diff --git a/e2e_test/.gitignore b/e2e_test/.gitignore
new file mode 100644
index 0000000000..1e4ded714a
--- /dev/null
+++ b/e2e_test/.gitignore
@@ -0,0 +1,2 @@
+cache
+out
diff --git a/e2e_test/contracts/GoldToken.sol b/e2e_test/contracts/GoldToken.sol
new file mode 100644
index 0000000000..8b31cad522
--- /dev/null
+++ b/e2e_test/contracts/GoldToken.sol
@@ -0,0 +1,1147 @@
+pragma solidity ^0.5.13;
+
+/*
+ * @dev Provides information about the current execution context, including the
+ * sender of the transaction and its data. While these are generally available
+ * via msg.sender and msg.data, they should not be accessed in such a direct
+ * manner, since when dealing with GSN meta-transactions the account sending and
+ * paying for execution may not be the actual sender (as far as an application
+ * is concerned).
+ *
+ * This contract is only required for intermediate, library-like contracts.
+ */
+contract Context {
+    // Empty internal constructor, to prevent people from mistakenly deploying
+    // an instance of this contract, which should be used via inheritance.
+    constructor () internal { }
+    // solhint-disable-previous-line no-empty-blocks
+
+    function _msgSender() internal view returns (address payable) {
+        return msg.sender;
+    }
+
+    function _msgData() internal view returns (bytes memory) {
+        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
+        return msg.data;
+    }
+}
+
+/**
+ * @dev Contract module which provides a basic access control mechanism, where
+ * there is an account (an owner) that can be granted exclusive access to
+ * specific functions.
+ *
+ * This module is used through inheritance. It will make available the modifier
+ * `onlyOwner`, which can be applied to your functions to restrict their use to
+ * the owner.
+ */
+contract Ownable is Context {
+    address private _owner;
+
+    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
+
+    /**
+     * @dev Initializes the contract setting the deployer as the initial owner.
+     */
+    constructor () internal {
+        address msgSender = _msgSender();
+        _owner = msgSender;
+        emit OwnershipTransferred(address(0), msgSender);
+    }
+
+    /**
+     * @dev Returns the address of the current owner.
+     */
+    function owner() public view returns (address) {
+        return _owner;
+    }
+
+    /**
+     * @dev Throws if called by any account other than the owner.
+     */
+    modifier onlyOwner() {
+        require(isOwner(), "Ownable: caller is not the owner");
+        _;
+    }
+
+    /**
+     * @dev Returns true if the caller is the current owner.
+     */
+    function isOwner() public view returns (bool) {
+        return _msgSender() == _owner;
+    }
+
+    /**
+     * @dev Leaves the contract without owner. It will not be possible to call
+     * `onlyOwner` functions anymore. Can only be called by the current owner.
+     *
+     * NOTE: Renouncing ownership will leave the contract without an owner,
+     * thereby removing any functionality that is only available to the owner.
+     */
+    function renounceOwnership() public onlyOwner {
+        emit OwnershipTransferred(_owner, address(0));
+        _owner = address(0);
+    }
+
+    /**
+     * @dev Transfers ownership of the contract to a new account (`newOwner`).
+     * Can only be called by the current owner.
+     */
+    function transferOwnership(address newOwner) public onlyOwner {
+        _transferOwnership(newOwner);
+    }
+
+    /**
+     * @dev Transfers ownership of the contract to a new account (`newOwner`).
+     */
+    function _transferOwnership(address newOwner) internal {
+        require(newOwner != address(0), "Ownable: new owner is the zero address");
+        emit OwnershipTransferred(_owner, newOwner);
+        _owner = newOwner;
+    }
+}
+
+/**
+ * @dev Wrappers over Solidity's arithmetic operations with added overflow
+ * checks.
+ *
+ * Arithmetic operations in Solidity wrap on overflow. This can easily result
+ * in bugs, because programmers usually assume that an overflow raises an
+ * error, which is the standard behavior in high level programming languages.
+ * `SafeMath` restores this intuition by reverting the transaction when an
+ * operation overflows.
+ *
+ * Using this library instead of the unchecked operations eliminates an entire
+ * class of bugs, so it's recommended to use it always.
+ */
+library SafeMath {
+    /**
+     * @dev Returns the addition of two unsigned integers, reverting on
+     * overflow.
+     *
+     * Counterpart to Solidity's `+` operator.
+     *
+     * Requirements:
+     * - Addition cannot overflow.
+     */
+    function add(uint256 a, uint256 b) internal pure returns (uint256) {
+        uint256 c = a + b;
+        require(c >= a, "SafeMath: addition overflow");
+
+        return c;
+    }
+
+    /**
+     * @dev Returns the subtraction of two unsigned integers, reverting on
+     * overflow (when the result is negative).
+     *
+     * Counterpart to Solidity's `-` operator.
+     *
+     * Requirements:
+     * - Subtraction cannot overflow.
+     */
+    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
+        return sub(a, b, "SafeMath: subtraction overflow");
+    }
+
+    /**
+     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
+     * overflow (when the result is negative).
+     *
+     * Counterpart to Solidity's `-` operator.
+     *
+     * Requirements:
+     * - Subtraction cannot overflow.
+     *
+     * _Available since v2.4.0._
+     */
+    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
+        require(b <= a, errorMessage);
+        uint256 c = a - b;
+
+        return c;
+    }
+
+    /**
+     * @dev Returns the multiplication of two unsigned integers, reverting on
+     * overflow.
+     *
+     * Counterpart to Solidity's `*` operator.
+     *
+     * Requirements:
+     * - Multiplication cannot overflow.
