These units auto-attack upon spawn when having auto-attack set to "never":
1. Beastmaster's Boar
2. Lycan's Wolves
3. Dark Troll Summoner's Skeleton Warriors
4. Doom's Doom Shards
5. Brewmaster's Earth, Storm and Fire spirits
6. Lone Druid's Spirit Bear
They should not. All other summons only auto-attack on spawn when the auto-attack is set to "standard" or "always", but don't when set to "never". Only Undying's Zombies and ward type units (plague wards, serpent wards, death wards) should always start attacking on spawn.
Here you can see the above named units auto-attacking as they get summoned, even with auto-attack being set to "never".
And here you can see all other summons. They do not auto-attack upon spawn when set to "never".
1. Beastmaster's Boar
2. Lycan's Wolves
3. Dark Troll Summoner's Skeleton Warriors
4. Doom's Doom Shards
5. Brewmaster's Earth, Storm and Fire spirits
6. Lone Druid's Spirit Bear
They should not. All other summons only auto-attack on spawn when the auto-attack is set to "standard" or "always", but don't when set to "never". Only Undying's Zombies and ward type units (plague wards, serpent wards, death wards) should always start attacking on spawn.
Here you can see the above named units auto-attacking as they get summoned, even with auto-attack being set to "never".
And here you can see all other summons. They do not auto-attack upon spawn when set to "never".