Class CustomClientTest

form/src/test/java/feign/form/CustomClientTest.java:38–83

import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest(webEnvironment = DEFINED_PORT, classes = Server.class)
class CustomClientTest {

  private static CustomClient API;

  @TempDir static Path logDir;

  @BeforeAll
  static void configureClient() {
    var encoder = new FormEncoder(new JacksonEncoder());
    var processor = (MultipartFormContentProcessor) encoder.getContentProcessor(MULTIPART);
    processor.addFirstWriter(new CustomByteArrayWriter());

    var logFile = logDir.resolve("log.txt").toString();

    API =
        Feign.builder()
            .encoder(encoder)
            .logger(new JavaLogger(CustomClientTest.class).appendToFile(logFile))
            .logLevel(FULL)
            .target(CustomClient.class, "http://localhost:8080");
  }

  @Test
  void test() {
    assertThat(API.uploadByteArray(new byte[0])).isNotNull().isEqualTo("popa.txt");
  }

  private static final class CustomByteArrayWriter extends ByteArrayWriter {

    @Override
    protected void write(Output output, String key, Object value) throws EncodeException {
      writeFileMetadata(output, key, "popa.txt", null);

      var bytes = (byte[]) value;
      output.write(bytes);
    }
  }

  interface CustomClient {

    @RequestLine("POST /upload/byte_array")
    @Headers("Content-Type: multipart/form-data")
    String uploadByteArray(@Param("file") byte[] bytes);
  }
}