+     */
+    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
+        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
+        // benefit is lost if 'b' is also tested.
+        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
+        if (a == 0) {
+            return 0;
+        }
+
+        uint256 c = a * b;
+        require(c / a == b, "SafeMath: multiplication overflow");
+
+        return c;
+    }
+
+    /**
+     * @dev Returns the integer division of two unsigned integers. Reverts on
+     * division by zero. The result is rounded towards zero.
+     *
+     * Counterpart to Solidity's `/` operator. Note: this function uses a
+     * `revert` opcode (which leaves remaining gas untouched) while Solidity
+     * uses an invalid opcode to revert (consuming all remaining gas).
+     *
+     * Requirements:
+     * - The divisor cannot be zero.
+     */
+    function div(uint256 a, uint256 b) internal pure returns (uint256) {
+        return div(a, b, "SafeMath: division by zero");
+    }
+
+    /**
+     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
+     * division by zero. The result is rounded towards zero.
+     *
+     * Counterpart to Solidity's `/` operator. Note: this function uses a
+     * `revert` opcode (which leaves remaining gas untouched) while Solidity
+     * uses an invalid opcode to revert (consuming all remaining gas).
+     *
+     * Requirements:
+     * - The divisor cannot be zero.
+     *
+     * _Available since v2.4.0._
+     */
+    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
+        // Solidity only automatically asserts when dividing by 0
+        require(b > 0, errorMessage);
+        uint256 c = a / b;
+        // assert(a == b * c + a % b); // There is no case in which this doesn't hold
+
+        return c;
+    }
+
+    /**
+     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
+     * Reverts when dividing by zero.
+     *
+     * Counterpart to Solidity's `%` operator. This function uses a `revert`
+     * opcode (which leaves remaining gas untouched) while Solidity uses an
+     * invalid opcode to revert (consuming all remaining gas).
+     *
+     * Requirements:
+     * - The divisor cannot be zero.
+     */
+    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
+        return mod(a, b, "SafeMath: modulo by zero");
+    }
+
+    /**
+     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
+     * Reverts with custom message when dividing by zero.
+     *
+     * Counterpart to Solidity's `%` operator. This function uses a `revert`
+     * opcode (which leaves remaining gas untouched) while Solidity uses an
+     * invalid opcode to revert (consuming all remaining gas).
+     *
+     * Requirements:
+     * - The divisor cannot be zero.
+     *
+     * _Available since v2.4.0._
+     */
+    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
+        require(b != 0, errorMessage);
+        return a % b;
+    }
+}
+
+/**
+ * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
+ * the optional functions; to access them see {ERC20Detailed}.
+ */
+interface IERC20 {
+    /**
+     * @dev Returns the amount of tokens in existence.
+     */
+    function totalSupply() external view returns (uint256);
+
+    /**
+     * @dev Returns the amount of tokens owned by `account`.
+     */
+    function balanceOf(address account) external view returns (uint256);
+
+    /**
+     * @dev Moves `amount` tokens from the caller's account to `recipient`.
+     *
+     * Returns a boolean value indicating whether the operation succeeded.
+     *
+     * Emits a {Transfer} event.
+     */
+    function transfer(address recipient, uint256 amount) external returns (bool);
+
+    /**
+     * @dev Returns the remaining number of tokens that `spender` will be
+     * allowed to spend on behalf of `owner` through {transferFrom}. This is
+     * zero by default.
+     *
+     * This value changes when {approve} or {transferFrom} are called.
+     */
+    function allowance(address owner, address spender) external view returns (uint256);
+
+    /**
+     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
+     *
+     * Returns a boolean value indicating whether the operation succeeded.
+     *
+     * IMPORTANT: Beware that changing an allowance with this method brings the risk
+     * that someone may use both the old and the new allowance by unfortunate
+     * transaction ordering. One possible solution to mitigate this race
+     * condition is to first reduce the spender's allowance to 0 and set the
+     * desired value afterwards:
+     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
+     *
+     * Emits an {Approval} event.
+     */
+    function approve(address spender, uint256 amount) external returns (bool);
+
+    /**
+     * @dev Moves `amount` tokens from `sender` to `recipient` using the
+     * allowance mechanism. `amount` is then deducted from the caller's
+     * allowance.
+     *
+     * Returns a boolean value indicating whether the operation succeeded.
+     *
+     * Emits a {Transfer} event.
+     */
+    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
+
+    /**
+     * @dev Emitted when `value` tokens are moved from one account (`from`) to
+     * another (`to`).
+     *
+     * Note that `value` may be zero.
+     */
+    event Transfer(address indexed from, address indexed to, uint256 value);
+
+    /**
+     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
+     * a call to {approve}. `value` is the new allowance.
