feat: require minimum stake to allocate zero tokens

Author: abarmat

contracts/staking/Staking.sol

@@ -1120,9 +1120,11 @@ contract Staking is StakingV2Storage, GraphUpgradeable, IStaking, Multicall {
             // Needs to have free capacity not used for other purposes to allocate
             require(getIndexerCapacity(_indexer) >= _tokens, "!capacity");
         } else {
-            // Allocating zero-tokens still needs to have stake
-            // Minimum indexer stake is managed by stake/unstake
-            require(stakes[_indexer].tokensSecureStake() > 0, "!stake");
+            // Allocating zero-tokens still needs to comply with stake requirements
+            require(
+                stakes[_indexer].tokensSecureStake() >= minimumIndexerStake,
+                "!minimumIndexerStake"
+            );
         }
 
         // Creates an allocation

test/staking/allocation.test.ts

@@ -357,9 +357,9 @@ describe('Staking:Allocation', () => {
       await expect(tx).revertedWith('!capacity')
     })
 
-    it('reject allocate zero tokens if no tokens staked', async function () {
+    it('reject allocate zero tokens if no minimum stake', async function () {
       const tx = allocate(toBN('0'))
-      await expect(tx).revertedWith('!stake')
+      await expect(tx).revertedWith('!minimumIndexerStake')
     })
 
     context('> when staked', function () {