diff --git a/mysticeti/blocks/blck.nim b/mysticeti/blocks/blck.nim
index 3d4b68e..0d5036f 100644
--- a/mysticeti/blocks/blck.nim
+++ b/mysticeti/blocks/blck.nim
@@ -10,14 +10,14 @@ type
     parents: seq[BlockId[Hashing]]
     transactions: seq[Transaction]
 
-func new*(
-  _: type Block,
+func new*[Hashing](
+  _: type Block[Hashing];
   author: CommitteeMember,
   round: uint64,
-  parents: seq[BlockId],
+  parents: seq[BlockId[Hashing]],
   transactions: seq[Transaction]
 ): auto =
-  Block[BlockId.Hashing](
+  Block[Hashing](
     author: author,
     round: round,
     parents: parents,
diff --git a/mysticeti/validator/round.nim b/mysticeti/validator/round.nim
index 8fd6377..9fa004b 100644
--- a/mysticeti/validator/round.nim
+++ b/mysticeti/validator/round.nim
@@ -9,6 +9,7 @@ type Round*[Hashing] = ref object
   slots: seq[ProposerSlot[Hashing]]
 
 func new*(T: type Round, number: uint64, slots: int): T =
+  assert slots > 0
   type Slot = ProposerSlot[T.Hashing]
   let slots = newSeqWith(slots, Slot.new())
   T(number: number, slots: slots)
@@ -42,7 +43,7 @@ iterator slots*(round: Round): auto =
     yield round[member]
 
 iterator proposals*(round: Round): auto =
-  for slot in round.slots:
+  for slot in slots(round):
     for proposal in slot.proposals:
       yield proposal
 
@@ -71,11 +72,15 @@ func find*(round: Round, blockId: BlockId): auto =
 func findAnchor*(round: Round): auto =
   var next = round.find(round.number + 3)
   while current =? next:
-    for slot in current.slots:
+    for slot in slots(current):
       if slot.status in [SlotStatus.undecided, SlotStatus.commit]:
         return some slot
     next = current.next
 
+func addProposal*(round: Round, blck: Block): auto =
+  assert blck.round == round.number
+  round[blck.author].addProposal(blck)
+
 func remove*(round: Round) =
   if previous =? round.previous:
     previous.next = round.next
@@ -83,6 +88,3 @@ func remove*(round: Round) =
     next.previous = round.previous
   round.next = none Round
   round.previous = none Round
-
-func addProposal*(round: Round, blck: Block): auto =
-  round[blck.author].addProposal(blck)
diff --git a/tests/mysticeti/examples.nim b/tests/mysticeti/examples.nim
index 454f238..b2347f1 100644
--- a/tests/mysticeti/examples.nim
+++ b/tests/mysticeti/examples.nim
@@ -28,12 +28,14 @@ proc example*(T: type BlockId): T =
   let hash = Hash[T.Hashing].example
   BlockId.new(author, round, hash)
 
-proc example*(T: type Block): T =
-  let author = CommitteeMember.example
-  let round = uint64.example
+proc example*(
+  T: type Block,
+  author = CommitteeMember.example,
+  round = uint64.example
+): T =
   let parents = seq[BlockId[T.Hashing]].example
   let transactions = seq[Transaction].example
-  Block.new(author, round, parents, transactions)
+  T.new(author, round, parents, transactions)
 
 proc example*[T](_: type seq[T], length=0..10): seq[T] =
   let size = rand(length)
diff --git a/tests/mysticeti/validator/testRound.nim b/tests/mysticeti/validator/testRound.nim
index 0bd8729..91a3217 100644
--- a/tests/mysticeti/validator/testRound.nim
+++ b/tests/mysticeti/validator/testRound.nim
@@ -1,10 +1,123 @@
 import ../basics
 import mysticeti
-import mysticeti/validator/rounds
+import mysticeti/blocks
+import mysticeti/validator/slots
+import mysticeti/validator/round
 
 suite "Validator Round":
 
