tests: add ethash difficulty tests (#15191)

tests/difficulty_test_util.go

@@ -0,0 +1,70 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+//
+
+package tests
+
+import (
+	"fmt"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/math"
+	"github.com/ethereum/go-ethereum/consensus/ethash"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+//go:generate gencodec -type DifficultyTest -field-override difficultyTestMarshaling -out gen_difficultytest.go
+
+type DifficultyTest struct {
+	ParentTimestamp    *big.Int    `json:"parentTimestamp"`
+	ParentDifficulty   *big.Int    `json:"parentDifficulty"`
+	UncleHash          common.Hash `json:"parentUncles"`
+	CurrentTimestamp   *big.Int    `json:"currentTimestamp"`
+	CurrentBlockNumber uint64      `json:"currentBlockNumber"`
+	CurrentDifficulty  *big.Int    `json:"currentDifficulty"`
+}
+
+type difficultyTestMarshaling struct {
+	ParentTimestamp    *math.HexOrDecimal256
+	ParentDifficulty   *math.HexOrDecimal256
+	CurrentTimestamp   *math.HexOrDecimal256
+	CurrentDifficulty  *math.HexOrDecimal256
+	UncleHash          common.Hash
+	CurrentBlockNumber math.HexOrDecimal64
+}
+
+func (test *DifficultyTest) Run(config *params.ChainConfig) error {
+	parentNumber := big.NewInt(int64(test.CurrentBlockNumber - 1))
+	parent := &types.Header{
+		Difficulty: test.ParentDifficulty,
+		Time:       test.ParentTimestamp,
+		Number:     parentNumber,
+		UncleHash:  test.UncleHash,
+	}
+
+	actual := ethash.CalcDifficulty(config, test.CurrentTimestamp.Uint64(), parent)
+	exp := test.CurrentDifficulty
+
+	if actual.Cmp(exp) != 0 {
+		return fmt.Errorf("parent[time %v diff %v unclehash:%x] child[time %v number %v] diff %v != expected %v",
+			test.ParentTimestamp, test.ParentDifficulty, test.UncleHash,
+			test.CurrentTimestamp, test.CurrentBlockNumber, actual, exp)
+	}
+	return nil
+
+}