}
    }

    try {
      Range<C> span = rangeSet.span();
      assertEquals(expectedSpan, span);
    } catch (NoSuchElementException e) {
      assertThat(expectedSpan).isNull();
    }

    // test that asDescendingSetOfRanges is the reverse of asRanges
    assertEquals(Lists.reverse(asRanges), ImmutableList.copyOf(rangeSet.asDescendingSetOfRanges()));
  }

import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.ArgumentMatchers.isNull;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.verifyNoMoreInteractions;
import static org.mockito.Mockito.when;

import java.lang.reflect.Method;

import assertk.assertions.isEqualTo
import assertk.assertions.isGreaterThan
import assertk.assertions.isGreaterThanOrEqualTo
import assertk.assertions.isNotEqualTo
import assertk.assertions.isNotNull
import assertk.assertions.isNull
import assertk.assertions.isTrue
import java.io.BufferedReader
import java.io.Closeable
import java.io.IOException
import java.io.InputStreamReader
import java.net.ConnectException
import java.net.HttpURLConnection

    assertThat(Strings.nullToEmpty("")).isEqualTo("");
    assertThat(Strings.nullToEmpty("a")).isEqualTo("a");
  }

  public void testEmptyToNull() {
    assertThat(Strings.emptyToNull(null)).isNull();
    assertThat(Strings.emptyToNull("")).isNull();
    assertThat(Strings.emptyToNull("a")).isEqualTo("a");
  }

  public void testIsNullOrEmpty() {
    assertTrue(Strings.isNullOrEmpty(null));
    assertTrue(Strings.isNullOrEmpty(""));

@GwtCompatible
@NullUnmarked
public class CallablesTest extends TestCase {

  @J2ktIncompatible // TODO(b/324550390): Enable
  public void testReturning() throws Exception {
    assertThat(Callables.returning(null).call()).isNull();

    Object value = new Object();
    Callable<Object> callable = Callables.returning(value);
    assertThat(callable.call()).isEqualTo(value);
    // Expect the same value on subsequent calls

@GwtCompatible
@NullUnmarked
public class CallablesTest extends TestCase {

  @J2ktIncompatible // TODO(b/324550390): Enable
  public void testReturning() throws Exception {
    assertThat(Callables.returning(null).call()).isNull();

    Object value = new Object();
    Callable<Object> callable = Callables.returning(value);
    assertThat(callable.call()).isEqualTo(value);
    // Expect the same value on subsequent calls

        ImmutableSortedSet.copyOf(new String[] {"e", "e", "f", "b", "i", "d", "c", "k"});
    assertThat(set.floor("a")).isNull();
  }

  public void testCeiling_emptySet() {
    ImmutableSortedSet<String> set = ImmutableSortedSet.copyOf(new String[] {});
    assertThat(set.ceiling("f")).isNull();
  }

  public void testCeiling_elementPresent() {
    ImmutableSortedSet<String> set =

    String string = source.read();
    assertExpectedString(string);
  }

  public void testReadFirstLine() throws IOException {
    if (expectedLines.isEmpty()) {
      assertThat(source.readFirstLine()).isNull();
    } else {
      assertThat(source.readFirstLine()).isEqualTo(expectedLines.get(0));
    }
  }

  public void testReadLines_toList() throws IOException {
    assertExpectedLines(source.readLines());

    assertThat(TypeToken.of(Object.class).getComponentType()).isNull();
    assertThat(TypeToken.of(void.class).getComponentType()).isNull();
  }

  public <T> void testGetComponentType_genericArrayClasses() {
    assertThat(TypeToken.of(new TypeCapture<T>() {}.capture()).getComponentType()).isNull();
    assertEquals(
        TypeToken.of(new TypeCapture<T>() {}.capture()),

                actualOccupiedDepth.set(monitor.getOccupiedDepth());
              } catch (Throwable t) {
                thrown.set(t);
              }
            }));
    assertThat(thrown.get()).isNull();
    assertEquals(expectedIsOccupied, actualIsOccupied.get());
    assertEquals(expectedIsOccupiedByCurrentThread, actualIsOccupiedByCurrentThread.get());
    assertEquals(expectedOccupiedDepth, actualOccupiedDepth.get());