SelectImpl extends BaseSqlPart implements Select { @Nullable @Override public SqlPart previous() { return null; } SelectImpl(@NotNull final String... columns); @NotNull @Override SelectFrom from(@NotNull final String tableName); @Override void prependTo(@NotNull final RawSqlBuilder builder); @Nullable @Override SqlPart previous();  }
@Test public void previous_returnsNull() { SelectImpl select = new SelectImpl(); SqlPart result = select.previous(); assertThat(result, is(nullValue())); }