Implement real async COS image upload

src/test/java/com/openisle/service/CosImageUploaderTest.java

@@ -1,14 +1,21 @@
 package com.openisle.service;
 
+import com.qcloud.cos.COSClient;
+import com.qcloud.cos.model.PutObjectRequest;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
 
 class CosImageUploaderTest {
     @Test
     void uploadReturnsUrl() {
-        CosImageUploader uploader = new CosImageUploader("http://cos.example.com");
-        String url = uploader.upload("data".getBytes(), "img.png");
+        COSClient client = mock(COSClient.class);
+        CosImageUploader uploader = new CosImageUploader(client, "bucket", "http://cos.example.com");
+
+        String url = uploader.upload("data".getBytes(), "img.png").join();
+
+        verify(client).putObject(any(PutObjectRequest.class));
         assertEquals("http://cos.example.com/img.png", url);
     }
 }