document genesis test vector format, fix missing label and assertion in tests

specs/test_formats/genesis/README.md

@@ -0,0 +1,8 @@
+# Genesis tests
+
+The aim of the genesis tests is to provide a baseline to test genesis-state initialization and test
+ if the proposed genesis-validity conditions are working.
+
+There are two handlers, documented individually:
+- [`validity`](./validity.md): Tests if a genesis state is valid, i.e. if it counts as trigger to launch.
+- [`initialization`](./initialization.md): Tests the initialization of a genesis state based on Eth1 data.

specs/test_formats/genesis/initialization.md

@@ -0,0 +1,22 @@
+# Genesis creation testing
+
+Tests the initialization of a genesis state based on Eth1 data.
+
+## Test case format
+
+```yaml
+description: string            -- description of test case, purely for debugging purposes
+bls_setting: int               -- see general test-format spec.
+eth1_block_hash: Bytes32       -- the root of the Eth-1 block, hex encoded, with prefix 0x
+eth1_timestamp: int            -- the timestamp of the block, in seconds.
+deposits: [Deposit]            -- list of deposits to build the genesis state with
+state: BeaconState             -- the expected genesis state.
+```
+
+To process this test, build a genesis state with the provided `eth1_block_hash`, `eth1_timestamp` and `deposits`:
+`initialize_beacon_state_from_eth1(eth1_block_hash, eth1_timestamp, deposits)`,
+ as described in the Beacon Chain specification.
+
+## Condition
+
+The resulting state should match the expected `state`.

specs/test_formats/genesis/validity.md

@@ -0,0 +1,19 @@
+# Genesis validity testing
+
+Tests if a genesis state is valid, i.e. if it counts as trigger to launch.
+
+## Test case format
+
+```yaml
+description: string    -- description of test case, purely for debugging purposes
+bls_setting: int       -- see general test-format spec.
+genesis: BeaconState   -- state to validate.
+is_valid: bool         -- true if the genesis state is deemed valid as to launch with, false otherwise.
+```
+
+To process the data, call `is_valid_genesis_state(genesis)`.
+
+
+## Condition
+
+The result of calling `is_valid_genesis_state(genesis)` should match the expected `is_valid` boolean.

test_libs/pyspec/eth2spec/test/genesis/test_is_valid_genesis_state.py

@@ -16,13 +16,13 @@ def create_valid_beacon_state(spec):
 def run_is_valid_genesis_state(spec, state, valid=True):
     """
     Run ``is_valid_genesis_state``, yielding:
-      - state ('state')
+      - genesis ('state')
       - is_valid ('is_valid')
-    If ``valid == False``, run expecting ``AssertionError``
     """
-    yield state
+    yield 'genesis', state
     is_valid = spec.is_valid_genesis_state(state)
     yield 'is_valid', is_valid
+    assert is_valid == valid
 
 
 @with_phases(['phase0'])