diff --git a/test/DCO2s.t.sol b/test/DCO2s.t.sol
index cc2076b..9bc5638 100644
--- a/test/DCO2s.t.sol
+++ b/test/DCO2s.t.sol
@@ -6,9 +6,11 @@ import {DCO2s} from "../src/DCO2s.sol";
 
 contract DCO2sTest is Test {
     DCO2s public dco2sc;
+    string public baseURL;
 
     function setUp() public {
         dco2sc = new DCO2s(address(this), address(this), "DCO2s", "DCO2");
+        baseURL = "https://gateway.decentralizedscience.org/ipfs/";
     }
 
     // @notice this code safe mints an NFT to address 0x1
@@ -18,14 +20,29 @@ contract DCO2sTest is Test {
         assertEq(dco2sc.ownerOf(0), to, "Token should be minted to specified address.");
     }
 
+    function testMintFromEnv() public {
+        address to = address(0x1);
+        string memory nft68 = vm.envString("NFT68");
+        dco2sc.safeMint(to,nft68);
+        assertEq(dco2sc.ownerOf(0), to, "Token should be minted to specified address.");
+    }
+
+    // @notice: here we test getting the Base and full URIS
+    function testGetURI68() public {
+        string memory URI = vm.envString("NFT68");
+        dco2sc.safeMint(address(1), URI);
+        string memory tokenURI = dco2sc.tokenURI(0);
+        console.log(tokenURI);
+        assertEq(tokenURI, string.concat(baseURL, URI));
+    }
+
     // @notice: here we test getting the Base and full URIS
     function testGetURI() public {
-        string memory _baseURL = "https://gateway.decentralizedscience.org/ipfs/";
         string memory URI = "bafkreibc6p3y36yjmeqqnttqfrpb2yttxa6aonoywxwdxl7nqym4jj3jwa";
         dco2sc.safeMint(address(1), URI);
         string memory tokenURI = dco2sc.tokenURI(0);
         console.log(tokenURI);
-        assertEq(tokenURI, string.concat(_baseURL,URI));
+        assertEq(tokenURI, string.concat(baseURL,URI));
 
     }
 
@@ -41,6 +58,33 @@ contract DCO2sTest is Test {
 
     // @notice use the basic Enumerable properties
     // function testEnumerable() public {}
+    function testEnumerableTokenByIndex() public {
+        string[5] memory nfts = [
+            "bafkreibc6p3y36yjmeqqnttqfrpb2yttxa6aonoywxwdxl7nqym4jj3jwa",
+            "bafkreifqztiwfutjik4wfs3gyfdyrff7cugi4mcctluunrrbp5cgareisq",
+            "bafkreibffiehtv4ntajq5vjwpl7q44i6cjbg54lm5hkoa665ue2taspiyu",
+            "bafkreidcf5baqb5wevs6vyd7dtd3j7rzrq65uyqasj4dbkcy6na4ig3ay",
+            "bafkreiglyvpxwrxdvruit3oiw2lvkxqqxn7ojquw4gl7ck6szewz6t6cam"];
+
+        for(uint i; i < nfts.length; i++){
+            dco2sc.safeMint(address(1), nfts[i]);
+        }
+
+        assertEq(nfts.length, dco2sc.totalSupply());
+
+        // Test for token By Index 4
+        uint tokenID = dco2sc.tokenByIndex(4);
+        assertEq(nfts[4], nfts[tokenID]);
+
+        // Test for token By Index 3
+        tokenID = dco2sc.tokenByIndex(3);
+        assertEq(nfts[3], nfts[tokenID]);
+
+        // Test tokenURI from by ID3
+        string memory tokenURI = dco2sc.tokenURI(tokenID);
+        console.log(tokenURI);
+        assertEq(tokenURI, string.concat(baseURL,nfts[3]));
+    }
 
     // @notice: testFailMintToZeroAddress test that cannot safe mint to address 0
     function testFailMintToZeroAddress() public {