assertEquals(longMessage, exception.getMessage());
        assertNull(exception.getCause());
    }

    public void test_constructor_withNestedCause() {
        // Test constructor with nested exception causes
        Exception rootCause = new IllegalStateException("Root cause");
        Exception middleCause = new RuntimeException("Middle cause", rootCause);
        String message = "Top level dictionary error";

        mockPipeIn.lock = new Object();

        byte[] buffer = new byte[10];
        int bufferIndex = 0;
        int len = 10;

        // Call the method to be tested
        int result = response.readDataWireFormat(buffer, bufferIndex, len);

        // Verify the result
        assertEquals(len, result, "readDataWireFormat should return the length of data read.");

Just functions that look the same as the *path operation functions*.

But still, it is very powerful, and allows you to declare arbitrarily deeply nested dependency "graphs" (trees).

/// tip

All this might not seem as useful with these simple examples.

But you will see how useful it is in the chapters about **security**.

        // getMessage() may return null when constructed with null
        // This is expected behavior for exceptions with null cause
    }

    public void test_nestedCause() {
        // Test with nested exceptions
        RuntimeException rootCause = new RuntimeException("Root cause");
        ParseException parseException = new ParseException("Parse error");
        parseException.initCause(rootCause);

        assertEquals(0, SessionSetupHandler.class.getDeclaredFields().length, "No fields expected");
        assertEquals(0, SessionSetupHandler.class.getDeclaredClasses().length, "No nested types expected");
    }

    @ParameterizedTest(name = "Implementation is instance: {0}")
    @MethodSource("implementations")
    @DisplayName("Happy path: can create implementations and use type checks")

        assertEquals(message, exception.getMessage());
        assertNull(exception.getCause());
    }

    public void test_constructor_withNestedCause() {
        // Test constructor with nested exceptions
        Throwable rootCause = new IllegalStateException("Root cause");
        Throwable intermediateCause = new RuntimeException("Intermediate cause", rootCause);
        String message = "Top level error";

import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;

/**
 * Tests for {@link FluentFuture}. The tests cover only the basics for the API. The actual logic is
 * tested in {@link FuturesTest}.
 */
@NullMarked
@GwtCompatible
public class FluentFutureTest extends TestCase {
  @SuppressWarnings({"deprecation", "InlineMeInliner"}) // test of a deprecated method

import java.lang.reflect.Field;
import java.net.Socket;
import java.util.concurrent.atomic.AtomicLong;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.Mock;
import org.mockito.junit.jupiter.MockitoExtension;
import org.mockito.junit.jupiter.MockitoSettings;

        return map.isEmpty();
    }

    /**
     * Returns true if this set contains the specified element.
     *
     * @param o
     *            element whose presence in this set is to be tested.
     * @return true if this set contains the specified element.
     */
    @Override
    public boolean contains(final Object o) {
        return map.containsKey(o);
    }

    /**

        assertEquals(this.getClass().getName(), firstElement.getClassName());
        assertEquals("test_stackTracePresent", firstElement.getMethodName());
    }

    public void test_nestedExceptionChain() {
        // Test nested exception chain
        Throwable rootCause = new IllegalArgumentException("Root cause");
        Throwable middleCause = new IllegalStateException("Middle cause", rootCause);