[FeeHistory] Allow test chains with few blocks (#699)

The (gas)controller requests 20.000 long range results when opening the FeeMarket.
New chains / test chains normally don't have that amount of blocks, and in this case the controller requests feeHistory with a wrong hex value (0x-4756) which pollutes the node logs.

Beside this such a chain can return fewer results than requested, the current code doesn't handle this case correctly when analyzing feeHistory results. This leads to fallback to eth_gas mode.

FIXED: (Gas)Controller does not detect FeeMarket mode for test chains, even the chain supports EIP1559.

src/gas/fetchBlockFeeHistory.test.ts

@@ -389,4 +389,37 @@ describe('fetchBlockFeeHistory', () => {
       ]);
     });
   });
+
+  describe('given a range which exceeds existing blocks', () => {
+    beforeEach(() => {
+      jest.resetAllMocks();
+    });
+
+    it('should adjust fetched numberOfBlocks', async () => {
+      const latestBlockNumber = 1024;
+      const numberOfRequestedBlocks = 2048;
+      const endBlock = new BN(latestBlockNumber);
+
+      when(mockedQuery)
+        .calledWith(ethQuery, 'eth_feeHistory', [
+          toHex(latestBlockNumber),
+          toHex(latestBlockNumber),
+          [],
+        ])
+        .mockResolvedValue({
+          oldestBlock: toHex(0),
+          baseFeePerGas: [],
+          gasUsedRatio: [],
+          reward: [],
+        });
+
+      await fetchBlockFeeHistory({
+        ethQuery,
+        numberOfBlocks: numberOfRequestedBlocks,
+        endBlock,
+      });
+
+      expect(mockedQuery).toHaveBeenCalledTimes(1);
+    });
+  });
 });

src/gas/fetchBlockFeeHistory.ts

@@ -304,12 +304,14 @@ async function makeRequestForChunk<Percentile extends number>({
       : response.baseFeePerGas.slice(0, numberOfBlocks);
     const gasUsedRatios = response.gasUsedRatio;
     const priorityFeePercentileGroups = response.reward ?? [];
+    // Chain is allowed to return fewer number of block results
+    const numberOfExistingResults = gasUsedRatios.length;
 
     return baseFeesPerGasAsHex.map((baseFeePerGasAsHex, blockIndex) => {
       const baseFeePerGas = fromHex(baseFeePerGasAsHex);
       const number = startBlockNumber.addn(blockIndex);
 
-      return blockIndex > numberOfBlocks - 1
+      return blockIndex >= numberOfExistingResults
         ? buildNextFeeHistoryBlock({ baseFeePerGas, number })
         : buildExistingFeeHistoryBlock({
             baseFeePerGas,
@@ -329,6 +331,9 @@ async function makeRequestForChunk<Percentile extends number>({
  * Divides a block range (specified by a range size and the end of the range) into chunks based on
  * the maximum number of blocks that `eth_feeHistory` can return in a single call.
  *
+ * If the requested totalNumberOfBlocks exceed endBlockNumber, totalNumberOfBlocks is
+ * truncated to avoid requesting chunks with negative endBlockNumber.
+ *
  * @param endBlockNumber - The final block in the complete desired block range after all
  * `eth_feeHistory` requests have been made.
  * @param totalNumberOfBlocks - The total number of desired blocks after all `eth_feeHistory`
@@ -340,6 +345,10 @@ function determineRequestChunkSpecifiers(
   endBlockNumber: BN,
   totalNumberOfBlocks: number,
 ): RequestChunkSpecifier[] {
+  if (endBlockNumber.lt(new BN(totalNumberOfBlocks))) {
+    totalNumberOfBlocks = endBlockNumber.toNumber();
+  }
+
   const specifiers = [];
   for (
     let chunkStartBlockNumber = endBlockNumber.subn(totalNumberOfBlocks);