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.

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
}

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'}

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.