@Test public void testFields() throws Exception { MongoItemReader<String> reader = getBasicBuilder() .fields("{name : 1, age : 1, _id: 0}") .build(); when(this.template.find(this.queryContainer.capture(), eq(String.class))).thenReturn(new ArrayList<>()); assertNull("reader should not return result", reader.read()); Query query = this.queryContainer.getValue(); assertEquals(1, query.getFieldsObject().get("name")); assertEquals(1, query.getFieldsObject().get("age")); assertEquals(0, query.getFieldsObject().get("_id")); }