public void testNullCloseable() throws IOException {
    Closer closer = Closer.create();
    closer.register(null);
    closer.close();
  }

  /**
   * Asserts that an exception was thrown when trying to close each of the given throwables and that
   * each such exception was suppressed because of the given thrown exception.
   */
  private void assertSuppressed(Suppression... expected) {

    @Override
    public boolean equals(@Nullable Object object) {
      // Cannot use key and value equivalence
      if (object instanceof Entry) {
        Entry<?, ?> that = (Entry<?, ?>) object;
        return key.equals(that.getKey()) && value.equals(that.getValue());
      }
      return false;
    }

    @Override
    public int hashCode() {
      // Cannot use key and value equivalence

        @Override
        public Object[] toArray() {
          /*
           * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it
           * can be used with collections that may contain null. This collection is a collection of
           * non-null Entry objects (Entry objects that might contain null values but are not
           * themselves null), so we can treat it as a plain `Object[]`.
           */

  // Double#doubleToRawLongBits(double)} spec.
  static final long SIGN_MASK = 0x8000000000000000L;

  static final int SIGNIFICAND_BITS = 52;

  static final int EXPONENT_BIAS = 1023;

  /** The implicit 1 bit that is omitted in significands of normal doubles. */
  static final long IMPLICIT_BIT = SIGNIFICAND_MASK + 1;

  static long getSignificand(double d) {
    checkArgument(isFinite(d), "not a normal value");

// fitsInBase256 reports whether x can be encoded into n bytes using base-256
// encoding. Unlike octal encoding, base-256 encoding does not require that the
// string ends with a NUL character. Thus, all n bytes are available for output.
//
// If operating in binary mode, this assumes strict GNU binary mode; which means
// that the first byte can only be either 0x80 or 0xff. Thus, the first byte is
// equivalent to the sign bit in two's complement form.

        assertWithMessage("roundToDouble(" + input + ", " + mode + ")")
            .that(BigDecimalMath.roundToDouble(input, mode))
            .isEqualTo(expectation);
      }

      if (!expectedValues.containsKey(UNNECESSARY)) {
        assertWithMessage("Expected roundUnnecessaryShouldThrow call")
            .that(unnecessaryShouldThrow)
            .isTrue();
        assertThrows(

import java.util.concurrent.TimeoutException;
import junit.framework.AssertionFailedError;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/** Replacements for JUnit's {@code assertThrows} that work under GWT/J2CL. */
@GwtCompatible
@NullMarked
final class ReflectionFreeAssertThrows {
  interface ThrowingRunnable {
    void run() throws Throwable;
  }

  interface ThrowingSupplier {

import java.util.concurrent.TimeoutException;
import junit.framework.AssertionFailedError;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/** Replacements for JUnit's {@code assertThrows} that work under GWT/J2CL. */
@GwtCompatible
@NullMarked
final class ReflectionFreeAssertThrows {
  interface ThrowingRunnable {
    void run() throws Throwable;
  }

  interface ThrowingSupplier {

    // See Dispatcher.LegacyAsyncDispatcher for an explanation of why there aren't really any
    // useful testable guarantees about the behavior of that dispatcher in a multithreaded
    // environment. Here we simply test that all the expected dispatches happened in some order.
    assertThat(dispatchedSubscribers).containsExactly(i1, i2, i3, s1, s1, s1, s1, s2, s2, s2, s2);
  }

import java.util.concurrent.TimeoutException;
import junit.framework.AssertionFailedError;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/** Replacements for JUnit's {@code assertThrows} that work under GWT/J2CL. */
@GwtCompatible
@NullMarked
final class ReflectionFreeAssertThrows {
  interface ThrowingRunnable {
    void run() throws Throwable;
  }

  interface ThrowingSupplier {