code: /*
   * Copyright (c) 2022 Airbyte, Inc., all rights reserved.
   */
  
  package io.airbyte.integrations.source.relationaldb;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.mockito.Mockito.mock;
  import static org.mockito.Mockito.spy;
  
  import com.fasterxml.jackson.databind.JsonNode;
  import io.airbyte.commons.features.EnvVariableFeatureFlags;
  import io.airbyte.commons.json.Jsons;
  import io.airbyte.commons.resources.MoreResources;
  import io.airbyte.protocol.models.AirbyteStateMessage;
  import io.airbyte.protocol.models.AirbyteStateMessage.AirbyteStateType;
  import java.io.IOException;
  import java.lang.reflect.Field;
  import java.util.List;
  import java.util.Map;
  import org.junit.jupiter.api.Test;
  
  /**
   * Test suite for the {@link AbstractDbSource} class.
   */
  public class AbstractDbSourceTest {
  
    @Test
    void testDeserializationOfLegacyState() throws IOException {
      final AbstractDbSource dbSource = spy(AbstractDbSource.class);
      final JsonNode config = mock(JsonNode.class);
  
      final String legacyStateJson = MoreResources.readResource("states/legacy.json");
      final JsonNode legacyState = Jsons.deserialize(legacyStateJson);
  
      final List<AirbyteStateMessage> result = dbSource.deserializeInitialState(legacyState, config);
      assertEquals(1, result.size());
      assertEquals(AirbyteStateType.LEGACY, result.get(0).getType());
    }
  
    @Test
    void testDeserializationOfGlobalState() throws IOException {
      setEnv(EnvVariableFeatureFlags.USE_STREAM_CAPABLE_STATE, "true");
      final AbstractDbSource dbSource = spy(AbstractDbSource.class);
      final JsonNode config = mock(JsonNode.class);
  
      final String globalStateJson = MoreResources.readResource("states/global.json");
      final JsonNode globalState = Jsons.deserialize(globalStateJson);
  
      final List<AirbyteStateMessage> result = dbSource.deserializeInitialState(globalState, config);
      assertEquals(1, result.size());
      assertEquals(AirbyteStateType.GLOBAL, result.get(0).getType());
    }
  
    @Test
    void testDeserializationOfStreamState() throws IOException {
      setEnv(EnvVariableFeatureFlags.USE_STREAM_CAPABLE_STATE, "true");
      final AbstractDbSource dbSource = spy(AbstractDbSource.class);
      final JsonNode config = mock(JsonNode.class);
  
      final String streamStateJson = MoreResources.readResource("states/per_stream.json");
      final JsonNode streamState = Jsons.deserialize(streamStateJson);
  
      final List<AirbyteStateMessage> result = dbSource.deserializeInitialState(streamState, config);
      assertEquals(2, result.size());
      assertEquals(AirbyteStateType.STREAM, result.get(0).getType());
    }
  
    @Test
    void testDeserializationOfNullState() throws IOException {
      final AbstractDbSource dbSource = spy(AbstractDbSource.class);
      final JsonNode config = mock(JsonNode.class);
  
      final List<AirbyteStateMessage> result = dbSource.deserializeInitialState(null, config);
      assertEquals(1, result.size());
      assertEquals(dbSource.getSupportedStateType(config), result.get(0).getType());
    }
  
    public static void setEnv(final String key, final String value) {
      try {
        final Map<String, String> env = System.getenv();
        final Class<?> cl = env.getClass();
        final Field field = cl.getDeclaredField("m");
        field.setAccessible(true);
        final Map<String, String> writableEnv = (Map<String, String>) field.get(env);
        writableEnv.put(key, value);
      } catch (final Exception e) {
        throw new IllegalStateException("Failed to set environment variable", e);
      }
    }
  
  }
  