eth2.0-specs/tests/formats/fork_choice/README.md

Fork choice tests

The aim of the fork choice tests is to provide test coverage of the various components of the fork choice.

Test case format

meta.yaml

description: string    -- Optional. Description of test case, purely for debugging purposes.
bls_setting: int       -- see general test-format spec.

anchor_state.ssz_snappy

An SSZ-snappy encoded BeaconState, the state to initialize store with get_forkchoice_store(anchor_state: BeaconState, anchor_block: BeaconBlock) helper.

anchor_block.ssz_snappy

An SSZ-snappy encoded BeaconBlock, the block to initialize store with get_forkchoice_store(anchor_state: BeaconState, anchor_block: BeaconBlock) helper.

steps.yaml

The steps to execute in sequence. There may be multiple items of the following types:

on_tick execution step

The parameter that is required for executing on_tick(store, time).

{
    tick: int       -- to execute `on_tick(store, time)`.
    valid: bool     -- optional, default to `true`.
                       If it's `false`, this execution step is expected to be invalid.
}

After this step, the store object may have been updated.

on_attestation execution step

The parameter that is required for executing on_attestation(store, attestation).

{
    attestation: string  -- the name of the `attestation_<32-byte-root>.ssz_snappy` file.
                            To execute `on_attestation(store, attestation)` with the given attestation.
    valid: bool          -- optional, default to `true`.
                            If it's `false`, this execution step is expected to be invalid.
}

The file is located in the same folder (see below).

After this step, the store object may have been updated.

on_block execution step

The parameter that is required for executing on_block(store, block).

{
    block: string  -- the name of the `block_<32-byte-root>.ssz_snappy` file.
                      To execute `on_block(store, block)` with the given attestation.
    valid: bool    -- optional, default to `true`.
                      If it's `false`, this execution step is expected to be invalid.
}  

The file is located in the same folder (see below).

After this step, the store object may have been updated.

on_merge_block execution

Adds PowBlock data which is required for executing on_block(store, block).

{
    pow_block: string  -- the name of the `pow_block_<32-byte-root>.ssz_snappy` file.
                          To be used in `get_pow_block` lookup
}  

The file is located in the same folder (see below). PowBlocks should be used as return values for get_pow_block(hash: Hash32) -> PowBlock function if hashes match.

Checks step

The checks to verify the current status of store.

checks: {<store_attibute>: value}  -- the assertions.

<store_attibute> is the field member or property of Store object that maintained by client implementation. Currently, the possible fields included:

head: {
    slot: int,
    root: string,             -- Encoded 32-byte value from get_head(store)
}
time: int                     -- store.time
genesis_time: int             -- store.genesis_time
justified_checkpoint: {
    epoch: int,               -- Integer value from store.justified_checkpoint.epoch
    root: string,             -- Encoded 32-byte value from store.justified_checkpoint.root
}
finalized_checkpoint: {
    epoch: int,               -- Integer value from store.finalized_checkpoint.epoch
    root: string,             -- Encoded 32-byte value from store.finalized_checkpoint.root
}
best_justified_checkpoint: {
    epoch: int,               -- Integer value from store.best_justified_checkpoint.epoch
    root: string,             -- Encoded 32-byte value from store.best_justified_checkpoint.root
}
proposer_boost_root: string   -- Encoded 32-byte value from store.proposer_boost_root

For example:

- checks:
    time: 192
    head: {slot: 32, root: '0xdaa1d49d57594ced0c35688a6da133abb086d191a2ebdfd736fad95299325aeb'}
    justified_checkpoint: {epoch: 3, root: '0xc25faab4acab38d3560864ca01e4d5cc4dc2cd473da053fbc03c2669143a2de4'}
    finalized_checkpoint: {epoch: 2, root: '0x40d32d6283ec11c53317a46808bc88f55657d93b95a1af920403187accf48f4f'}
    best_justified_checkpoint: {epoch: 3, root: '0xc25faab4acab38d3560864ca01e4d5cc4dc2cd473da053fbc03c2669143a2de4'}
    proposer_boost_root: '0xdaa1d49d57594ced0c35688a6da133abb086d191a2ebdfd736fad95299325aeb'

Note: Each checks step may include one or multiple items. Each item has to be checked against the current store.

attestation_<32-byte-root>.ssz_snappy

<32-byte-root> is the hash tree root of the given attestation.

Each file is an SSZ-snappy encoded Attestation.

block_<32-byte-root>.ssz_snappy

<32-byte-root> is the hash tree root of the given block.

Each file is an SSZ-snappy encoded SignedBeaconBlock.

Condition

1. Deserialize anchor_state.ssz_snappy and anchor_block.ssz_snappy to initialize the local store object by with get_forkchoice_store(anchor_state, anchor_block) helper.
2. Iterate sequentially through steps.yaml
   • For each execution, look up the corresponding ssz_snappy file. Execute the corresponding helper function on the current store.
     • For the on_block execution step: if len(block.message.body.attestations) > 0, execute each attestation with on_attestation(store, attestation) after executing on_block(store, block).
   • For each checks step, the assertions on the current store must be satisfied.