feat(tests): derive cost model proposals from live protocol params

cardano_node_tests/tests/test_node_upgrade.py

@@ -15,6 +15,7 @@
 from cardano_node_tests.tests.tests_conway import conway_common
 from cardano_node_tests.utils import cluster_nodes
 from cardano_node_tests.utils import clusterlib_utils
+from cardano_node_tests.utils import cost_model_utils
 from cardano_node_tests.utils import governance_setup
 from cardano_node_tests.utils import governance_utils
 from cardano_node_tests.utils import helpers
@@ -132,7 +133,7 @@ def test_update_cost_models(
         Test updating Plutus cost models after node upgrade. Runs only on step 2 of upgrade
         testing sequence.
 
-        * Load cost model proposal from JSON file (PlutusV2 and PlutusV3 models)
+        * Generate cost model proposal from the running cluster's current protocol parameters
         * Get default governance data (DReps, committee members, pools)
         * Submit cost model update governance action
         * Vote and ratify the cost model update
@@ -141,7 +142,10 @@ def test_update_cost_models(
         """
         cluster = cluster_singleton
         temp_template = common.get_test_id(cluster)
-        cost_proposal_file = DATA_DIR / "cost_models_list_185_297_v2_v3.json"
+        cost_proposal_file = cost_model_utils.write_cost_model_proposal(
+            cost_models=cost_model_utils.get_current_cost_models(cluster),
+            dest=temptools.get_basetemp() / f"{temp_template}_cost_models.json",
+        )
 
         governance_data = governance_setup.get_default_governance(
             cluster_manager=cluster_manager, cluster_obj=cluster

cardano_node_tests/tests/tests_conway/test_pparam_update.py

@@ -17,11 +17,13 @@
 from cardano_node_tests.tests.tests_conway import conway_common
 from cardano_node_tests.utils import clusterlib_utils
 from cardano_node_tests.utils import configuration
+from cardano_node_tests.utils import cost_model_utils
 from cardano_node_tests.utils import dbsync_utils
 from cardano_node_tests.utils import governance_utils
 from cardano_node_tests.utils import helpers
 from cardano_node_tests.utils import submit_api
 from cardano_node_tests.utils import submit_utils
+from cardano_node_tests.utils import temptools
 from cardano_node_tests.utils.versions import VERSIONS
 
 LOGGER = logging.getLogger(__name__)
@@ -280,6 +282,11 @@ def test_pparam_update(  # noqa: C901
 
         * Vote to disapprove the actions
         * Submit a "protocol parameters update" action that will be enacted
+
+            - Cost model proposal is generated dynamically from the running cluster's
+              current protocol parameters, so no static fixture file needs updating
+              when mainnet governance changes cost models.
+
         * Check that SPOs cannot vote on a "protocol parameters update" action that doesn't
           change security parameters
         * Vote to approve the action
@@ -293,7 +300,10 @@ def test_pparam_update(  # noqa: C901
         """
         cluster, governance_data = cluster_lock_governance_plutus
         temp_template = common.get_test_id(cluster)
-        cost_proposal_file = DATA_DIR / "cost_models_list_185_v2_v3.json"
+        cost_proposal_file = cost_model_utils.write_cost_model_proposal(
+            cost_models=cost_model_utils.get_current_cost_models(cluster),
+            dest=temptools.get_basetemp() / f"{temp_template}_cost_models.json",
+        )
         db_errors_final = []
         is_in_bootstrap = conway_common.is_in_bootstrap(cluster_obj=cluster)
 

cardano_node_tests/utils/cost_model_utils.py

@@ -0,0 +1,30 @@
+"""Utilities for cost model proposal generation."""
+
+import json
+import pathlib as pl
+
+from cardano_clusterlib import clusterlib
+
+
+def get_current_cost_models(cluster_obj: clusterlib.ClusterLib) -> dict[str, list[int]]:
+    """Return the current cost models from live protocol parameters."""
+    cost_models: dict[str, list[int]] = cluster_obj.g_query.get_protocol_params()["costModels"]
+    return cost_models
+
+
+def write_cost_model_proposal(
+    cost_models: dict[str, list[int]],
+    dest: pl.Path,
+) -> pl.Path:
+    """Write cost models to a JSON file suitable for --cost-model-file.
+
+    Args:
+        cost_models: Dict mapping Plutus version names to their cost model arrays.
+        dest: Destination path for the JSON file.
+
+    Returns:
+        The destination path.
+    """
+    with open(dest, "w", encoding="utf-8") as fp:
+        json.dump(cost_models, fp, indent=2)
+    return dest

cardano_node_tests/utils/versions.py

@@ -32,7 +32,7 @@ class Versions:
     DEFAULT_CLUSTER_ERA: tp.Final[int] = CONWAY
     DEFAULT_TX_ERA: tp.Final[int] = DEFAULT_CLUSTER_ERA
 
-    # Map protocol versions to era names
+    # Map protocol versions to era names — add new entries here when a new era ships
     MAP: tp.ClassVar[dict[int, str]] = {
         0: "byron",
         1: "byron",
@@ -49,6 +49,9 @@ class Versions:
         12: "dijkstra",
     }
 
+    # Derived from MAP so it stays current when new eras are added above
+    LAST_KNOWN_PROTOCOL_VERSION: tp.Final[int] = max(MAP)
+
     def __init__(self) -> None:
         protocol_version = helpers.get_env_int("PROTOCOL_VERSION", self.DEFAULT_CLUSTER_ERA)
         if protocol_version not in self.MAP: