underlying.put("a", 1);
    Map<String, String> map = transformValues(underlying, Functions.toStringFunction());
    assertThat(map.remove("a")).isEqualTo("1");
    assertThat(map.remove("b")).isNull();
  }

  public void testTransformEqualityOfMapsWithNullValues() {
    Map<String, @Nullable String> underlying = new HashMap<>();
    underlying.put("a", null);
    underlying.put("b", "");

    underlying.put("a", 1);
    Map<String, String> map = transformValues(underlying, Functions.toStringFunction());
    assertThat(map.remove("a")).isEqualTo("1");
    assertThat(map.remove("b")).isNull();
  }

  public void testTransformEqualityOfMapsWithNullValues() {
    Map<String, @Nullable String> underlying = new HashMap<>();
    underlying.put("a", null);
    underlying.put("b", "");

import assertk.assertions.contains
import assertk.assertions.hasMessage
import assertk.assertions.isCloseTo
import assertk.assertions.isEqualTo
import assertk.assertions.isFalse
import assertk.assertions.isNull
import assertk.assertions.isTrue
import assertk.fail
import java.io.IOException
import java.net.HttpURLConnection
import java.net.SocketTimeoutException
import java.time.Duration
import java.util.Arrays

  }

  public void testGetOnlyElement_withDefault_empty_null() {
    Iterator<String> iterator = emptyIterator();
    assertThat(Iterators.<@Nullable String>getOnlyElement(iterator, null)).isNull();
  }

  public void testGetOnlyElement_withDefault_two() {
    Iterator<String> iterator = asList("foo", "bar").iterator();
    IllegalArgumentException expected =

      assertThat(urls.get(0).getAuthority()).isNull();
      assertThat(urls.get(0).getPath()).endsWith("/relative/path/to/some.jar");

      assertThat(urls.get(1)).isEqualTo(new URL("file:///absolute/path/to/some.jar"));

      assertThat(urls.get(2).getProtocol()).isEqualTo("file");
      assertThat(urls.get(2).getAuthority()).isNull();

  }

  public void testGetOnlyElement_withDefault_empty_null() {
    Iterator<String> iterator = emptyIterator();
    assertThat(Iterators.<@Nullable String>getOnlyElement(iterator, null)).isNull();
  }

  public void testGetOnlyElement_withDefault_two() {
    Iterator<String> iterator = asList("foo", "bar").iterator();
    IllegalArgumentException expected =

      }
    } catch (Throwable caught) {
      assertThat(caught).isInstanceOf(IOException.class);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());
    assertThat(c3).isNull();

    assertTrue(suppressor.suppressions.isEmpty());
  }

  public void testExceptionThrown_whileClosingLastCloseable() throws IOException {
    Closer closer = new Closer(suppressor);

  @Override
  protected final void tearDown() {
    tearDownStack.runTearDown();
    assertWithMessage("exceptions should not be propagated to uncaught exception handlers")
        .that(thrownByExecutionThread)
        .isNull();
  }

  public void testServiceStartStop() throws Exception {
    WaitOnRunService service = new WaitOnRunService();
    assertFalse(service.startUpCalled);

    service.startAsync().awaitRunning();

  @Override
  protected final void tearDown() {
    tearDownStack.runTearDown();
    assertWithMessage("exceptions should not be propagated to uncaught exception handlers")
        .that(thrownByExecutionThread)
        .isNull();
  }

  public void testServiceStartStop() throws Exception {
    WaitOnRunService service = new WaitOnRunService();
    assertFalse(service.startUpCalled);

    service.startAsync().awaitRunning();

  }

  /** Checks that #drain() invocations behave correctly for a drained (empty) queue. */
  private void assertDrained(BlockingQueue<Object> q) {
    assertThat(q.peek()).isNull();
    assertInterruptibleDrained(q);
    assertUninterruptibleDrained(q);
  }

  private void assertInterruptibleDrained(BlockingQueue<Object> q) {
    // nothing to drain, thus this should wait doing nothing