tests: simplify forkchoice api tests (leanEthereum#440)

Author: tcoratger

tests/api/endpoints/test_fork_choice.py

@@ -1,7 +1,11 @@
 """Tests for the fork choice endpoint."""
 
+from __future__ import annotations
+
 import httpx
 
+ZERO_ROOT = "0x" + "00" * 32
+
 
 def get_fork_choice(server_url: str) -> httpx.Response:
     """Fetch fork choice tree from the server."""
@@ -25,92 +29,24 @@ def test_content_type_is_json(self, server_url: str) -> None:
         content_type = response.headers.get("content-type", "")
         assert "application/json" in content_type
 
-    def test_has_nodes(self, server_url: str) -> None:
-        """Fork choice response has a nodes array."""
-        data = get_fork_choice(server_url).json()
-
-        assert "nodes" in data
-        assert isinstance(data["nodes"], list)
-        assert len(data["nodes"]) > 0
-
-    def test_node_structure(self, server_url: str) -> None:
-        """Each node has root, slot, parent_root, proposer_index, and weight."""
-        data = get_fork_choice(server_url).json()
-        node = data["nodes"][0]
-
-        assert isinstance(node["root"], str)
-        assert node["root"].startswith("0x")
-        assert len(node["root"]) == 66
-
-        assert isinstance(node["slot"], int)
-        assert node["slot"] >= 0
-
-        assert isinstance(node["parent_root"], str)
-        assert node["parent_root"].startswith("0x")
-        assert len(node["parent_root"]) == 66
-
-        assert isinstance(node["proposer_index"], int)
-        assert node["proposer_index"] >= 0
-
-        assert isinstance(node["weight"], int)
-        assert node["weight"] >= 0
-
-    def test_has_head(self, server_url: str) -> None:
-        """Fork choice response has a valid head root."""
-        data = get_fork_choice(server_url).json()
-
-        assert "head" in data
-        assert isinstance(data["head"], str)
-        assert data["head"].startswith("0x")
-        assert len(data["head"]) == 66
-
-    def test_has_justified_checkpoint(self, server_url: str) -> None:
-        """Fork choice response has a justified checkpoint with slot and root."""
-        data = get_fork_choice(server_url).json()
-
-        assert "justified" in data
-        justified = data["justified"]
-
-        assert isinstance(justified["slot"], int)
-        assert justified["slot"] >= 0
-
-        assert isinstance(justified["root"], str)
-        assert justified["root"].startswith("0x")
-        assert len(justified["root"]) == 66
-
-    def test_has_finalized_checkpoint(self, server_url: str) -> None:
-        """Fork choice response has a finalized checkpoint with slot and root."""
-        data = get_fork_choice(server_url).json()
-
-        assert "finalized" in data
-        finalized = data["finalized"]
-
-        assert isinstance(finalized["slot"], int)
-        assert finalized["slot"] >= 0
-
-        assert isinstance(finalized["root"], str)
-        assert finalized["root"].startswith("0x")
-        assert len(finalized["root"]) == 66
-
-    def test_has_safe_target(self, server_url: str) -> None:
-        """Fork choice response has a valid safe_target root."""
-        data = get_fork_choice(server_url).json()
-
-        assert "safe_target" in data
-        assert isinstance(data["safe_target"], str)
-        assert data["safe_target"].startswith("0x")
-        assert len(data["safe_target"]) == 66
-
-    def test_has_validator_count(self, server_url: str) -> None:
-        """Fork choice response has a non-negative validator count."""
-        data = get_fork_choice(server_url).json()
-
-        assert "validator_count" in data
-        assert isinstance(data["validator_count"], int)
-        assert data["validator_count"] >= 0
-
-    def test_head_is_in_nodes(self, server_url: str) -> None:
-        """The head root appears in the nodes list."""
-        data = get_fork_choice(server_url).json()
-        node_roots = {node["root"] for node in data["nodes"]}
-        assert data["head"] in node_roots
+    def test_fork_choice_response(self, server_url: str) -> None:
+        """Fork choice response matches expected genesis-only tree structure."""
+        data = get_fork_choice(server_url).json()
+        genesis_root = data["head"]
+
+        assert data == {
+            "nodes": [
+                {
+                    "root": genesis_root,
+                    "slot": 0,
+                    "parent_root": ZERO_ROOT,
+                    "proposer_index": 0,
+                    "weight": 0,
+                },
+            ],
+            "head": genesis_root,
+            "justified": {"slot": 0, "root": genesis_root},
+            "finalized": {"slot": 0, "root": genesis_root},
+            "safe_target": genesis_root,
+            "validator_count": 3,
+        }