### Question:
AttributeContainerMutable implements AttributeContainer { public boolean remove(Attribute a) { return a != null && atts.remove(a); } AttributeContainerMutable(@Nullable String name);  AttributeContainerMutable(@Nullable String name, Iterable<Attribute> from); static AttributeContainerMutable copyFrom(@Nullable AttributeContainer from); void setName(@Nullable String name); @Override @Nullable String getName(); @Override Iterator<Attribute> iterator(); Attribute addAttribute(Attribute att); Attribute addAttribute(String name, String value); Attribute addAttribute(String name, Number value); void addAll(Iterable<Attribute> atts); @Override String findAttributeString(String attName, String defaultValue); @Override Attribute findAttribute(String name); @Override Attribute findAttributeIgnoreCase(String name); @Override double findAttributeDouble(String attName, double defaultValue); @Override int findAttributeInteger(String attName, int defaultValue); boolean remove(Attribute a); boolean replace(Attribute a, String newName); AttributeContainerMutable clear(); boolean removeAttribute(String attName); boolean removeAttributeIgnoreCase(String attName); AttributeContainer toImmutable(); @Override boolean isEmpty();  }### Answer:
@Test public void testRemove() { AttributeContainerMutable attc = new AttributeContainerMutable("container"); attc.addAttribute(new Attribute("name", "value")); attc.addAttribute(new Attribute("name2", "value2")); attc.addAttribute("name3", 123); assertThat(Iterables.size(attc)).isEqualTo(3); assertThat(attc.removeAttribute("name2")).isTrue(); assertThat(Iterables.size(attc)).isEqualTo(2); assertThat(attc.findAttribute("name2")).isNull(); assertThat(attc.removeAttribute("name2")).isFalse(); assertThat(attc.remove(new Attribute("name", "value"))).isTrue(); assertThat(Iterables.size(attc)).isEqualTo(1); assertThat(attc.findAttribute("name")).isNull(); assertThat(attc.remove(new Attribute("name", "value"))).isFalse(); assertThat(attc.removeAttributeIgnoreCase("NAMe3")).isTrue(); assertThat(Iterables.size(attc)).isEqualTo(0); assertThat(attc.findAttribute("name3")).isNull(); assertThat(attc.removeAttributeIgnoreCase("name3")).isFalse(); }