consensus/misc/4844: fix blob price computation, add test

consensus/misc/eip4844/eip4844.go

@@ -155,7 +155,7 @@ func calcExcessBlobGas(isOsaka bool, bcfg *BlobConfig, parent *types.Header) uin
 		var (
 			baseCost     = big.NewInt(params.BlobBaseCost)
 			reservePrice = baseCost.Mul(baseCost, parent.BaseFee)
-			blobPrice    = bcfg.blobPrice(excessBlobGas)
+			blobPrice    = bcfg.blobPrice(parentExcessBlobGas)
 		)
 		if reservePrice.Cmp(blobPrice) > 0 {
 			scaledExcess := parentBlobGasUsed * uint64(bcfg.Max-bcfg.Target) / uint64(bcfg.Max)

consensus/misc/eip4844/eip4844_test.go

@@ -91,6 +91,65 @@ func TestCalcBlobFee(t *testing.T) {
 	}
 }
 
+func TestCalcBlobFeePostOsaka(t *testing.T) {
+	zero := uint64(0)
+	bpo1 := uint64(1754836608)
+	bpo2 := uint64(1754934912)
+	bpo3 := uint64(1755033216)
+
+	tests := []struct {
+		excessBlobGas uint64
+		blobGasUsed   uint64
+		blobfee       uint64
+		basefee       uint64
+		parenttime    uint64
+		headertime    uint64
+	}{
+		{5149252, 1310720, 5617366, 30, 1754904516, 1754904528},
+		{19251039, 2490368, 20107103, 50, 1755033204, 1755033216},
+	}
+	for i, tt := range tests {
+		config := &params.ChainConfig{
+			LondonBlock: big.NewInt(0),
+			CancunTime:  &zero,
+			PragueTime:  &zero,
+			OsakaTime:   &zero,
+			BPO1Time:    &bpo1,
+			BPO2Time:    &bpo2,
+			BPO3Time:    &bpo3,
+			BlobScheduleConfig: &params.BlobScheduleConfig{
+				Cancun: params.DefaultCancunBlobConfig,
+				Prague: params.DefaultPragueBlobConfig,
+				Osaka:  params.DefaultOsakaBlobConfig,
+				BPO1: &params.BlobConfig{
+					Target:         9,
+					Max:            14,
+					UpdateFraction: 8832827,
+				},
+				BPO2: &params.BlobConfig{
+					Target:         14,
+					Max:            21,
+					UpdateFraction: 13739630,
+				},
+				BPO3: &params.BlobConfig{
+					Target:         21,
+					Max:            32,
+					UpdateFraction: 20609697,
+				},
+			}}
+		parent := &types.Header{
+			ExcessBlobGas: &tt.excessBlobGas,
+			BlobGasUsed:   &tt.blobGasUsed,
+			BaseFee:       big.NewInt(int64(tt.basefee)),
+			Time:          tt.parenttime,
+		}
+		have := CalcExcessBlobGas(config, parent, tt.headertime)
+		if have != tt.blobfee {
+			t.Errorf("test %d: blobfee mismatch: have %v want %v", i, have, tt.blobfee)
+		}
+	}
+}
+
 func TestFakeExponential(t *testing.T) {
 	tests := []struct {
 		factor      int64