Double sign unit test (#2955)

* [test] added schedule for sharding

* [test] refactored double_sign_test.go

* [test] comment out all test cases for now.

* [test] added record Copy method for testing

* [test] added the first test case in TestVerify

* [test] finished test TestVerify

* [test] Added test TestVerify, TestApplySlashRate, TestSetDifference

* [test] half through TestDelegatorSlashApply

* [test] fix the problem cause by unsafe usage of big.Int

* [staking] added the copy methods to validatorWrapper

* [test] added test cases for copy method for staking/validatorWrapper

* [test] added test case TestApply

* [test] added test case TestRate

* [test] fix the golint errors

* [test] removed commented out unit test code

* [test] remote the empty line in imports

* [test] moved copy methods to stake_testing module

* [test] removed usage of interface stateDB

* [test] removed empty lines in imports

* [test] fixed golint package name issues

* [test] removed a todo when writing code

* [test] moved record.Copy to staking/slash/test

internal/configs/sharding/testnet.go

@@ -3,10 +3,9 @@ package shardingconfig
 import (
 	"math/big"
 
-	"github.com/harmony-one/harmony/numeric"
-
 	"github.com/harmony-one/harmony/internal/genesis"
 	"github.com/harmony-one/harmony/internal/params"
+	"github.com/harmony-one/harmony/numeric"
 )
 
 // TestnetSchedule is the long-running public testnet sharding

staking/slash/double-sign.go

@@ -11,10 +11,8 @@ import (
 	consensus_sig "github.com/harmony-one/harmony/consensus/signature"
 	"github.com/harmony-one/harmony/consensus/votepower"
 	"github.com/harmony-one/harmony/core/state"
-	"github.com/harmony-one/harmony/core/types"
 	"github.com/harmony-one/harmony/crypto/hash"
 	common2 "github.com/harmony-one/harmony/internal/common"
-	"github.com/harmony-one/harmony/internal/params"
 	"github.com/harmony-one/harmony/internal/utils"
 	"github.com/harmony-one/harmony/numeric"
 	"github.com/harmony-one/harmony/shard"
@@ -143,13 +141,6 @@ func (r Record) String() string {
 	return string(s)
 }
 
-// CommitteeReader ..
-type CommitteeReader interface {
-	Config() *params.ChainConfig
-	ReadShardState(epoch *big.Int) (*shard.State, error)
-	CurrentBlock() *types.Block
-}
-
 // Verify checks that the slash is valid
 func Verify(
 	chain CommitteeReader,