package ch.qos.logback.classic.spi;
   
   import java.io.PrintStream;
   
   import org.junit.jupiter.api.AfterEach;
   import org.junit.jupiter.api.BeforeEach;
   import org.junit.jupiter.api.Test;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
  import org.slf4j.LoggerFactoryFriend;
  
  import ch.qos.logback.classic.testUtil.StringPrintStream;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  import static org.slf4j.helpers.Reporter.SLF4J_INTERNAL_VERBOSITY_KEY;
  
  public class InvocationTest {
  
      private final PrintStream oldErr = System.err;
      final String loggerName = this.getClass().getName();
      StringPrintStream sps = new StringPrintStream(oldErr, true);
  
      String CONNECTED_WITH_MESSAGE = "SLF4J(D): Connected with provider of type [ch.qos.logback.classic.spi.LogbackServiceProvider]";
  
      @BeforeEach
      public void setUp() throws Exception {
          System.setProperty(SLF4J_INTERNAL_VERBOSITY_KEY, "debug");
          System.setErr(sps);
      }
  
      @AfterEach
      public void tearDown() throws Exception {
          LoggerFactoryFriend.reset();
          System.setErr(oldErr);
          System.clearProperty(SLF4J_INTERNAL_VERBOSITY_KEY);
      }
  
      // https://jira.qos.ch/browse/LOGBACK-1568 would have been prevented
      // had this silly test existed.
      @Test
      public void smoke() {
          Logger logger = LoggerFactory.getLogger(this.getClass());
          logger.debug("Hello world.");
  
          assertEquals(1, sps.stringList.size());
          assertEquals(CONNECTED_WITH_MESSAGE, sps.stringList.get(0));
  
      }
  
  }