fix: add special handling for blob schedule when asserting equal params (#7859)

**Motivation**

Follow up to #7729, we need to
handle blob schedule separately from generic string comparison of
values, otherwise what we compare are shallow stringified arrays. It
does not validate the object properties and on length mismatch we just
get the following error

```
✖ Error: Local and remote configs are different
BLOB_SCHEDULE different value: [object object] != [object object],[object object]
```

**Description**

Add special handling for blob schedule when asserting equal params
- deserialize and sort blob schedules
- compare length of local and remote blob schedule
- then check each entry by comparing `EPOCH` and `MAX_BLOBS_PER_BLOCK`

Author: nflaig

packages/config/src/chainConfig/index.ts

@@ -2,7 +2,7 @@ import {ACTIVE_PRESET} from "@lodestar/params";
 import {defaultChainConfig} from "./default.js";
 import {ChainConfig} from "./types.js";
 
-export {chainConfigToJson, chainConfigFromJson, specValuesToJson} from "./json.js";
+export {chainConfigToJson, chainConfigFromJson, specValuesToJson, deserializeBlobSchedule} from "./json.js";
 export * from "./types.js";
 export * from "./default.js";
 

packages/config/src/chainConfig/json.ts

@@ -1,5 +1,6 @@
 import {fromHex, toHex} from "@lodestar/utils";
 import {
+  BlobSchedule,
   BlobScheduleEntry,
   ChainConfig,
   SpecJson,
@@ -103,45 +104,7 @@ export function serializeSpecValue(
 
 export function deserializeSpecValue(valueStr: unknown, typeName: SpecValueTypeName, keyName: string): SpecValue {
   if (typeName === "blob_schedule") {
-    if (!Array.isArray(valueStr)) {
-      throw Error(`Invalid BLOB_SCHEDULE value ${valueStr} expected array`);
-    }
-
-    const blobSchedule = valueStr.map((entry, i) => {
-      if (typeof entry !== "object" || entry === null) {
-        throw Error(`Invalid BLOB_SCHEDULE[${i}] entry ${entry} expected object`);
-      }
-
-      const out = {} as BlobScheduleEntry;
-
-      for (const key of ["EPOCH", "MAX_BLOBS_PER_BLOCK"] as Array<keyof BlobScheduleEntry>) {
-        const value = entry[key];
-
-        if (value === undefined) {
-          throw Error(`Invalid BLOB_SCHEDULE[${i}] entry ${JSON.stringify(entry)} missing ${key}`);
-        }
-
-        if (typeof value !== "string") {
-          throw Error(`Invalid BLOB_SCHEDULE[${i}].${key} value ${value} expected string`);
-        }
-
-        if (value === MAX_UINT64_JSON) {
-          out[key] = Infinity;
-        } else {
-          const parsed = parseInt(value, 10);
-
-          if (Number.isNaN(parsed)) {
-            throw Error(`Invalid BLOB_SCHEDULE[${i}].${key} value ${value} expected number`);
-          }
-
-          out[key] = parsed;
-        }
-      }
-
-      return out;
-    });
-
-    return blobSchedule;
+    return deserializeBlobSchedule(valueStr);
   }
 
   if (typeof valueStr !== "string") {
@@ -165,3 +128,45 @@ export function deserializeSpecValue(valueStr: unknown, typeName: SpecValueTypeN
       return valueStr;
   }
 }
+
+export function deserializeBlobSchedule(input: unknown): BlobSchedule {
+  if (!Array.isArray(input)) {
+    throw Error(`Invalid BLOB_SCHEDULE value ${input} expected array`);
+  }
+
+  const blobSchedule = input.map((entry, i) => {
+    if (typeof entry !== "object" || entry === null) {
+      throw Error(`Invalid BLOB_SCHEDULE[${i}] entry ${entry} expected object`);
+    }
+
+    const out = {} as BlobScheduleEntry;
+
+    for (const key of ["EPOCH", "MAX_BLOBS_PER_BLOCK"] as Array<keyof BlobScheduleEntry>) {
+      const value = entry[key];
+
+      if (value === undefined) {
+        throw Error(`Invalid BLOB_SCHEDULE[${i}] entry ${JSON.stringify(entry)} missing ${key}`);
+      }
+
+      if (typeof value !== "string") {
+        throw Error(`Invalid BLOB_SCHEDULE[${i}].${key} value ${value} expected string`);
+      }
+
+      if (value === MAX_UINT64_JSON) {
+        out[key] = Infinity;
+      } else {
+        const parsed = parseInt(value, 10);
+
+        if (Number.isNaN(parsed)) {
+          throw Error(`Invalid BLOB_SCHEDULE[${i}].${key} value ${value} expected number`);
+        }
+
+        out[key] = parsed;
+      }
+    }
+
+    return out;
+  });
+
+  return blobSchedule;
+}

packages/validator/src/util/params.ts

@@ -1,4 +1,4 @@
-import {ChainConfig, SpecJson, chainConfigToJson} from "@lodestar/config";
+import {BlobScheduleEntry, ChainConfig, SpecJson, chainConfigToJson, deserializeBlobSchedule} from "@lodestar/config";
 import {BeaconPreset, activePreset, presetToJson} from "@lodestar/params";
 
 export class NotEqualParamsError extends Error {}
@@ -52,6 +52,35 @@ export function assertEqualParams(localConfig: ChainConfig, externalSpecJson: Sp
       continue;
     }
 
+    if (key === "BLOB_SCHEDULE") {
+      const localBlobSchedule = deserializeBlobSchedule(localSpecJson[key]).sort((a, b) => a.EPOCH - b.EPOCH);
+      const remoteBlobSchedule = deserializeBlobSchedule(externalSpecJson[key]).sort((a, b) => a.EPOCH - b.EPOCH);
+
+      if (localBlobSchedule.length !== remoteBlobSchedule.length) {
+        errors.push(`BLOB_SCHEDULE different length: ${localBlobSchedule.length} != ${remoteBlobSchedule.length}`);
+
+        // Skip per entry comparison
+        continue;
+      }
+
+      for (let i = 0; i < localBlobSchedule.length; i++) {
+        const localEntry = localBlobSchedule[i];
+        const remoteEntry = remoteBlobSchedule[i];
+
+        for (const entryKey of ["EPOCH", "MAX_BLOBS_PER_BLOCK"] as Array<keyof BlobScheduleEntry>) {
+          const localValue = String(localEntry[entryKey]);
+          const remoteValue = String(remoteEntry[entryKey]);
+
+          if (localValue !== remoteValue) {
+            errors.push(`BLOB_SCHEDULE[${i}].${entryKey} different value: ${localValue} != ${remoteValue}`);
+          }
+        }
+      }
+
+      // Skip generic string comparison
+      continue;
+    }
+
     // Must compare JSON serialized specs, to ensure all strings are rendered in the same way
     // Must compare as lowercase to ensure checksum addresses and names have same capilatization
     const localValue = String(localSpecJson[key]).toLocaleLowerCase();