AlterImpl extends BaseSqlPart implements Alter { @Nullable @Override public SqlPart previous() { return null; }  @NotNull @Override AlterTable table(@NotNull final String tableName); @NotNull @Override AlterTable table(@Nullable final String databaseName, @NotNull final String tableName); @Override void prependTo(@NotNull final RawSqlBuilder builder); @Nullable @Override SqlPart previous();  }
@Test public void previousIsNull() { SqlPart previous = mAlter.previous(); assertThat(previous, is(nullValue())); }