code: /*
   * Copyright (c) 2022 Airbyte, Inc., all rights reserved.
   */
  
  package io.airbyte.db.jdbc.streaming;
  
  import static org.junit.jupiter.api.Assertions.*;
  
  import org.junit.jupiter.api.Test;
  
  class TwoStageSizeEstimatorTest {
  
    @Test
    void testDelegationSwitch() {
      final TwoStageSizeEstimator sizeEstimator = TwoStageSizeEstimator.getInstance();
      for (int i = 0; i < FetchSizeConstants.INITIAL_SAMPLE_SIZE; ++i) {
        sizeEstimator.accept("1");
        assertTrue(sizeEstimator.getDelegate() instanceof InitialSizeEstimator);
      }
      // delegation is changed after initial sampling
      for (int i = 0; i < 3; ++i) {
        sizeEstimator.accept("1");
        assertTrue(sizeEstimator.getDelegate() instanceof SamplingSizeEstimator);
      }
    }
  
    @Test
    void testGetTargetBufferByteSize() {
      assertEquals(FetchSizeConstants.MIN_BUFFER_BYTE_SIZE,
          TwoStageSizeEstimator.getTargetBufferByteSize(null));
      assertEquals(FetchSizeConstants.MIN_BUFFER_BYTE_SIZE,
          TwoStageSizeEstimator.getTargetBufferByteSize(Long.MAX_VALUE));
      assertEquals(FetchSizeConstants.MIN_BUFFER_BYTE_SIZE,
          TwoStageSizeEstimator.getTargetBufferByteSize(FetchSizeConstants.MIN_BUFFER_BYTE_SIZE - 10L));
      assertEquals(FetchSizeConstants.MAX_BUFFER_BYTE_SIZE,
          TwoStageSizeEstimator.getTargetBufferByteSize(
              Math.round(FetchSizeConstants.MAX_BUFFER_BYTE_SIZE / FetchSizeConstants.TARGET_BUFFER_SIZE_RATIO + 10L)));
    }
  
  }
  