evm: add fuzz tests (#239)

* rate_limit: add fuzz test for outbound transfers

* trimmed_amounts: add fuzz tests for left inverse and saturating add

* trimmed_amount: add more fuzz tests

* ntt_manager: add fuzz test for countSetBits

* rate_limit: add fuzz test for inbound rate limiting

* rate_limit: add fuzz test for backflow

* fix: use bound instead of assume for uints

* evm: remove unnecessary bounds in fuzz test for saturatingAdd

* evm: change the inputs to the circular backflow tests to uint256

* evm: modify trimming is left inverse to support more decimals

* evm: rebasing changes

* evm: use bound in place of vm.assume

* evm: test against inputs greater than u64MAX

* evm: use explicit error selectors in reverts

* evm: rename inputs for more clarity

* evm: simplify trimming is left inverse test

* evm: test additional invariants

* evm: use bound instead of assume

---------

Co-authored-by: Rahul Maganti <rahulmaganti@rahuls-mbp.mynetworksettings.com>

Author: RahulMaganti47

evm/test/NttManager.t.sol

@@ -72,12 +72,20 @@ contract TestNttManager is Test, IRateLimiterEvents {
 
     // === pure unit tests
 
-    function test_countSetBits() public {
-        assertEq(countSetBits(5), 2);
-        assertEq(countSetBits(0), 0);
-        assertEq(countSetBits(15), 4);
-        assertEq(countSetBits(16), 1);
-        assertEq(countSetBits(65535), 16);
+    // naive implementation of countSetBits to test against
+    function simpleCount(uint64 n) public pure returns (uint8) {
+        uint8 count;
+
+        while (n > 0) {
+            count += uint8(n & 1);
+            n >>= 1;
+        }
+
+        return count;
+    }
+
+    function testFuzz_countSetBits(uint64 n) public {
+        assertEq(simpleCount(n), countSetBits(n));
     }
 
     // === Deployments with rate limiter disabled