Java Mongo Filter equality checks

[Albert Kam]

I'm currently involved with testing dynamically generated query filters.

It seems that the filters havent provided an implementation for equality check.

Therefore, this test will fail:

// does not pass

@Test

public void testFilterEqualityByFilterType() {

assertEquals(and(eq("hello", "world")), and(eq("hello", "world")));

}

But this does pass:

@Test

public void testFilterEqualityByString() {

assertEquals(and(eq("hello", "world")).toString(),

and(eq("hello", "world")).toString());

}

As a tester, i'd be more comfortable checking on equality rather than string.

Hopefully this could serve as a good input for future improvements.

Thank you guys for developing such great products.

[Jeff Yemin]

The Filters API returns instances of the Bson interface, which are not reliably comparable for equality without providing an encoder for the values.  But you can easily do this via the Bson.toBsonDocument method.  Just pass the Bson instances to this helper method before comparing for equality:

   BsonDocument toBsonDocument(Bson bson) {
      return bson.toBsonDocument(BsonDocument.class,
              MongoClient.getDefaultCodecRegistry());  // or use a custom CodecRegistry instance
   }

      // passes now

   @Test
   public void testFilterEqualityByFilterType() {
      assertEquals(toBsonDocument(and(eq("hello", "world"))), toBsonDocument(and(eq("hello", "world"))));
   }