+     */
+    event Approval(address indexed owner, address indexed spender, uint256 value);
+}
+
+interface IAccounts {
+  function isAccount(address) external view returns (bool);
+  function voteSignerToAccount(address) external view returns (address);
+  function validatorSignerToAccount(address) external view returns (address);
+  function attestationSignerToAccount(address) external view returns (address);
+  function signerToAccount(address) external view returns (address);
+  function getAttestationSigner(address) external view returns (address);
+  function getValidatorSigner(address) external view returns (address);
+  function getVoteSigner(address) external view returns (address);
+  function hasAuthorizedVoteSigner(address) external view returns (bool);
+  function hasAuthorizedValidatorSigner(address) external view returns (bool);
+  function hasAuthorizedAttestationSigner(address) external view returns (bool);
+
+  function setAccountDataEncryptionKey(bytes calldata) external;
+  function setMetadataURL(string calldata) external;
+  function setName(string calldata) external;
+  function setWalletAddress(address, uint8, bytes32, bytes32) external;
+  function setAccount(string calldata, bytes calldata, address, uint8, bytes32, bytes32) external;
+
+  function getDataEncryptionKey(address) external view returns (bytes memory);
+  function getWalletAddress(address) external view returns (address);
+  function getMetadataURL(address) external view returns (string memory);
+  function batchGetMetadataURL(address[] calldata)
+    external
+    view
+    returns (uint256[] memory, bytes memory);
+  function getName(address) external view returns (string memory);
+
+  function authorizeVoteSigner(address, uint8, bytes32, bytes32) external;
+  function authorizeValidatorSigner(address, uint8, bytes32, bytes32) external;
+  function authorizeValidatorSignerWithPublicKey(address, uint8, bytes32, bytes32, bytes calldata)
+    external;
+  function authorizeValidatorSignerWithKeys(
+    address,
+    uint8,
+    bytes32,
+    bytes32,
+    bytes calldata,
+    bytes calldata,
+    bytes calldata
+  ) external;
+  function authorizeAttestationSigner(address, uint8, bytes32, bytes32) external;
+  function createAccount() external returns (bool);
+
+  function setPaymentDelegation(address, uint256) external;
+  function getPaymentDelegation(address) external view returns (address, uint256);
+  function isSigner(address, address, bytes32) external view returns (bool);
+}
+
+interface IFeeCurrencyWhitelist {
+  function addToken(address) external;
+  function getWhitelist() external view returns (address[] memory);
+}
+
+interface IFreezer {
+  function isFrozen(address) external view returns (bool);
+}
+
+interface IRegistry {
+  function setAddressFor(string calldata, address) external;
+  function getAddressForOrDie(bytes32) external view returns (address);
+  function getAddressFor(bytes32) external view returns (address);
+  function getAddressForStringOrDie(string calldata identifier) external view returns (address);
+  function getAddressForString(string calldata identifier) external view returns (address);
+  function isOneOf(bytes32[] calldata, address) external view returns (bool);
+}
+
+interface IElection {
+  function electValidatorSigners() external view returns (address[] memory);
+  function electNValidatorSigners(uint256, uint256) external view returns (address[] memory);
+  function vote(address, uint256, address, address) external returns (bool);
+  function activate(address) external returns (bool);
+  function revokeActive(address, uint256, address, address, uint256) external returns (bool);
+  function revokeAllActive(address, address, address, uint256) external returns (bool);
+  function revokePending(address, uint256, address, address, uint256) external returns (bool);
+  function markGroupIneligible(address) external;
+  function markGroupEligible(address, address, address) external;
+  function allowedToVoteOverMaxNumberOfGroups(address) external returns (bool);
+  function forceDecrementVotes(
+    address,
+    uint256,
+    address[] calldata,
+    address[] calldata,
+    uint256[] calldata
+  ) external returns (uint256);
+
+  // view functions
+  function getElectableValidators() external view returns (uint256, uint256);
+  function getElectabilityThreshold() external view returns (uint256);
+  function getNumVotesReceivable(address) external view returns (uint256);
+  function getTotalVotes() external view returns (uint256);
+  function getActiveVotes() external view returns (uint256);
+  function getTotalVotesByAccount(address) external view returns (uint256);
+  function getPendingVotesForGroupByAccount(address, address) external view returns (uint256);
+  function getActiveVotesForGroupByAccount(address, address) external view returns (uint256);
+  function getTotalVotesForGroupByAccount(address, address) external view returns (uint256);
+  function getActiveVoteUnitsForGroupByAccount(address, address) external view returns (uint256);
+  function getTotalVotesForGroup(address) external view returns (uint256);
+  function getActiveVotesForGroup(address) external view returns (uint256);
+  function getPendingVotesForGroup(address) external view returns (uint256);
+  function getGroupEligibility(address) external view returns (bool);
+  function getGroupEpochRewards(address, uint256, uint256[] calldata)
+    external
+    view
+    returns (uint256);
+  function getGroupsVotedForByAccount(address) external view returns (address[] memory);
+  function getEligibleValidatorGroups() external view returns (address[] memory);
+  function getTotalVotesForEligibleValidatorGroups()
+    external
+    view
+    returns (address[] memory, uint256[] memory);
+  function getCurrentValidatorSigners() external view returns (address[] memory);
+  function canReceiveVotes(address, uint256) external view returns (bool);
+  function hasActivatablePendingVotes(address, address) external view returns (bool);
+
+  // only owner
+  function setElectableValidators(uint256, uint256) external returns (bool);
+  function setMaxNumGroupsVotedFor(uint256) external returns (bool);
+  function setElectabilityThreshold(uint256) external returns (bool);
+
+  // only VM
+  function distributeEpochRewards(address, uint256, address, address) external;
+}
+
+interface IGovernance {
