diff --git a/spring-5-reactive-client/pom.xml b/spring-5-reactive-client/pom.xml
index 6a0a2d6fe3..136f31b49e 100644
--- a/spring-5-reactive-client/pom.xml
+++ b/spring-5-reactive-client/pom.xml
@@ -133,7 +133,7 @@
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
                 <configuration>
-                    <mainClass>com.baeldung.reactive.Application</mainClass>
+                    <mainClass>com.baeldung.Spring5Application</mainClass>
                     <layout>JAR</layout>
                 </configuration>
             </plugin>
diff --git a/spring-5-reactive-client/src/main/java/com/baeldung/reactive/Application.java b/spring-5-reactive-client/src/main/java/com/baeldung/reactive/Application.java
deleted file mode 100644
index 65e497b519..0000000000
--- a/spring-5-reactive-client/src/main/java/com/baeldung/reactive/Application.java
+++ /dev/null
@@ -1,12 +0,0 @@
-package com.baeldung.reactive;
-
-import org.springframework.boot.SpringApplication;
-import org.springframework.boot.autoconfigure.SpringBootApplication;
-
-@SpringBootApplication
-public class Application {
-    public static void main(String[] args) {
-        SpringApplication.run(Application.class, args);
-    }
-}
-
diff --git a/spring-5-reactive-client/src/main/java/com/baeldung/reactive/controller/UploadController.java b/spring-5-reactive-client/src/main/java/com/baeldung/reactive/controller/UploadController.java
index 71cea35685..08d6ff55ef 100644
--- a/spring-5-reactive-client/src/main/java/com/baeldung/reactive/controller/UploadController.java
+++ b/spring-5-reactive-client/src/main/java/com/baeldung/reactive/controller/UploadController.java
@@ -27,21 +27,4 @@ public class UploadController {
     public Mono<HttpStatus> uploadMultipart(@RequestParam("file") final MultipartFile multipartFile) {
         return uploadService.uploadMultipart(multipartFile);
     }
-
-
-    /**
-     * Fake upload endpoint returning "OK" HttpStatus
-     * @return "OK" HttpStatus
-     */
-    @PostMapping(path = "/external/upload")
-    @ResponseBody
-    public HttpStatus externalUpload() {
-        return HttpStatus.OK;
-    }
-
-    @GetMapping("/trixi")
-    public String returnTrixi() {
-        return "Trixi";
-
-    }
 }
diff --git a/spring-5-reactive-client/src/main/java/com/baeldung/reactive/exception/ServiceException.java b/spring-5-reactive-client/src/main/java/com/baeldung/reactive/exception/ServiceException.java
new file mode 100644
index 0000000000..cd639ec1f9
--- /dev/null
+++ b/spring-5-reactive-client/src/main/java/com/baeldung/reactive/exception/ServiceException.java
@@ -0,0 +1,8 @@
+package com.baeldung.reactive.exception;
+
+public class ServiceException extends RuntimeException{
+
+    public ServiceException(String message) {
+        super(message);
+    }
+}
diff --git a/spring-5-reactive-client/src/main/java/com/baeldung/reactive/service/ReactiveUploadService.java b/spring-5-reactive-client/src/main/java/com/baeldung/reactive/service/ReactiveUploadService.java
index e31674282b..11409ce986 100644
--- a/spring-5-reactive-client/src/main/java/com/baeldung/reactive/service/ReactiveUploadService.java
+++ b/spring-5-reactive-client/src/main/java/com/baeldung/reactive/service/ReactiveUploadService.java
@@ -1,6 +1,7 @@
 package com.baeldung.reactive.service;
 
 
+import com.baeldung.reactive.exception.ServiceException;
 import org.springframework.core.io.Resource;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
@@ -20,50 +21,46 @@ public class ReactiveUploadService {
     private final WebClient webClient;
     private static final String EXTERNAL_UPLOAD_URL = "http://localhost:8080/external/upload";
 
-    public ReactiveUploadService() {
-        this.webClient = WebClient.create();
+    public ReactiveUploadService(final WebClient webClient) {
+        this.webClient = webClient;
     }
 
 
-    public Mono<HttpStatus> uploadPdf(final Resource resource){
+    public Mono<HttpStatus> uploadPdf(final Resource resource) {
 
         final URI url = UriComponentsBuilder.fromHttpUrl(EXTERNAL_UPLOAD_URL).build().toUri();
         Mono<HttpStatus> httpStatusMono = webClient.post()
-                .uri(url)
-                .contentType(MediaType.APPLICATION_PDF)
-                .body(BodyInserters.fromResource(resource))
-                .exchangeToMono(response -> {
-                    if (response.statusCode().equals(HttpStatus.OK)) {
-                        return response.bodyToMono(HttpStatus.class).thenReturn(response.statusCode());
-                    } else {
-                        System.out.println("Failed to upload pdf. " + response.statusCode());
-                    }
-                    return null;
-                });
+          .uri(url)
+          .contentType(MediaType.APPLICATION_PDF)
+          .body(BodyInserters.fromResource(resource))
+          .exchangeToMono(response -> {
+            if (response.statusCode().equals(HttpStatus.OK)) {
+              return response.bodyToMono(HttpStatus.class).thenReturn(response.statusCode());
+            } else {
+              throw new ServiceException("Error uploading file");
+            }
+          });
         return httpStatusMono;
     }
 
