add first Feign Client with registrate method and test

fh.fd.ci.client/build.gradle

@@ -7,6 +7,12 @@ mainClassName = 'de.fd.fh.ClientApp'
 
 dependencies {
     implementation project(':fh.fd.ci.shared')
+
+    implementation 'io.github.openfeign:feign-okhttp:11.0'
+    implementation 'io.github.openfeign:feign-gson:11.0'
+    implementation 'io.github.openfeign:feign-slf4j:11.0'
+
+    testImplementation 'io.github.openfeign:feign-mock:11.0'
 }
 
 javafx {

fh.fd.ci.client/src/main/java/de/fd/fh/network/AccessClient.java

@@ -0,0 +1,11 @@
+package de.fd.fh.network;
+
+import de.fd.fh.shared.network.messages.RegistrateRequest;
+import feign.RequestLine;
+import feign.Response;
+
+public interface AccessClient
+{
+    @RequestLine("POST /accounts/registrate")
+    Response registrate(RegistrateRequest request);
+}

fh.fd.ci.client/src/main/java/de/fd/fh/network/FeignClients.java

@@ -0,0 +1,29 @@
+package de.fd.fh.network;
+
+import feign.Feign;
+import feign.gson.GsonDecoder;
+import feign.gson.GsonEncoder;
+import feign.okhttp.OkHttpClient;
+import lombok.Getter;
+
+@Getter
+public class FeignClients
+{
+    private static final String BASE_URL = "http://localhost:4567";
+
+    private AccessClient accessClient;
+
+    public FeignClients()
+    {
+        accessClient = buildClient(AccessClient.class);
+    }
+
+    <T> T buildClient(final Class<T> client)
+    {
+        return Feign.builder()
+                .client(new OkHttpClient())
+                .encoder(new GsonEncoder())
+                .decoder(new GsonDecoder())
+                .target(client, BASE_URL);
+    }
+}

fh.fd.ci.client/src/test/java/de/fd/fh/network/AccessClientTest.java

@@ -0,0 +1,46 @@
+package de.fd.fh.network;
+
+import de.fd.fh.shared.network.messages.RegistrateRequest;
+import feign.Feign;
+import feign.Response;
+import feign.gson.GsonDecoder;
+import feign.gson.GsonEncoder;
+import feign.mock.HttpMethod;
+import feign.mock.MockClient;
+import feign.mock.MockTarget;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class AccessClientTest
+{
+    private AccessClient client;
+    private MockClient mockClient;
+
+    @BeforeEach
+    void before()
+    {
+        mockClient = new MockClient();
+
+        client = Feign.builder()
+                .decoder(new GsonDecoder())
+                .encoder(new GsonEncoder())
+                .client(mockClient)
+                .target(new MockTarget<>(AccessClient.class));
+    }
+
+    @Test
+    void testRegistrate()
+    {
+        mockClient.ok(HttpMethod.POST, "/accounts/registrate");
+
+        final RegistrateRequest request = RegistrateRequest.of("TestName", "TestPassword");
+
+        final Response result = client.registrate(request);
+
+        assertEquals(200, result.status(), "Should return status code 200.");
+
+        mockClient.verifyStatus();
+    }
+}