Expose calculateTimelockDuration externally

contracts/prize-pool/PrizePool.sol

@@ -643,6 +643,22 @@ abstract contract PrizePool is OwnableUpgradeSafe, RelayRecipient, ReentrancyGua
   /// @param amount The amount the user is withdrawing
   /// @param controlledToken The type of collateral the user is withdrawing (i.e. ticket or sponsorship)
   /// @return durationSeconds The duration of the timelock in seconds
+  function calculateTimelockDuration(
+    address from,
+    address controlledToken,
+    uint256 amount
+  )
+    external
+    returns (uint256)
+  {
+    return _calculateTimelockDuration(from, controlledToken, amount);
+  }
+
+  /// @dev Calculates a timelocked withdrawal duration and credit consumption.
+  /// @param from The user who is withdrawing
+  /// @param amount The amount the user is withdrawing
+  /// @param controlledToken The type of collateral the user is withdrawing (i.e. ticket or sponsorship)
+  /// @return durationSeconds The duration of the timelock in seconds
   function _calculateTimelockDuration(
     address from,
     address controlledToken,

test/CompoundPrizePool.test.js

@@ -581,6 +581,20 @@ describe('CompoundPrizePool', function() {
       })
     })
 
+    describe('calculateTimelockDuration()', () => {
+      it('should return the timelock duration', async () => {
+        let amount = toWei('10')
+
+        await cToken.mock.balanceOfUnderlying.returns('0')
+        await ticket.mock.totalSupply.returns(amount)
+        await ticket.mock.balanceOf.withArgs(wallet._address).returns(amount)
+
+        // force current time and check
+        await prizePool.setCurrentTime('1')
+        expect(await call(prizePool, 'calculateTimelockDuration', wallet._address, ticket.address, amount)).to.equal(10)
+      })
+    })
+
     describe('estimateAccruedInterestOverBlocks()', () => {
       it('should get the supply rate from the yield service to estimate interest per block', async function () {
         const deposit = toWei('100')