# Credits to Danny Ryan (Ethereum Foundation)
---

title: Sample Ethereum 2.0 Beacon Chain Test
summary: Basic, functioning fork choice rule for Ethereum 2.0
test_suite: prysm
test_cases:
  - config:
      validator_count: 100
      cycle_length: 8
      shard_count: 32
      min_committee_size: 8
    slots:
      # "slot_number" has a minimum of 1
      - slot_number: 1
        new_block:
          id: A
          # "*" is used for the genesis block
          parent: "*"
        attestations:
          - block: A
            # the following is a shorthand string for [0, 1, 2, 3, 4, 5]
            validators: "0-5"
      - slot_number: 2
        new_block:
          id: B
          parent: A
        attestations:
          - block: B
            validators: "0-5"
      - slot_number: 3
        new_block:
          id: C
          parent: A
        attestations:
          # attestation "committee_slot" defaults to the slot during which the attestation occurs
          - block: C
            validators: "2-7"
          # default "committee_slot" can be directly overridden
          - block: C
            committee_slot: 2
            validators: "6, 7"
      - slot_number: 4
        new_block:
          id: D
          parent: C
        attestations:
          - block: D
            validators: "1-4"
      # slots can be skipped entirely (5 in this case)
      - slot_number: 6
        new_block:
          id: E
          parent: D
        attestations:
          - block: E
            validators: "0-4"
          - block: B
            validators: "5, 6, 7"
    results:
      head: E
      last_justified_block: "*"
      last_finalized_block: "*"