 
-    public Mono<HttpStatus> uploadMultipart(final MultipartFile multipartFile){
+    public Mono<HttpStatus> uploadMultipart(final MultipartFile multipartFile) {
         final URI url = UriComponentsBuilder.fromHttpUrl(EXTERNAL_UPLOAD_URL).build().toUri();
 
         final MultipartBodyBuilder builder = new MultipartBodyBuilder();
         builder.part("file", multipartFile.getResource());
 
         Mono<HttpStatus> httpStatusMono = webClient.post()
-                .uri(url)
-                .contentType(MediaType.MULTIPART_FORM_DATA)
-                .body(BodyInserters.fromMultipartData(builder.build()))
-                .exchangeToMono(response -> {
-                    if (response.statusCode().equals(HttpStatus.OK)) {
-                        return response.bodyToMono(HttpStatus.class).thenReturn(response.statusCode());
-                    } else {
-                        System.out.println("Failed to upload pdf. " + response.statusCode());
-                    }
-                    return null;
-                });
+          .uri(url)
+          .contentType(MediaType.MULTIPART_FORM_DATA)
+          .body(BodyInserters.fromMultipartData(builder.build()))
+          .exchangeToMono(response -> {
+            if (response.statusCode().equals(HttpStatus.OK)) {
+              return response.bodyToMono(HttpStatus.class).thenReturn(response.statusCode());
+            } else {
+                throw new ServiceException("Error uploading file");
+            }
+          });
         return httpStatusMono;
     }
-
-
 }
diff --git a/spring-5-reactive-client/src/main/resources/application.properties b/spring-5-reactive-client/src/main/resources/application.properties
index 7859537230..05033054b1 100644
--- a/spring-5-reactive-client/src/main/resources/application.properties
+++ b/spring-5-reactive-client/src/main/resources/application.properties
@@ -1,5 +1,5 @@
 logging.level.root=INFO
 
-server.port=8080
+server.port=8081
 
 logging.level.reactor.netty.http.client.HttpClient=DEBUG
\ No newline at end of file
diff --git a/spring-5-reactive-client/src/test/java/com/baeldung/reactive/service/ReactiveUploadServiceUnitTest.java b/spring-5-reactive-client/src/test/java/com/baeldung/reactive/service/ReactiveUploadServiceUnitTest.java
new file mode 100644
index 0000000000..0ca59848d7
--- /dev/null
+++ b/spring-5-reactive-client/src/test/java/com/baeldung/reactive/service/ReactiveUploadServiceUnitTest.java
@@ -0,0 +1,44 @@
+package com.baeldung.reactive.service;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.core.io.Resource;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.multipart.MultipartFile;
+import org.springframework.web.reactive.function.client.ClientResponse;
+import org.springframework.web.reactive.function.client.WebClient;
+import reactor.core.publisher.Mono;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class ReactiveUploadServiceUnitTest {
+
+    private static final String BASE_URL = "http://localhost:8080/external/upload";
+
+    final WebClient webClientMock = WebClient.builder().baseUrl(BASE_URL)
+            .exchangeFunction(clientRequest -> Mono.just(ClientResponse.create(HttpStatus.OK)
+               .header("content-type", "application/json")
+               .build()))
+            .build();
+
+    private final ReactiveUploadService tested = new ReactiveUploadService(webClientMock);
+
+    @Test
+    void givenAPdf_whenUploadingWithWebClient_thenOK() {
+        final Resource file = mock(Resource.class);
+        final Mono<HttpStatus> result = tested.uploadPdf(file);
+        final HttpStatus status = result.block();
+        assertThat(status).isEqualTo(HttpStatus.OK);
+    }
+
+    @Test
+    void givenAMultipartPdf_whenUploadingWithWebClient_thenOK() {
+        final Resource file = mock(Resource.class);
+        final MultipartFile multipartFile = mock(MultipartFile.class);
+        when(multipartFile.getResource()).thenReturn(file);
+        final Mono<HttpStatus> result = tested.uploadMultipart(multipartFile);
+        final HttpStatus status = result.block();
+        assertThat(status).isEqualTo(HttpStatus.OK);
+    }
+}
\ No newline at end of file