+  function isVoting(address) external view returns (bool);
+  function getAmountOfGoldUsedForVoting(address account) external view returns (uint256);
+}
+
+interface ILockedGold {
+  function incrementNonvotingAccountBalance(address, uint256) external;
+  function decrementNonvotingAccountBalance(address, uint256) external;
+  function getAccountTotalLockedGold(address) external view returns (uint256);
+  function getTotalLockedGold() external view returns (uint256);
+  function getPendingWithdrawals(address)
+    external
+    view
+    returns (uint256[] memory, uint256[] memory);
+  function getTotalPendingWithdrawals(address) external view returns (uint256);
+  function lock() external payable;
+  function unlock(uint256) external;
+  function relock(uint256, uint256) external;
+  function withdraw(uint256) external;
+  function slash(
+    address account,
+    uint256 penalty,
+    address reporter,
+    uint256 reward,
+    address[] calldata lessers,
+    address[] calldata greaters,
+    uint256[] calldata indices
+  ) external;
+  function isSlasher(address) external view returns (bool);
+}
+
+interface IValidators {
+  function registerValidator(bytes calldata, bytes calldata, bytes calldata)
+    external
+    returns (bool);
+  function deregisterValidator(uint256) external returns (bool);
+  function affiliate(address) external returns (bool);
+  function deaffiliate() external returns (bool);
+  function updateBlsPublicKey(bytes calldata, bytes calldata) external returns (bool);
+  function registerValidatorGroup(uint256) external returns (bool);
+  function deregisterValidatorGroup(uint256) external returns (bool);
+  function addMember(address) external returns (bool);
+  function addFirstMember(address, address, address) external returns (bool);
+  function removeMember(address) external returns (bool);
+  function reorderMember(address, address, address) external returns (bool);
+  function updateCommission() external;
+  function setNextCommissionUpdate(uint256) external;
+  function resetSlashingMultiplier() external;
+
+  // only owner
+  function setCommissionUpdateDelay(uint256) external;
+  function setMaxGroupSize(uint256) external returns (bool);
+  function setMembershipHistoryLength(uint256) external returns (bool);
+  function setValidatorScoreParameters(uint256, uint256) external returns (bool);
+  function setGroupLockedGoldRequirements(uint256, uint256) external returns (bool);
+  function setValidatorLockedGoldRequirements(uint256, uint256) external returns (bool);
+  function setSlashingMultiplierResetPeriod(uint256) external;
+
+  // view functions
+  function getMaxGroupSize() external view returns (uint256);
+  function getCommissionUpdateDelay() external view returns (uint256);
+  function getValidatorScoreParameters() external view returns (uint256, uint256);
+  function getMembershipHistory(address)
+    external
+    view
+    returns (uint256[] memory, address[] memory, uint256, uint256);
+  function calculateEpochScore(uint256) external view returns (uint256);
+  function calculateGroupEpochScore(uint256[] calldata) external view returns (uint256);
+  function getAccountLockedGoldRequirement(address) external view returns (uint256);
+  function meetsAccountLockedGoldRequirements(address) external view returns (bool);
+  function getValidatorBlsPublicKeyFromSigner(address) external view returns (bytes memory);
+  function getValidator(address account)
+    external
+    view
+    returns (bytes memory, bytes memory, address, uint256, address);
+  function getValidatorGroup(address)
+    external
+    view
+    returns (address[] memory, uint256, uint256, uint256, uint256[] memory, uint256, uint256);
+  function getGroupNumMembers(address) external view returns (uint256);
+  function getTopGroupValidators(address, uint256) external view returns (address[] memory);
+  function getGroupsNumMembers(address[] calldata accounts)
+    external
+    view
+    returns (uint256[] memory);
+  function getNumRegisteredValidators() external view returns (uint256);
+  function groupMembershipInEpoch(address, uint256, uint256) external view returns (address);
+
+  // only registered contract
+  function updateEcdsaPublicKey(address, address, bytes calldata) external returns (bool);
+  function updatePublicKeys(address, address, bytes calldata, bytes calldata, bytes calldata)
+    external
+    returns (bool);
+  function getValidatorLockedGoldRequirements() external view returns (uint256, uint256);
+  function getGroupLockedGoldRequirements() external view returns (uint256, uint256);
+  function getRegisteredValidators() external view returns (address[] memory);
+  function getRegisteredValidatorSigners() external view returns (address[] memory);
+  function getRegisteredValidatorGroups() external view returns (address[] memory);
+  function isValidatorGroup(address) external view returns (bool);
+  function isValidator(address) external view returns (bool);
+  function getValidatorGroupSlashingMultiplier(address) external view returns (uint256);
+  function getMembershipInLastEpoch(address) external view returns (address);
+  function getMembershipInLastEpochFromSigner(address) external view returns (address);
+
+  // only VM
+  function updateValidatorScoreFromSigner(address, uint256) external;
+  function distributeEpochPaymentsFromSigner(address, uint256) external returns (uint256);
+
+  // only slasher
+  function forceDeaffiliateIfValidator(address) external;
+  function halveSlashingMultiplier(address) external;
+
+}
+
+interface IRandom {
+  function revealAndCommit(bytes32, bytes32, address) external;
+  function randomnessBlockRetentionWindow() external view returns (uint256);
+  function random() external view returns (bytes32);
+  function getBlockRandomness(uint256) external view returns (bytes32);
+}
+
+interface IAttestations {
+  function revoke(bytes32, uint256) external;
+  function withdraw(address) external;
+
+  // view functions
+  function getUnselectedRequest(bytes32, address) external view returns (uint32, uint32, address);
+  function getAttestationIssuers(bytes32, address) external view returns (address[] memory);
+  function getAttestationStats(bytes32, address) external view returns (uint32, uint32);
+  function batchGetAttestationStats(bytes32[] calldata)
+    external
+    view
+    returns (uint256[] memory, address[] memory, uint64[] memory, uint64[] memory);
