework.web.util.UriComponentsBuilder; import reactor.core.publisher.Mono; import java.util.Arrays; import java.util.function.Consumer; @RestController public class ProductClientController { @Autowired WebClient webClient; @GetMapping("/catproducts") public String callSaveProductApi() { String response = null; Product product = new Product(); product.setId(1l); product.setName("kumar2"); product.setPrice(88); try { response = webClient.post() .uri(UriComponentsBuilder.fromUriString("http://localhost:8080/products").build().toString()) .headers(getHttpHeadersConsumer()).body(Mono.just(product), Product.class) .retrieve().bodyToMono(String.class).block(); } catch (Exception e) { System.out.println(e); } return response; } private Consumer<HttpHeaders> getHttpHeadersConsumer() { return httpHeaders -> { httpHeaders.setContentType(MediaType.APPLICATION_JSON); httpHeaders.setAccept(Arrays.asList(MediaType.APPLICATION_JSON)); }; } }Controller Test
package com.bezkoder.springjwt.controllers;import com.bezkoder.springjwt.models.Product;import org.junit.jupiter.api.Test;import org.junit.jupiter.api.extension.ExtendWith;import org.mockito.ArgumentMatchers;import org.mockito.InjectMocks;import org.mockito.Mock;import org.mockito.junit.jupiter.MockitoExtension;import org.springframework.web.reactive.function.client.WebClient;import reactor.core.publisher.Mono;import static org.mockito.ArgumentMatchers.any;import static org.mockito.ArgumentMatchers.anyString;import static org.mockito.Mockito.lenient;import static org.mockito.Mockito.when;@ExtendWith(MockitoExtension.class)public class ProductClientControllerTest { @InjectMocks ProductClientController productClientController; @Mock WebClient webClientMock; @Mock private WebClient.RequestBodyUriSpec requestBodyUriSpecMock; @Mock private WebClient.RequestBodySpec requestBodySpecMock; @Mock private WebClient.RequestHeadersUriSpec requestHeadersUriSpecMock; @Mock private WebClient.RequestHeadersSpec requestHeadersSpecMock; @Mock private WebClient.ResponseSpec responseSpecMock; @Test void callSaveProductApi(){ Product product = new Product(); product.setId(1l); product.setName("kumar2"); product.setPrice(88); when(webClientMock.post()) .thenReturn(requestBodyUriSpecMock); when(requestBodyUriSpecMock.uri(anyString())) .thenReturn(requestBodySpecMock); when(requestBodySpecMock.body(Mono.just(product), Product.class)) .thenReturn(requestHeadersSpecMock); when(requestBodyUriSpecMock.headers(any())).thenReturn(requestBodySpecMock); when(requestHeadersSpecMock.retrieve()) .thenReturn(responseSpecMock); when(responseSpecMock.bodyToMono(ArgumentMatchers.<Class<String>>notNull())) .thenReturn(Mono.just("success")); String s = productClientController.callSaveProductApi(); }}Getting this exception
java.lang.NullPointerException: Cannot invoke"org.springframework.web.reactive.function.client.WebClient$RequestBodySpec.body(org.reactivestreams.Publisher,java.lang.Class)" because the return value of"org.springframework.web.reactive.function.client.WebClient$RequestBodySpec.headers(java.util.function.Consumer)"is null