GroupByImpl extends BaseFinishedSelectStatement implements GroupBy { @Nullable @Override public SqlPart previous() { return mPrevious; } GroupByImpl(@NotNull final String expression, @NotNull final SqlPart previous); @NotNull @Override OrderBy orderBy(@NotNull final String... terms); @NotNull @Override Limit limit(final long limit); @Override void prependTo(@NotNull final RawSqlBuilder builder); @Nullable @Override SqlPart previous();  }
@Test public void previous_returnsProperItem() { SqlPart sqlPart = mock(SqlPart.class); GroupByImpl groupBy = new GroupByImpl("a", sqlPart); SqlPart result = groupBy.previous(); assertThat(result, is(sqlPart)); }