+  function getAttestationState(bytes32, address, address)
+    external
+    view
+    returns (uint8, uint32, address);
+  function getCompletableAttestations(bytes32, address)
+    external
+    view
+    returns (uint32[] memory, address[] memory, uint256[] memory, bytes memory);
+  function getAttestationRequestFee(address) external view returns (uint256);
+  function getMaxAttestations() external view returns (uint256);
+  function validateAttestationCode(bytes32, address, uint8, bytes32, bytes32)
+    external
+    view
+    returns (address);
+  function lookupAccountsForIdentifier(bytes32) external view returns (address[] memory);
+  function requireNAttestationsRequested(bytes32, address, uint32) external view;
+
+  // only owner
+  function setAttestationRequestFee(address, uint256) external;
+  function setAttestationExpiryBlocks(uint256) external;
+  function setSelectIssuersWaitBlocks(uint256) external;
+  function setMaxAttestations(uint256) external;
+}
+
+interface IExchange {
+    function buy(
+        uint256,
+        uint256,
+        bool
+    ) external returns (uint256);
+
+    function sell(
+        uint256,
+        uint256,
+        bool
+    ) external returns (uint256);
+
+    function exchange(
+        uint256,
+        uint256,
+        bool
+    ) external returns (uint256);
+
+    function setUpdateFrequency(uint256) external;
+
+    function getBuyTokenAmount(uint256, bool) external view returns (uint256);
+
+    function getSellTokenAmount(uint256, bool) external view returns (uint256);
+
+    function getBuyAndSellBuckets(bool) external view returns (uint256, uint256);
+}
+
+interface IReserve {
+    function setTobinTaxStalenessThreshold(uint256) external;
+
+    function addToken(address) external returns (bool);
+
+    function removeToken(address, uint256) external returns (bool);
+
+    function transferGold(address payable, uint256) external returns (bool);
+
+    function transferExchangeGold(address payable, uint256) external returns (bool);
+
+    function getReserveGoldBalance() external view returns (uint256);
+
+    function getUnfrozenReserveGoldBalance() external view returns (uint256);
+
+    function getOrComputeTobinTax() external returns (uint256, uint256);
+
+    function getTokens() external view returns (address[] memory);
+
+    function getReserveRatio() external view returns (uint256);
+
+    function addExchangeSpender(address) external;
+
+    function removeExchangeSpender(address, uint256) external;
+
+    function addSpender(address) external;
+
+    function removeSpender(address) external;
+}
+
+/**
+ * @title This interface describes the functions specific to Celo Stable Tokens, and in the
+ * absence of interface inheritance is intended as a companion to IERC20.sol and ICeloToken.sol.
+ */
+interface IStableToken {
+    function mint(address, uint256) external returns (bool);
+
+    function burn(uint256) external returns (bool);
+
+    function setInflationParameters(uint256, uint256) external;
+
+    function valueToUnits(uint256) external view returns (uint256);
+
+    function unitsToValue(uint256) external view returns (uint256);
+
+    function getInflationParameters()
+        external
+        view
+        returns (
+            uint256,
+            uint256,
+            uint256,
+            uint256
+        );
+
+    // NOTE: duplicated with IERC20.sol, remove once interface inheritance is supported.
+    function balanceOf(address) external view returns (uint256);
+}
+
+interface ISortedOracles {
+  function addOracle(address, address) external;
+  function removeOracle(address, address, uint256) external;
+  function report(address, uint256, address, address) external;
+  function removeExpiredReports(address, uint256) external;
+  function isOldestReportExpired(address token) external view returns (bool, address);
+  function numRates(address) external view returns (uint256);
+  function medianRate(address) external view returns (uint256, uint256);
+  function numTimestamps(address) external view returns (uint256);
+  function medianTimestamp(address) external view returns (uint256);
+}
+
+contract UsingRegistry is Ownable {
+  event RegistrySet(address indexed registryAddress);
+
+  // solhint-disable state-visibility
+  bytes32 constant ACCOUNTS_REGISTRY_ID = keccak256(abi.encodePacked("Accounts"));
+  bytes32 constant ATTESTATIONS_REGISTRY_ID = keccak256(abi.encodePacked("Attestations"));
+  bytes32 constant DOWNTIME_SLASHER_REGISTRY_ID = keccak256(abi.encodePacked("DowntimeSlasher"));
+  bytes32 constant DOUBLE_SIGNING_SLASHER_REGISTRY_ID = keccak256(
+    abi.encodePacked("DoubleSigningSlasher")
+  );
+  bytes32 constant ELECTION_REGISTRY_ID = keccak256(abi.encodePacked("Election"));
+  bytes32 constant EXCHANGE_REGISTRY_ID = keccak256(abi.encodePacked("Exchange"));
+  bytes32 constant FEE_CURRENCY_WHITELIST_REGISTRY_ID = keccak256(
+    abi.encodePacked("FeeCurrencyWhitelist")
+  );
+  bytes32 constant FREEZER_REGISTRY_ID = keccak256(abi.encodePacked("Freezer"));
+  bytes32 constant GOLD_TOKEN_REGISTRY_ID = keccak256(abi.encodePacked("GoldToken"));
+  bytes32 constant GOVERNANCE_REGISTRY_ID = keccak256(abi.encodePacked("Governance"));
+  bytes32 constant GOVERNANCE_SLASHER_REGISTRY_ID = keccak256(
+    abi.encodePacked("GovernanceSlasher")
+  );
+  bytes32 constant LOCKED_GOLD_REGISTRY_ID = keccak256(abi.encodePacked("LockedGold"));
+  bytes32 constant RESERVE_REGISTRY_ID = keccak256(abi.encodePacked("Reserve"));
+  bytes32 constant RANDOM_REGISTRY_ID = keccak256(abi.encodePacked("Random"));
+  bytes32 constant SORTED_ORACLES_REGISTRY_ID = keccak256(abi.encodePacked("SortedOracles"));
+  bytes32 constant STABLE_TOKEN_REGISTRY_ID = keccak256(abi.encodePacked("StableToken"));
+  bytes32 constant VALIDATORS_REGISTRY_ID = keccak256(abi.encodePacked("Validators"));
+  // solhint-enable state-visibility
+
+  IRegistry public registry;
+
+  modifier onlyRegisteredContract(bytes32 identifierHash) {
+    require(registry.getAddressForOrDie(identifierHash) == msg.sender, "only registered contract");
+    _;
+  }
+
+  modifier onlyRegisteredContracts(bytes32[] memory identifierHashes) {
+    require(registry.isOneOf(identifierHashes, msg.sender), "only registered contracts");
+    _;
+  }
+
+  /**
+   * @notice Updates the address pointing to a Registry contract.