-  type Round = rounds.Round[MockHashing]
+  type Round = round.Round[MockHashing]
+  type Block = mysticeti.Block[MockHashing]
+
+  test "rounds have a number":
+    check Round.new(0, 1).number == 0
+    check Round.new(42, 1).number == 42
+    check Round.new(1337, 1).number == 1337
+
+  test "round has a fixed number of slots":
+    check toSeq(Round.new(0, 1).slots).len == 1
+    check toSeq(Round.new(0, 42).slots).len == 42
+    check toSeq(Round.new(0, 1337).slots).len == 1337
+
+  test "round requires at least one slot":
+    expect Defect:
+      discard Round.new(0, 0)
+
+  test "round has a slot for each committee member":
+    let round = Round.new(0, 4)
+    check not isNil round[CommitteeMember(0)]
+    check not isNil round[CommitteeMember(1)]
+    check not isNil round[CommitteeMember(2)]
+    check not isNil round[CommitteeMember(3)]
+    expect Defect:
+      discard round[CommitteeMember(4)]
+
+  test "round stores proposed blocks in the corresponding slots":
+    let round = Round.new(0, 4)
+    let block1 = Block.example(author = CommitteeMember(1), round = 0)
+    let block2 = Block.example(author = CommitteeMember(2), round = 0)
+    let block3 = Block.example(author = CommitteeMember(2), round = 0)
+    round.addProposal(block1)
+    round.addProposal(block2)
+    round.addProposal(block3)
+    let slot1 = round[CommitteeMember(1)]
+    check slot1.proposals.len == 1
+    check slot1.proposals[0].blck == block1
+    let slot2 = round[CommitteeMember(2)]
+    check slot2.proposals.len == 2
+    check slot2.proposals[0].blck == block2
+    check slot2.proposals[1].blck == block3
+
+  test "round does not accept blocks meant for different rounds":
+    let blck = Block.example(author = CommitteeMember(0), round = 42)
+    let round42 = Round.new(42, 4)
+    let round43 = Round.new(43, 4)
+    round42.addProposal(blck)
+    expect Defect:
+      round43.addProposal(blck)
+
+  test "round is part of a doubly linked list":
+    let first = Round.new(0, 4)
+    let second = Round.new(first)
+    let third = Round.new(second)
+    check first.previous == none Round
+    check first.next == some second
+    check second.previous == some first
+    check second.next == some third
+    check third.previous == some second
+    check third.next == none Round
+
+  test "doubly linked list has increasing round numbers":
+    let first = Round.new(42, 4)
+    let second = Round.new(first)
+    let third = Round.new(second)
+    check first.number == 42
+    check second.number == 43
+    check third.number == 44
+
+  test "doubly linked list can be used to find a round by its number":
+    let first = Round.new(42, 4)
+    let second = Round.new(first)
+    let third = Round.new(second)
+    for round in [first, second, third]:
+      check round.find(41'u64) == none Round
+      check round.find(42'u64) == some first
+      check round.find(43'u64) == some second
+      check round.find(44'u64) == some third
+      check round.find(45'u64) == none Round
+
+  test "doubly linked list can be used to find a block":
+    let first = Round.new(42, 4)
+    let second = Round.new(first)
+    let third = Round.new(second)
+    let block1 = Block.example(author = CommitteeMember(1), round = 42)
+    let block2 = Block.example(author = CommitteeMember(2), round = 43)
+    let block3 = Block.example(author = CommitteeMember(2), round = 43)
+    first.addProposal(block1)
+    second.addProposal(block2)
+    second.addProposal(block3)
+    for round in [first, second, third]:
+      check round.find(block1.id) == some block1
+      check round.find(block2.id) == some block2
+      check round.find(block3.id) == some block3
+      check round.find(Block.example.id) == none Block
+
+  test "round can be removed from a doubly linked list":
+    let first = Round.new(42, 4)
+    let second = Round.new(first)
+    let third = Round.new(second)
+    second.remove()
+    check first.previous == none Round
+    check first.next == some third
+    check second.previous == none Round
+    check second.next == none Round
+    check third.previous == some first
+    check third.next == none Round
+    third.remove()
+    check first.previous == none Round
+    check first.next == none Round
+    check third.previous == none Round
+    check third.next == none Round
 
   test "members are ordered round-robin for each round":
     var round: Round
@@ -18,3 +131,46 @@ suite "Validator Round":
     check toSeq(round.members) == @[3, 0, 1, 2].mapIt(CommitteeMember(it))
     round = Round.new(4, 4)
     check toSeq(round.members) == @[0, 1, 2, 3].mapIt(CommitteeMember(it))
+
+  test "slots are ordered round-robin too":
+    let round = Round.new(2, 4)
+    let slots = toSeq(round.slots)
+    check slots[0] == round[CommitteeMember(2)]
+    check slots[1] == round[CommitteeMember(3)]
+    check slots[2] == round[CommitteeMember(0)]
+    check slots[3] == round[CommitteeMember(1)]
+
+  test "proposals are ordered round-robin as well":
+    var blocks: seq[Block]
+    blocks.add(Block.example(author = CommitteeMember(0), round = 2))
+    blocks.add(Block.example(author = CommitteeMember(0), round = 2))
+    blocks.add(Block.example(author = CommitteeMember(1), round = 2))
+    blocks.add(Block.example(author = CommitteeMember(1), round = 2))
+    blocks.add(Block.example(author = CommitteeMember(2), round = 2))
+    blocks.add(Block.example(author = CommitteeMember(2), round = 2))
+    blocks.add(Block.example(author = CommitteeMember(3), round = 2))
+    blocks.add(Block.example(author = CommitteeMember(3), round = 2))
+    let round = Round.new(2, 4)
+    for blck in blocks:
+      round.addProposal(blck)
+    let proposals = toSeq(round.proposals)
+    check proposals[0].blck == blocks[4]
+    check proposals[1].blck == blocks[5]
+    check proposals[2].blck == blocks[6]
+    check proposals[3].blck == blocks[7]
+    check proposals[4].blck == blocks[0]
+    check proposals[5].blck == blocks[1]
+    check proposals[6].blck == blocks[2]
+    check proposals[7].blck == blocks[3]
+
+  test "doubly linked list can be used to find the anchor for a round":
+    let proposing = Round.new(2, 4)
+    let voting = Round.new(proposing)
+    let certifying = Round.new(voting)
+    let anchoring = Round.new(certifying)
+    let orderedSlots = toSeq(anchoring.slots)
+    check proposing.findAnchor() == some orderedSlots[0]
+    orderedSlots[0].skip()
+    check proposing.findAnchor() == some orderedSlots[1]
+    orderedSlots[1].skip()
+    check proposing.findAnchor() == some orderedSlots[2]