feat: merkle proof spec test (#496)

lib/lambda_ethereum_consensus/state_transition/predicates.ex

@@ -123,11 +123,14 @@ defmodule LambdaEthereumConsensus.StateTransition.Predicates do
           SszTypes.root()
         ) :: boolean
   def is_valid_merkle_branch?(leaf, branch, depth, index, root) do
-    root ==
-      branch
-      |> Enum.take(depth)
-      |> Enum.with_index()
-      |> Enum.reduce(leaf, fn {v, i}, value -> hash_merkle_node(v, value, index, i) end)
+    root == generate_merkle_proof(leaf, branch, depth, index)
+  end
+
+  def generate_merkle_proof(leaf, branch, depth, index) do
+    branch
+    |> Enum.take(depth)
+    |> Enum.with_index()
+    |> Enum.reduce(leaf, fn {v, i}, value -> hash_merkle_node(v, value, index, i) end)
   end
 
   defp hash_merkle_node(value_1, value_2, index, i) do

lib/spec/runners/light_client.ex

@@ -0,0 +1,52 @@
+defmodule LightClientTestRunner do
+  alias LambdaEthereumConsensus.StateTransition.Predicates
+  use ExUnit.CaseTemplate
+  use TestRunner
+
+  @moduledoc """
+  Runner for LightClient test cases. See: https://github.com/ethereum/consensus-specs/tree/dev/tests/formats/light_client
+  """
+
+  # Remove handler from here once you implement the corresponding functions
+  @disabled_handlers [
+    # "single_merkle_proof",
+    "sync",
+    "update_ranking"
+  ]
+
+  @impl TestRunner
+  def skip?(%SpecTestCase{} = testcase) do
+    Enum.member?(@disabled_handlers, testcase.handler)
+  end
+
+  @impl TestRunner
+  def run_test_case(%SpecTestCase{} = testcase) do
+    handle(testcase.handler, testcase)
+  end
+
+  defp handle("single_merkle_proof", testcase) do
+    case_dir = SpecTestCase.dir(testcase)
+
+    object_root =
+      SpecTestUtils.read_ssz_from_file!(
+        case_dir <> "/object.ssz_snappy",
+        String.to_existing_atom("Elixir.SszTypes." <> testcase.suite)
+      )
+      |> Ssz.hash_tree_root!()
+
+    %{leaf: leaf, leaf_index: leaf_index, branch: branch} =
+      YamlElixir.read_from_file!(case_dir <> "/proof.yaml")
+      |> SpecTestUtils.sanitize_yaml()
+
+    res =
+      Predicates.is_valid_merkle_branch?(
+        leaf,
+        branch,
+        Constants.deposit_contract_tree_depth() + 1,
+        leaf_index,
+        object_root
+      )
+
+    assert true == res
+  end
+end