+   * @param registryAddress The address of a registry contract for routing to other contracts.
+   */
+  function setRegistry(address registryAddress) public onlyOwner {
+    require(registryAddress != address(0), "Cannot register the null address");
+    registry = IRegistry(registryAddress);
+    emit RegistrySet(registryAddress);
+  }
+
+  function getAccounts() internal view returns (IAccounts) {
+    return IAccounts(registry.getAddressForOrDie(ACCOUNTS_REGISTRY_ID));
+  }
+
+  function getAttestations() internal view returns (IAttestations) {
+    return IAttestations(registry.getAddressForOrDie(ATTESTATIONS_REGISTRY_ID));
+  }
+
+  function getElection() internal view returns (IElection) {
+    return IElection(registry.getAddressForOrDie(ELECTION_REGISTRY_ID));
+  }
+
+  function getExchange() internal view returns (IExchange) {
+    return IExchange(registry.getAddressForOrDie(EXCHANGE_REGISTRY_ID));
+  }
+
+  function getFeeCurrencyWhitelistRegistry() internal view returns (IFeeCurrencyWhitelist) {
+    return IFeeCurrencyWhitelist(registry.getAddressForOrDie(FEE_CURRENCY_WHITELIST_REGISTRY_ID));
+  }
+
+  function getFreezer() internal view returns (IFreezer) {
+    return IFreezer(registry.getAddressForOrDie(FREEZER_REGISTRY_ID));
+  }
+
+  function getGoldToken() internal view returns (IERC20) {
+    return IERC20(registry.getAddressForOrDie(GOLD_TOKEN_REGISTRY_ID));
+  }
+
+  function getGovernance() internal view returns (IGovernance) {
+    return IGovernance(registry.getAddressForOrDie(GOVERNANCE_REGISTRY_ID));
+  }
+
+  function getLockedGold() internal view returns (ILockedGold) {
+    return ILockedGold(registry.getAddressForOrDie(LOCKED_GOLD_REGISTRY_ID));
+  }
+
+  function getRandom() internal view returns (IRandom) {
+    return IRandom(registry.getAddressForOrDie(RANDOM_REGISTRY_ID));
+  }
+
+  function getReserve() internal view returns (IReserve) {
+    return IReserve(registry.getAddressForOrDie(RESERVE_REGISTRY_ID));
+  }
+
+  function getSortedOracles() internal view returns (ISortedOracles) {
+    return ISortedOracles(registry.getAddressForOrDie(SORTED_ORACLES_REGISTRY_ID));
+  }
+
+  function getStableToken() internal view returns (IStableToken) {
+    return IStableToken(registry.getAddressForOrDie(STABLE_TOKEN_REGISTRY_ID));
+  }
+
+  function getValidators() internal view returns (IValidators) {
+    return IValidators(registry.getAddressForOrDie(VALIDATORS_REGISTRY_ID));
+  }
+}
+
+contract CalledByVm {
+  modifier onlyVm() {
+    require(msg.sender == address(0), "Only VM can call");
+    _;
+  }
+}
+
+contract Initializable {
+  bool public initialized;
+
+  constructor(bool testingDeployment) public {
+    if (!testingDeployment) {
+      initialized = true;
+    }
+  }
+
+  modifier initializer() {
+    require(!initialized, "contract already initialized");
+    initialized = true;
+    _;
+  }
+}
+
+/**
+ * @title This interface describes the non- ERC20 shared interface for all Celo Tokens, and
+ * in the absence of interface inheritance is intended as a companion to IERC20.sol.
+ */
+interface ICeloToken {
+  function transferWithComment(address, uint256, string calldata) external returns (bool);
+  function name() external view returns (string memory);
+  function symbol() external view returns (string memory);
+  function decimals() external view returns (uint8);
+  function burn(uint256 value) external returns (bool);
+}
+
+interface ICeloVersionedContract {
+  /**
+   * @notice Returns the storage, major, minor, and patch version of the contract.
+    * @return Storage version of the contract.
+    * @return Major version of the contract.
+    * @return Minor version of the contract.
+    * @return Patch version of the contract.
+   */
+  function getVersionNumber() external pure returns (uint256, uint256, uint256, uint256);
+}
+
+contract GoldToken is
+  Initializable,
+  CalledByVm,
+  UsingRegistry,
+  IERC20,
+  ICeloToken,
+  ICeloVersionedContract
+{
+  using SafeMath for uint256;
+
+  // Address of the TRANSFER precompiled contract.
