*/
    public static char[] addAll(final char[] a, final char[] b) {
        if (a == null) {
            return b;
        }
        if (b == null) {
            return a;
        }
        if (a.length == 0) {
            return b;
        }
        if (b.length == 0) {
            return a;
        }
        final char[] array = (char[]) Array.newInstance(char.class, a.length + b.length);

    /**
     * Detail/bullet point icon.
     */
    DETAIL('•', "-"),

    /**
     * Action/arrow icon.
     */
    ACTION('→', ">");

    private final char unicodeChar;
    private final String asciiFallback;

    ConsoleIcon(char unicodeChar, String asciiFallback) {
        this.unicodeChar = unicodeChar;
        this.asciiFallback = asciiFallback;
    }

    /**

    // Exhaustively check all mappings (an int index avoids wrapping).
    for (int n = 0; n < replacementArray.length; n++) {
      char c = (char) n;
      String expected = map.get(c);
      if (expected == null) {
        assertThat(replacementArray[n]).isNull();
      } else {
        assertThat(new String(replacementArray[n])).isEqualTo(expected);
      }
    }
  }

            break;
        default:
            break;
        }
        return OptionalEntity.empty();
    }

    /**
     * Create a char mapping item.
     * @param form The create form.
     * @param hook The error hook.
     * @return An optional entity of a char mapping item.
     */
    protected OptionalEntity<CharMappingItem> createCharMappingItem(final CreateForm form, final VaErrorHook hook) {
        try {

        assertEquals(testStringTrue.length() + 1, unicodeStringTrue.buffer.length, "Buffer length should include zterm");
        for (int i = 0; i < testStringTrue.length(); i++) {
            assertEquals(testStringTrue.charAt(i), (char) unicodeStringTrue.buffer[i], "Character mismatch");
        }
        assertEquals(0, unicodeStringTrue.buffer[testStringTrue.length()], "Last character should be zero");

        // Test with a non-empty string and zterm = false

    @Override
    MessageBuilder append(char c);

    /**
     * Append content to the message buffer.
     *
     * @param value the content to append
     * @param offset the index of the first {@code char} to append
     * @param len the number of {@code char}s to append
     * @return the current builder
     */
    @Nonnull
    default MessageBuilder a(char[] value, int offset, int len) {

    assertThat(expected).hasMessageThat().isEqualTo(msg);
  }

  public void testBadArguments_plusforspace() {
    // space can be a safe char if plusForSpace is false
    PercentEscaper unused = new PercentEscaper(" ", false);

    // space cannot be a safe char is plusForSpace is true
    String msg = "plusForSpace cannot be specified when space is a 'safe' character";
    IllegalArgumentException expected =

  void tearDown() throws IOException;

  /** Factory for byte or char sources. */
  interface SourceFactory<S, T> extends SourceSinkFactory<S, T> {

    /** Creates a new source containing some or all of the given data. */
    S createSource(T data) throws IOException;
  }

  /** Factory for byte or char sinks. */
  interface SinkFactory<S, T> extends SourceSinkFactory<S, T> {

   *
   * @since 20.0 (varargs overload since 2.0)
   */
  public static void checkArgument(
      boolean expression, String errorMessageTemplate, char p1, char p2) {
    if (!expression) {
      throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
    }
  }

  /**

import java.io.FilterWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;
import org.jspecify.annotations.NullUnmarked;

/**
 * A char sink for testing that has configurable behavior.
 *
 * @author Colin Decker
 */
@NullUnmarked
public class TestCharSink extends CharSink implements TestStreamSupplier {

  private final TestByteSink byteSink;