Oleksandr Stepanenko

@skribe

So here are my testing results:

Seed 5810358736862867128

1.13.1-pre1

Skeleton /tp 172 16 21

Skeleton /tp 165 41 220

Skeleton /tp 215 13 458

Zombie /tp 291 31 395

Skeleton /tp 385 31 422

1.12.2

Zombie /tp 64 42 493

Spider /tp 103 26 51

Zombie /tp 139 37 198

Zombie /tp 153 23 490

Zombie /tp 241 27 468

Zombie /tp 384 26 166

Zombie /tp 390 33 474

Skeleton /tp 476 11 491

Skeleton /tp 492 30 410

Seed 7452477466514423488

1.13.1-pre1

Zombie /tp 13 50 12 (Notch Apple in a chest by the way)

Skeleton /tp 188 39 72

Skeleton /tp 199 53 62

Spider /tp 270 33 389

Zombie /tp 414 25 461

Zombie /tp 509 44 429

1.12.2

Zombie /tp 60 69 51

Spider /tp 70 57 60

Spider /tp 81 30 213

Skeleton /tp 233 52 268

Zombie /tp 408 45 60

The first seed has its 0.0 region almost entirely under the ocean. Maybe dungeons don't generate in the new flooded caves? Thus there are quite less of them in the new version under such conditions. Still there are a few of them, not only one.

The second seed however has more dungeons in the new version than in the previous.

It is worth noting that choosing only one region file with so few dungeons inside leads to considerable statistical errors so I would advise to use atleast 3x3 regions if you can automate the process in any way. To conclude I have tested 6 seeds so far (one of them I plan to play on - with 4 region files) and only one of them has less dungeons than in previous version. And that seed may has many flooded caves in the area 1.12.2 version doesn't have.

@skribe, let me test it myself. Please tell me your seed and the range of coordinates where you were looking for dungeons. I am genuinely interested to have all major world generation issues resolved before I create a new longterm world.

It can be easy tested:

In 1.13+ choose a seed, generate a region file completely (for example r.0.0), then search in the region file with NBTExplorer for Name:"id", Value:"minecraft:mob_spawner". Write down zombie, skeleton, spider spawner counts.

In 1.12.2 use the same seed, generate the same region file, open it in MCEdit-Unified, select 32x32 chunks corresponding to the region and search for block "monster spawner" with BlockFinder_v1 filter. Teleport to the coordinates and write down the count and the type of the spawners.

I have tested 3 seeds so far and it seems 1.13+ versions generate not less but more dungeons! Just in different locations. Anyone may test more seeds, more biomes and if it is the case, then I'd say it works as intended.

UPD. Seed -2095774850092795097, regions 0.0, 0.1, 1.0, 1.1 (coordinates x, z ∈ [0, 1024)).
Here are my results for the numbers of all types of mob spawners in the area (counted manually by the methods described in this comment):