feat(reward-contracts): S curve

- S curve + tests added
- some existing tests reworked/fixed
- testing on concrete error messages added
- eternal storage/proxy removed

.solcover.js

@@ -1,3 +1,5 @@
 module.exports = {
-  skipFiles: ['interfaces','libs']
+    skipFiles: ['interfaces','libs', 'misc/Ownable.sol'],
+    compileCommand: 'npx truffle compile',
+    testCommand: 'npx truffle test --network coverage'
 }

contracts/reward/BlockReward.sol

@@ -90,16 +90,24 @@ contract BlockReward is SCurveProvider, IBlockReward {
         delete payoutAddresses[msg.sender];
     }
 
+    /// @notice The function that is called by the client to issue rewards at a new block. The rewards are
+    /// minted: the balances of the corresponing addresses are simply increased with the amount
+    /// @dev It is a service transaction invoked by system, which doesn't cost anyhting but still can
+    /// modify state. Cannot emit events.
+    /// @param benefactors List of addresses that can be rewarded
+    /// @param kind List of type codes belonging to the benefactors. They determine the category
+    /// an address belongs to. 0 is for block authors which we are only interested in
+    /// @return List of addreses to be rewarded, and list of corresponding reward amounts in wei
     function reward(address[] calldata benefactors, uint16[] calldata kind)
         external
         onlySystem
         returns (address[] memory, uint256[] memory)
     {
-        require(benefactors.length == kind.length, "Benefactors/types length differs");
-        require(benefactors.length == 1, "Benefactors length is not 1");
-        require(kind[0] == 0, "Benefactor is not the block author.");
+        require(benefactors.length == kind.length, "Benefactors/types list length differs");
+        require(benefactors.length == 1, "Benefactors list length is not 1");
+        require(kind[0] == 0, "Benefactor is not the block author");
 
-        if (benefactors[0] == address(0)) {
+        if (benefactors[0] == address(0) || _checkRewardPeriodEnded(block.number)) {
             return (new address[](0), new uint256[](0));
         }
 

contracts/reward/SCurveProvider.sol

@@ -1,13 +1,193 @@
 pragma solidity ^0.5.4;
 
 
+/// @title S Curve Reward provider
+/// @notice Provides the appropriate block author rewards
+/// based on points of a discrete, inverse S curve
 contract SCurveProvider {
 
+    /// Discrete points of the curve
+    uint256[] public sCurve;
+    /// Discrete step size
+    uint256 public blockStepSize;
+    /// End of the reward period (both block- and community reward)
+    /// expressed in block number
+    uint256 public rewardPeriodEnd;
+
+    constructor()
+        public
+    {
+        _initCurve();
+    }
+
+    /// @notice Returns the block reward amount based on the block number
+    /// and points of the S curve
+    /// @param _currentBlock The block number to calculate the reward to
+    /// @return The block reward amount in wei
     function getBlockReward(uint256 _currentBlock)
         public
         view
         returns (uint256)
     {
-        return 5;
+        if (_checkRewardPeriodEnded(_currentBlock)) {
+            return 0;
+        }
+        return sCurve[_currentBlock / blockStepSize];
+    }
+
+    /// @notice Checks whether the reward period is over or not (block and community)
+    /// @return True if the reward period has ended, false otherwise
+    function checkRewardPeriodEnded()
+        public
+        view
+        returns (bool)
+    {
+        return _checkRewardPeriodEnded(block.number);
+    }
+
+    /// @notice Checks whether the block reward period is over or not
+    /// @param _currentBlock The block number to check on
+    /// @return True if the block reward period has ended, false otherwise
+    function _checkRewardPeriodEnded(uint256 _currentBlock)
+        internal
+        view
+        returns (bool)
+    {
+        return (_currentBlock >= rewardPeriodEnd);
+    }
+
+    // solhint-disable function-max-lines
+    /// @dev Inits the S curve. Values are hardcoded,
+    /// everyhting is calculated beforehand
+    function _initCurve()
+        private
+    {   
+        sCurve = [
+            uint256(304418979390926464),
+            304418979390926464,
+            304418979390926464,
+            304418979390926464,
+            304418979390926464,
+            304418979390926464,
+            304418979390926464,
+            304369560376526464,
+            304221303333326464,
+            303974208261326464,
+            303628275160526464,
+            303183504030926464,
+            302639894872526464,
+            301997447685326464,
+            301256162469326464,
+            300416039224526464,
+            299477077950926464,
+            298439278648526464,
+            297302641317326464,
+            296067165957326464,
+            294732852568526464,
+            293299701150926464,
+            291767711704526464,
+            290136884229326464,
+            288407218725326464,
+            286578715192526464,
+            284651373630926464,
+            282625194040526464,
+            280500176421326464,
+            278276320773326464,
+            275953627096526464,
+            273532095390926464,
+            271011725656526464,
+            268392517893326464,
+            265674472101326464,
+            262857588280526464,
+            259941866430926464,
+            256927306552526464,
+            253813908645326464,
+            250601672709326464,
+            247290598744526464,
+            243880686750926464,
+            240371936728526464,
+            236764348677326464,
+            233057922597326464,
+            229252658488526464,
+            225348556350926464,
+            221345616184526464,
+            217243837989326464,
+            213043221765326464,
+            208743767512526464,
+            204345475230926464,
+            199848344920526464,
+            195252376581326464,
+            190557570213326464,
+            185763925816526464,
+            180871443390926464,
+            175880122936526464,
+            170789964453326464,
+            165600967941326464,
+            160117606656000000,
+            154824830213760000,
+            149621007997440000,
+            144506140007040000,
+            139480226242560000,
+            134543266704000000,
+            129695261391360000,
+            124936210304640000,
+            120266113443840000,
+            115684970808960000,
+            111192782400000000,
+            106789548216960000,
+            102475268259840000,
+            98249942528640000,
+            94113571023360000,
+            90066153744000000,
+            86107690690560000,
+            82238181863040000,
+            78457627261440000,
+            74766026885760000,
+            71163380736000000,
+            67649688812160000,
+            64224951114240000,
+            60889167642240000,
+            57642338396160000,
+            54484463376000000,
+            51415542581760000,
+            48435576013440000,
+            45544563671040000,
+            42742505554560000,
+            40029401664000000,
+            37405251999360000,
+            34870056560640000,
+            32423815347840000,
+            30066528360960000,
+            27798195600000000,
+            25618817064960000,
+            23528392755840000,
+            21526922672640000,
+            19614406815360000,
+            17790845184000000,
+            16056237778560000,
+            14410584599040000,
+            12853885645440000,
+            11386140917760000,
+            10007350416000000,
+            8717514140160000,
+            7516632090240000,
+            6404704266240000,
+            5381730668160000,
+            4447711296000000,
+            3602646149760000,
+            2846535229440000,
+            2179378535040000,
+            1601176066560000,
+            1111927824000000,
+            711633807360000,
+            400294016640000,
+            177908451840000,
+            44477112960000
+        ];
+        // roughly 1 month with a 5 sec step size
+        blockStepSize = 525600;
+        //roughly 10 years with a 5 sec step size
+        rewardPeriodEnd = blockStepSize * sCurve.length;
     }
-}
+    // solhint-enable function-max-lines
+}