copy(buf[c1:], r.buf[0:c2])
	}

	return buf
}

// IsFull returns this ringbuffer is full.
func (r *RingBuffer) IsFull() bool {
	r.mu.Lock()
	defer r.mu.Unlock()

	return r.isFull
}

// IsEmpty returns this ringbuffer is empty.
func (r *RingBuffer) IsEmpty() bool {
	r.mu.Lock()
	defer r.mu.Unlock()

	return !r.isFull && r.w == r.r
}

	}
	// check empty or full
	if rb.IsEmpty() {
		t.Fatalf("expect IsEmpty is false but got true")
	}
	if rb.IsFull() {
		t.Fatalf("expect IsFull is false but got true")
	}

	// write to, isFull
	err = rb.WriteByte('b')
	if err != nil {
		t.Fatalf("WriteByte failed: %v", err)
	}
	if rb.Length() != 2 {

    assertThat(spec.initialCapacity).isNull();
    assertThat(spec.maximumSize).isNull();
    assertThat(spec.maximumWeight).isNull();
    assertThat(spec.concurrencyLevel).isNull();
    assertThat(spec.keyStrength).isNull();
    assertThat(spec.valueStrength).isNull();
    assertThat(spec.writeExpirationTimeUnit).isNull();
    assertThat(spec.accessExpirationTimeUnit).isNull();

    assertThat(parse(url, "a\u0000b=cd")).isNull()
    assertThat(parse(url, "ab=c\u0000d")).isNull()
    assertThat(parse(url, "a\u0001b=cd")).isNull()
    assertThat(parse(url, "ab=c\u0001d")).isNull()
    assertThat(parse(url, "a\u0009b=cd")).isNull()
    assertThat(parse(url, "ab=c\u0009d")).isNull()
    assertThat(parse(url, "a\u001fb=cd")).isNull()
    assertThat(parse(url, "ab=c\u001fd")).isNull()

  }

  /*
   * Tests for Predicates.isNull()
   */

  public void testIsNull_apply() {
    Predicate<@Nullable Integer> isNull = Predicates.isNull();
    assertTrue(isNull.apply(null));
    assertFalse(isNull.apply(1));
  }

  public void testIsNull_equality() {
    new EqualsTester()
        .addEqualityGroup(Predicates.isNull(), Predicates.isNull())
        .addEqualityGroup(Predicates.notNull())

        .url("https://square.com")
        .build()
    assertThat(request.tag<Any>()).isNull()
    assertThat(request.tag(Any::class)).isNull()
    assertThat(request.tag(String::class)).isNull()

    // Alternate access APIs also work.
    assertThat(request.tag<String>()).isNull()
    assertThat(request.tag(String::class)).isNull()
  }

  @Test
  fun defaultTag() {
    val tag = "1234"
    val request =

        SmbTreeImpl tree = mock(SmbTreeImpl.class);
        doReturn(tree).when(session).getSmbTree(eq("LOGON$"), isNull());

        // Act
        session.treeConnectLogon();

        // Assert: treeConnect invoked once with null params
        verify(tree, times(1)).treeConnect(isNull(), isNull());
        // Close of try-with-resources should call close on the mock
        verify(tree, times(1)).close();
    }

    assertThat(Ints.tryParse("")).isNull();
    assertThat(Ints.tryParse("-")).isNull();
    assertThat(Ints.tryParse("+1")).isNull();
    assertThat(Ints.tryParse("9999999999999999")).isNull();
    assertWithMessage("Max integer + 1")
        .that(Ints.tryParse(Long.toString(((long) GREATEST) + 1)))
        .isNull();
    assertWithMessage("Max integer * 10")

        .build()
    assertThat(request.tag()).isNull()
    assertThat(request.tag(Any::class.java)).isNull()
    assertThat(request.tag(UUID::class.java)).isNull()
    assertThat(request.tag(String::class.java)).isNull()

    // Alternate access APIs also work.
    assertThat(request.tag<String>()).isNull()
    assertThat(request.tag(String::class)).isNull()
  }

  @Test
  fun defaultTag() {

    assertThat(map.containsKey(one)).isFalse();
    assertThat(map.containsValue(one)).isFalse();
    assertThat(map.putIfAbsent(two, three)).isNull();
    assertThat(map.remove(two)).isSameInstanceAs(three);
    assertThat(map.put(three, one)).isNull();
    assertThat(map.put(one, two)).isNull();

    assertThat(map).containsEntry(three, one);
    assertThat(map).containsEntry(one, two);