core: remove dead code, limit test code scope (#17006)

* core: move test util var/func to test file

* core: remove useless func

core/blockchain_test.go

@@ -25,6 +25,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/consensus"
 	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/core/state"
@@ -35,6 +36,39 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
+// So we can deterministically seed different blockchains
+var (
+	canonicalSeed = 1
+	forkSeed      = 2
+)
+
+// newCanonical creates a chain database, and injects a deterministic canonical
+// chain. Depending on the full flag, if creates either a full block chain or a
+// header only chain.
+func newCanonical(engine consensus.Engine, n int, full bool) (ethdb.Database, *BlockChain, error) {
+	var (
+		db      = ethdb.NewMemDatabase()
+		genesis = new(Genesis).MustCommit(db)
+	)
+
+	// Initialize a fresh chain with only a genesis block
+	blockchain, _ := NewBlockChain(db, nil, params.AllEthashProtocolChanges, engine, vm.Config{})
+	// Create and inject the requested chain
+	if n == 0 {
+		return db, blockchain, nil
+	}
+	if full {
+		// Full block-chain requested
+		blocks := makeBlockChain(genesis, n, engine, db, canonicalSeed)
+		_, err := blockchain.InsertChain(blocks)
+		return db, blockchain, err
+	}
+	// Header-only chain requested
+	headers := makeHeaderChain(genesis.Header(), n, engine, db, canonicalSeed)
+	_, err := blockchain.InsertHeaderChain(headers, 1)
+	return db, blockchain, err
+}
+
 // Test fork of length N starting from block i
 func testFork(t *testing.T, blockchain *BlockChain, i, n int, full bool, comparator func(td1, td2 *big.Int)) {
 	// Copy old chain up to #i into a new db