+  // solhint-disable state-visibility
+  address constant TRANSFER = address(0xff - 2);
+  string constant NAME = "Celo native asset";
+  string constant SYMBOL = "CELO";
+  uint8 constant DECIMALS = 18;
+  uint256 internal totalSupply_;
+  // solhint-enable state-visibility
+
+  mapping(address => mapping(address => uint256)) internal allowed;
+
+  // Burn address is 0xdEaD because truffle is having buggy behaviour with the zero address
+  address constant BURN_ADDRESS = address(0x000000000000000000000000000000000000dEaD);
+
+  event Transfer(address indexed from, address indexed to, uint256 value);
+
+  event TransferComment(string comment);
+
+  event Approval(address indexed owner, address indexed spender, uint256 value);
+
+  /**
+   * @notice Sets initialized == true on implementation contracts
+   * @param test Set to true to skip implementation initialization
+   */
+  constructor(bool test) public Initializable(test) {}
+
+  /**
+   * @notice Returns the storage, major, minor, and patch version of the contract.
+   * @return Storage version of the contract.
+   * @return Major version of the contract.
+   * @return Minor version of the contract.
+   * @return Patch version of the contract.
+   */
+  function getVersionNumber() external pure returns (uint256, uint256, uint256, uint256) {
+    return (1, 1, 2, 0);
+  }
+
+  /**
+   * @notice Used in place of the constructor to allow the contract to be upgradable via proxy.
+   * @param registryAddress Address of the Registry contract.
+   */
+  function initialize(address registryAddress) external initializer {
+    totalSupply_ = 0;
+    _transferOwnership(msg.sender);
+    setRegistry(registryAddress);
+  }
+
+  /**
+   * @notice Transfers CELO from one address to another.
+   * @param to The address to transfer CELO to.
+   * @param value The amount of CELO to transfer.
+   * @return True if the transaction succeeds.
+   */
+  // solhint-disable-next-line no-simple-event-func-name
+  function transfer(address to, uint256 value) external returns (bool) {
+    return _transferWithCheck(to, value);
+  }
+
+  /**
+   * @notice Transfers CELO from one address to another with a comment.
+   * @param to The address to transfer CELO to.
+   * @param value The amount of CELO to transfer.
+   * @param comment The transfer comment
+   * @return True if the transaction succeeds.
+   */
+  function transferWithComment(address to, uint256 value, string calldata comment)
+    external
+    returns (bool)
+  {
+    bool succeeded = _transferWithCheck(to, value);
+    emit TransferComment(comment);
+    return succeeded;
+  }
+
+  /**
+   * @notice This function allows a user to burn a specific amount of tokens.
+     Burning is implemented by sending tokens to the burn address.
+   * @param value: The amount of CELO to burn.
+   * @return True if burn was successful.
+   */
+  function burn(uint256 value) external returns (bool) {
+    // not using transferWithCheck as the burn address can potentially be the zero address
+    return _transfer(BURN_ADDRESS, value);
+  }
+
+  /**
+   * @notice Approve a user to transfer CELO on behalf of another user.
+   * @param spender The address which is being approved to spend CELO.
+   * @param value The amount of CELO approved to the spender.
+   * @return True if the transaction succeeds.
+   */
+  function approve(address spender, uint256 value) external returns (bool) {
+    require(spender != address(0), "cannot set allowance for 0");
+    allowed[msg.sender][spender] = value;
+    emit Approval(msg.sender, spender, value);
+    return true;
+  }
+
+  /**
+   * @notice Increases the allowance of another user.
+   * @param spender The address which is being approved to spend CELO.
+   * @param value The increment of the amount of CELO approved to the spender.
+   * @return True if the transaction succeeds.
+   */
+  function increaseAllowance(address spender, uint256 value) external returns (bool) {
+    require(spender != address(0), "cannot set allowance for 0");
+    uint256 oldValue = allowed[msg.sender][spender];
+    uint256 newValue = oldValue.add(value);
+    allowed[msg.sender][spender] = newValue;
+    emit Approval(msg.sender, spender, newValue);
+    return true;
+  }
+
+  /**
+   * @notice Decreases the allowance of another user.
+   * @param spender The address which is being approved to spend CELO.
+   * @param value The decrement of the amount of CELO approved to the spender.
+   * @return True if the transaction succeeds.
+   */
+  function decreaseAllowance(address spender, uint256 value) external returns (bool) {
+    uint256 oldValue = allowed[msg.sender][spender];
+    uint256 newValue = oldValue.sub(value);
+    allowed[msg.sender][spender] = newValue;
+    emit Approval(msg.sender, spender, newValue);
+    return true;
+  }
+
+  /**
+   * @notice Transfers CELO from one address to another on behalf of a user.
+   * @param from The address to transfer CELO from.
+   * @param to The address to transfer CELO to.
+   * @param value The amount of CELO to transfer.
+   * @return True if the transaction succeeds.
+   */
+  function transferFrom(address from, address to, uint256 value) external returns (bool) {
+    require(to != address(0), "transfer attempted to reserved address 0x0");
+    require(value <= balanceOf(from), "transfer value exceeded balance of sender");
+    require(
+      value <= allowed[from][msg.sender],
+      "transfer value exceeded sender's allowance for spender"
+    );
+
+    bool success;
+    (success, ) = TRANSFER.call.value(0).gas(gasleft())(abi.encode(from, to, value));
+    require(success, "CELO transfer failed");
+
+    allowed[from][msg.sender] = allowed[from][msg.sender].sub(value);
+    emit Transfer(from, to, value);
+    return true;
+  }
+
+  /**
+   * @notice Mints new CELO and gives it to 'to'.
+   * @param to The account for which to mint tokens.
+   * @param value The amount of CELO to mint.
+   */
+  function mint(address to, uint256 value) external onlyVm returns (bool) {
+    if (value == 0) {
+      return true;
+    }
+
+    require(to != address(0), "mint attempted to reserved address 0x0");
+    totalSupply_ = totalSupply_.add(value);
+
+    bool success;
+    (success, ) = TRANSFER.call.value(0).gas(gasleft())(abi.encode(address(0), to, value));
+    require(success, "CELO transfer failed");
+
+    emit Transfer(address(0), to, value);
+    return true;
+  }
+
+  /**
+   * @return The name of the CELO token.
