static final String ERROR_ADDED_SELF_LOOP = "Should not be allowed to add a self-loop edge.";

  /** Creates and returns an instance of the graph to be tested. */
  abstract Graph<Integer> createGraph();

  /**
   * A proxy method that adds the node {@code n} to the graph being tested. In case of Immutable
   * graph implementations, this method should replace {@link #graph} with a new graph that includes
   * this node.
   */

    assertEquals(2, copy.size());
    assertSame(copy, copy.iterator().next().member);
  }

  /*
   * The behavior of toString() and iteration is tested by LinkedHashMultiset,
   * which shares a lot of code with HashMultiset and has deterministic
   * iteration order.
   */

 * <p>
 * Beans injected into Mojo parameters are prepared by <a href="https://www.eclipse.org/sisu/">Sisu</a> JSR330-based
 * container: this annotation is only effective on fields of the Mojo class itself, nested bean injection
 * requires Sisu or JSR330 annotations.
 *
 * @since 4.0.0
 */
@Experimental
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD})
@Inherited

        assertTrue(duration < 1000, "Creating and using 10000 EmptyIterators should be fast (took " + duration + "ms)");
    }

    @Test
    @DisplayName("EmptyIterator should work correctly in nested iteration")
    void testNestedIteration() {
        // When & Then
        assertDoesNotThrow(() -> {
            int outerCount = 0;
            while (emptyIterator.hasNext()) {

     * @param lineNumber The one-based index of the line containing the error or {@code -1} if unknown.
     * @param columnNumber The one-based index of the column containing the error or {@code -1} if unknown.
     * @param cause The nested cause of this error, may be {@code null}.
     */
    public MetadataParseException(String message, int lineNumber, int columnNumber, Throwable cause) {
        super(message);
        initCause(cause);

        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**.

        MavenSession oldSession = legacySupport.getSession();

        scope.enter();

        try {
            scope.seed(MavenProject.class, project);
            scope.seed(MojoExecution.class, mojoExecution);
            scope.seed(
                    org.apache.maven.api.plugin.Log.class,
                    new DefaultLog(LoggerFactory.getLogger(

 *       have, of returning a new, independent iterator
 * </ul>
 *
 * <p>Because of this situation, any public method accepting an iterable should invoke the {@code
 * iterator} method only once, and should be tested using this class. Exceptions to this rule should
 * be clearly documented.
 *
 * <p>Note that although your APIs should be liberal in what they accept, your methods which

     * @param lineNumber The one-based index of the line containing the error or {@code -1} if unknown.
     * @param columnNumber The one-based index of the column containing the error or {@code -1} if unknown.
     * @param cause The nested cause of this error, may be {@code null}.
     */
    public ToolchainsParseException(String message, int lineNumber, int columnNumber, Throwable cause) {
        super(message);
        initCause(cause);