Add test to improve test coverage

contracts/TransmuteDPOS.sol

@@ -84,8 +84,8 @@ contract TransmuteDPOS is TransmuteToken, RoundManager, ProviderPool {
     require(_feeShare <= 100);
     Provider storage p = providers[msg.sender];
     Delegator storage d = delegators[msg.sender];
+    // Provider has to be a Delegator to himself
     require(d.delegateAddress == msg.sender);
-    require(d.amountBonded > 0);
     if (p.status == ProviderStatus.Unregistered) {
       numberOfProviders = numberOfProviders.add(1);
       addProvider(msg.sender, p.totalAmountBonded);
@@ -108,6 +108,7 @@ contract TransmuteDPOS is TransmuteToken, RoundManager, ProviderPool {
   }
 
   function bond(address _provider, uint _amount) external {
+    require(_amount > 0);
     Provider storage p = providers[_provider];
     // A delegator is only allowed to bond to an Unregistered provider if the provider is himself
     // otherwise _provider has to be associated with a Registered provider

test/TestTransmuteDPOS.spec.js

@@ -231,8 +231,12 @@ contract('TransmuteDPOS', accounts => {
       assert.equal(10, firstDelegator[1]); // [1] is amountBonded
     });
 
-    it('should increase the totalAmountBonded of the Provider', async () => {
+    it('should fail if amount is zero', async () => {
       await tdpos.approve(contractAddress, 20, {from: accounts[6]});
+      await assertFail( tdpos.bond(accounts[0], 0, {from: accounts[6]}) );
+    });
+
+    it('should increase the totalAmountBonded of the Provider', async () => {
       await tdpos.bond(accounts[0], 20, {from: accounts[6]});
       const provider = await tdpos.providers.call(accounts[0]);
       assert.equal(31, provider[5].toNumber()); // [5] is totalAmountBonded