+   */
+  function name() external view returns (string memory) {
+    return NAME;
+  }
+
+  /**
+   * @return The symbol of the CELO token.
+   */
+  function symbol() external view returns (string memory) {
+    return SYMBOL;
+  }
+
+  /**
+   * @return The number of decimal places to which CELO is divisible.
+   */
+  function decimals() external view returns (uint8) {
+    return DECIMALS;
+  }
+
+  /**
+   * @return The total amount of CELO in existence, including what the burn address holds.
+   */
+  function totalSupply() external view returns (uint256) {
+    return totalSupply_;
+  }
+
+  /**
+   * @return The total amount of CELO in existence, not including what the burn address holds.
+   */
+  function circulatingSupply() external view returns (uint256) {
+    return totalSupply_.sub(getBurnedAmount()).sub(balanceOf(address(0)));
+  }
+
+  /**
+   * @notice Gets the amount of owner's CELO allowed to be spent by spender.
+   * @param owner The owner of the CELO.
+   * @param spender The spender of the CELO.
+   * @return The amount of CELO owner is allowing spender to spend.
+   */
+  function allowance(address owner, address spender) external view returns (uint256) {
+    return allowed[owner][spender];
+  }
+
+  /**
+   * @notice Increases the variable for total amount of CELO in existence.
+   * @param amount The amount to increase counter by
+   */
+  function increaseSupply(uint256 amount) external onlyVm {
+    totalSupply_ = totalSupply_.add(amount);
+  }
+
+  /**
+   * @notice Gets the amount of CELO that has been burned.
+   * @return The total amount of Celo that has been sent to the burn address.
+   */
+  function getBurnedAmount() public view returns (uint256) {
+    return balanceOf(BURN_ADDRESS);
+  }
+
+  /**
+   * @notice Gets the balance of the specified address.
+   * @param owner The address to query the balance of.
+   * @return The balance of the specified address.
+   */
+  function balanceOf(address owner) public view returns (uint256) {
+    return owner.balance;
+  }
+
+  /**
+   * @notice internal CELO transfer from one address to another.
+   * @param to The address to transfer CELO to.
+   * @param value The amount of CELO to transfer.
+   * @return True if the transaction succeeds.
+   */
+  function _transfer(address to, uint256 value) internal returns (bool) {
+    require(value <= balanceOf(msg.sender), "transfer value exceeded balance of sender");
+
+    bool success;
+    (success, ) = TRANSFER.call.value(0).gas(gasleft())(abi.encode(msg.sender, to, value));
+    require(success, "CELO transfer failed");
+    emit Transfer(msg.sender, to, value);
+    return true;
+  }
+
+  /**
+   * @notice Internal CELO transfer from one address to another.
+   * @param to The address to transfer CELO to. Zero address will revert.
+   * @param value The amount of CELO to transfer.
+   * @return True if the transaction succeeds.
+   */
+  function _transferWithCheck(address to, uint256 value) internal returns (bool) {
+    require(to != address(0), "transfer attempted to reserved address 0x0");
+    return _transfer(to, value);
+  }
+}
+
diff --git a/e2e_test/foundry.toml b/e2e_test/foundry.toml
new file mode 100644
index 0000000000..0260703500
--- /dev/null
+++ b/e2e_test/foundry.toml
@@ -0,0 +1,6 @@
+[profile.default]
+src = "contracts"
+out = "out"
+libs = ["lib"]
+
+# See more config options https://github.com/foundry-rs/foundry/tree/master/config
diff --git a/e2e_test/test_token_duality.sh b/e2e_test/test_token_duality.sh
new file mode 100755
index 0000000000..17a47834a1
--- /dev/null
+++ b/e2e_test/test_token_duality.sh
@@ -0,0 +1,21 @@
+#/bin/bash
+set -eo pipefail
+
+# Before execution this script, run geth with a command like
+# make geth && build/bin/geth --dev --http --http.api eth,web3,net console --exec "eth.sendTransaction({from: eth.coinbase, to: '0x42cf1bbc38BaAA3c4898ce8790e21eD2738c6A4a', value: web3.toWei(50, 'ether')}); admin.sleep(20)"
+
+export ETH_RPC_URL=http://127.0.0.1:8545
+ACC_ADDR=0x42cf1bbc38BaAA3c4898ce8790e21eD2738c6A4a
+ACC_PRIVKEY=0x2771aff413cac48d9f8c114fabddd9195a2129f3c2c436caa07e27bb7f58ead5
+
+REGISTRY_ADDR=0x000000000000000000000000000000000000ce10
+
+# Deploy and register token
+TOKEN_ADDR=$(forge create --private-key $ACC_PRIVKEY contracts/GoldToken.sol:GoldToken --constructor-args false | awk '/Deployed to/ {print $3}')
+cast send --private-key $ACC_PRIVKEY $REGISTRY_ADDR 'function setAddressFor(string calldata identifier, address addr) external' GoldToken $TOKEN_ADDR
+echo Account address: $ACC_ADDR, token address: $TOKEN_ADDR
+
+# Send token and check balance
+cast balance 0x000000000000000000000000000000000000dEaD
+cast send --private-key $ACC_PRIVKEY $TOKEN_ADDR 'function transfer(address to, uint256 value) external returns (bool)' 0x000000000000000000000000000000000000dEaD 100
+cast balance 0x000000000000000000000000000000000000dEaD