IntStack { public void clear() { n = 0; } IntStack(final int n); int size(); void clear();  }
@Test public void clear() throws Exception { IntStack stack = new IntStack(1); stack.push(1); assertThat(stack.peek(), is(1)); assertThat(stack.size(), is(1)); stack.push(2); assertThat(stack.peek(), is(2)); assertThat(stack.size(), is(2)); stack.push(4); assertThat(stack.peek(), is(4)); assertThat(stack.size(), is(3)); stack.clear(); assertThat(stack.size(), is(0)); stack.push(4); assertThat(stack.peek(), is(4)); assertThat(stack.size(), is(1)); stack.push(8); assertThat(stack.peek(), is(8)); assertThat(stack.size(), is(2)); stack.push(9); assertThat(stack.peek(), is(9)); assertThat(stack.size(), is(3)); }