### Question:
Where { public Where<T, ID> isNull(String columnName) throws SQLException { addClause(new IsNull(columnName, findColumnFieldType(columnName))); return this; } protected  Where(TableInfo<T, ID> tableInfo, StatementBuilder<T, ID> statementBuilder, DatabaseType databaseType); Where<T, ID> and(); Where<T, ID> and(Where<T, ID> first, Where<T, ID> second, Where<T, ID>... others); Where<T, ID> and(int numClauses); Where<T, ID> between(String columnName, Object low, Object high); Where<T, ID> eq(String columnName, Object value); Where<T, ID> ge(String columnName, Object value); Where<T, ID> gt(String columnName, Object value); Where<T, ID> in(String columnName, Iterable<?> objects); Where<T, ID> notIn(String columnName, Iterable<?> objects); Where<T, ID> in(String columnName, Object... objects); Where<T, ID> notIn(String columnName, Object... objects); Where<T, ID> in(String columnName, QueryBuilder<?, ?> subQueryBuilder); Where<T, ID> notIn(String columnName, QueryBuilder<?, ?> subQueryBuilder); Where<T, ID> exists(QueryBuilder<?, ?> subQueryBuilder); Where<T, ID> isNull(String columnName); Where<T, ID> isNotNull(String columnName); Where<T, ID> le(String columnName, Object value); Where<T, ID> lt(String columnName, Object value); Where<T, ID> like(String columnName, Object value); Where<T, ID> ne(String columnName, Object value); Where<T, ID> not(); Where<T, ID> not(Where<T, ID> comparison); Where<T, ID> or(); Where<T, ID> or(Where<T, ID> left, Where<T, ID> right, Where<T, ID>... others); Where<T, ID> or(int numClauses); Where<T, ID> idEq(ID id); Where<T, ID> idEq(Dao<OD, ?> dataDao, OD data); Where<T, ID> raw(String rawStatement, ArgumentHolder... args); Where<T, ID> rawComparison(String columnName, String rawOperator, Object value); PreparedQuery<T> prepare(); List<T> query(); GenericRawResults<String[]> queryRaw(); T queryForFirst(); String[] queryRawFirst(); long countOf(); CloseableIterator<T> iterator(); Where<T, ID> reset(); String getStatement(); @Override String toString();  }### Answer:
@Test public void testIsNull() throws Exception { Where<Foo, String> where = new Where<Foo, String>(createTableInfo(), null, databaseType); where.isNull(Foo.VAL_COLUMN_NAME); StringBuilder whereSb = new StringBuilder(); where.appendSql(null, whereSb, new ArrayList<ArgumentHolder>()); StringBuilder sb = new StringBuilder(); databaseType.appendEscapedEntityName(sb, Foo.VAL_COLUMN_NAME); sb.append(" IS NULL "); assertEquals(sb.toString(), whereSb.toString()); }