add some unit tests for EmptyResponse

lib/src/main/java/com/nextcloud/android/sso/api/EmptyResponse.java

@@ -1,8 +1,10 @@
 package com.nextcloud.android.sso.api;
 
+import java.io.Serializable;
+
 /**
  * Use {@link EmptyResponse} as type for call which do not return a response body.
  * Replaced {@link Void} which was previously used for this scenario since <a href="https://github.com/nextcloud/Android-SingleSignOn/issues/541">Issue #541</a>
  */
-public final class EmptyResponse {
+public final class EmptyResponse implements Serializable {
 }

lib/src/test/java/com/nextcloud/android/sso/helper/TestOkhttp3Helper.java

@@ -0,0 +1,79 @@
+package com.nextcloud.android.sso.helper;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.lenient;
+
+import com.nextcloud.android.sso.aidl.NextcloudRequest;
+import com.nextcloud.android.sso.api.EmptyResponse;
+import com.nextcloud.android.sso.api.NextcloudAPI;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnit;
+import org.mockito.junit.MockitoRule;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.InputStream;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.util.ArrayList;
+
+import okhttp3.ResponseBody;
+
+
+public final class TestOkhttp3Helper {
+
+    private final String mApiEndpoint = "/index.php/apps/news/api/v1-2/";
+
+    @Mock
+    private NextcloudAPI nextcloudApiMock;
+
+    @Rule
+    public MockitoRule mockitoRule = MockitoJUnit.rule();
+
+    private InputStream objectToInputStream(Object obj) throws Exception {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        ObjectOutputStream oos = new ObjectOutputStream(baos);
+        oos.writeObject(obj);
+        oos.flush();
+        oos.close();
+        return new ByteArrayInputStream(baos.toByteArray());
+    }
+
+    @Test
+    public void testEmptyResponse() throws Exception {
+        EmptyResponse emptyResponse = new EmptyResponse();
+        InputStream is = objectToInputStream(emptyResponse);
+        lenient().when(nextcloudApiMock.performNetworkRequestV2(any())).thenReturn(new com.nextcloud.android.sso.api.Response(is, new ArrayList<>()));
+
+        final var request = new NextcloudRequest.Builder()
+                .setMethod("GET")
+                .setUrl(mApiEndpoint + "test")
+                .build();
+
+        ResponseBody rb = Okhttp3Helper.getResponseBodyFromRequestV2(nextcloudApiMock, request);
+        ObjectInputStream ois = new ObjectInputStream(rb.byteStream());
+        Object obj = ois.readObject();
+        assertEquals(EmptyResponse.class, obj.getClass());
+    }
+
+    @Test
+    public void testDataResponse() throws Exception {
+        String data = "some data";
+        InputStream is = objectToInputStream(data);
+        lenient().when(nextcloudApiMock.performNetworkRequestV2(any())).thenReturn(new com.nextcloud.android.sso.api.Response(is, new ArrayList<>()));
+
+        final var request = new NextcloudRequest.Builder()
+                .setMethod("GET")
+                .setUrl(mApiEndpoint + "test")
+                .build();
+
+        ResponseBody rb = Okhttp3Helper.getResponseBodyFromRequestV2(nextcloudApiMock, request);
+        ObjectInputStream ois = new ObjectInputStream(rb.byteStream());
+        Object obj = ois.readObject();
+        assertEquals(String.class, obj.getClass());
+    }
+}