Demonstrates 3 issues with enums / token burns

contracts/mocks/ERC3525_Testing.sol

@@ -53,6 +53,14 @@ contract ERC3525_Testing is ERC3525SlotEnumerableUpgradeable {
         return _isApprovedOrOwner(operator_, tokenId_);
     }
 
+    function splitValue(uint256 fromToken_, uint256 value_) public virtual returns (uint256 tokenId) {
+        return _splitValue(fromToken_, value_);
+    }
+
+    function mergeValue(uint256 fromToken_, uint256 toToken_) public virtual returns (uint256 tokenId) {
+        return _mergeValue(fromToken_, toToken_);
+    }
+
     function slotURI(
         uint256 /*slot_*/
     ) public pure override returns (string memory) {

test/erc3525/ERC3525.burn.ts

@@ -25,5 +25,18 @@ export function shouldBehaveLikeSemiFungibleTokenBurn(): void {
 
       await expect(user.sft.burn(2)).to.be.revertedWith("NotApprovedOrOwner");
     });
+
+    it("doesnt reallocate value after a token is burnt", async function () {
+      const { sft, user, anon } = await setupTestERC3525();
+      await sft.mintValue(user.address, 1, 10);
+
+      expect(await sft.ownerOf(1)).to.equal(user.address);
+      await user.sft["transferFrom(uint256,address,uint256)"](1, anon.address, 5);
+      expect(await sft.ownerOf(2)).to.equal(anon.address);
+
+      await anon.sft.burn(2);
+      expect((await sft["balanceOf(address)"](anon.address)).isZero()).to.be.true;
+      expect((await sft["balanceOf(uint256)"](1)).toNumber()).to.equal(5);
+    });
   });
 }

test/erc3525/ERC3525.mint.ts

@@ -44,5 +44,19 @@ export function shouldBehaveLikeSemiFungibleTokenMint(): void {
       expect(await sft["balanceOf(uint256)"](1)).to.be.eq("1000000");
       expect(await sft["balanceOf(uint256)"](2)).to.be.eq("2000000");
     });
+
+    it("enumerates slots correctly", async function () {
+      const { sft, user, anon } = await setupTestERC3525();
+      await sft.mintValue(user.address, 1, 10);
+      await user.sft["transferFrom(uint256,address,uint256)"](1, anon.address, 5);
+      expect(await sft.ownerOf(1)).to.be.eq(user.address);
+      expect(await sft.ownerOf(2)).to.be.eq(anon.address);
+      expect(await sft["tokenInSlotByIndex"](1, 0)).to.be.eq("1");
+      expect(await sft.totalSupply()).to.be.eq(2);
+
+      //these fail:
+      //expect(await sft["tokenInSlotByIndex"](1, 1)).to.be.eq("2"); //reverts
+      expect(await sft.tokenSupplyInSlot(1)).to.be.eq(2); //returns 1
+    });
   });
 }

test/erc3525/ERC3525.transfer.ts

@@ -66,5 +66,18 @@ export function shouldBehaveLikeSemiFungibleTokenTransfer(): void {
       expect(await sft["balanceOf(uint256)"](1)).to.be.eq("500000");
       expect(await sft["balanceOf(uint256)"](2)).to.be.eq("500000");
     });
+
+    it("doesnt decrease total supply after nfts have been merged", async function () {
+      const { sft, user } = await setupTestERC3525();
+      await sft.mintValue(user.address, 1, 10);
+      await user.sft.splitValue(1, 5);
+      expect(await sft["balanceOf(address)"](user.address)).to.be.equal(2);
+      await user.sft.mergeValue(2, 1);
+      await user.sft.burn(2);
+      expect(await sft["balanceOf(address)"](user.address)).to.be.equal(1);
+
+      //fails: totalSupply is still 2
+      expect(await sft.totalSupply()).to.be.equal(1);
+    });
   });
 }

test/hypercert_minter/HyperCertMinter.split.merge.ts

@@ -73,4 +73,25 @@ export function shouldBehaveLikeHypercertMinterSplitAndMerge(): void {
     expect(await minter["balanceOf(uint256)"](3)).to.be.eq("50");
     expect(await minter.tokenSupplyInSlot(slot)).to.be.eq(2);
   });
+
+  it("doesnt decrease total supply after nfts have been merged", async function () {
+    const { user, minter, anon } = await setupTest();
+    const claim = await newClaim({ fractions: [10] });
+    const data = encodeClaim(claim);
+
+    await minter.mint(user.address, data);
+    await user.minter["transferFrom(uint256,address,uint256)"](1, anon.address, 5);
+    expect(await minter["balanceOf(address)"](user.address)).to.be.equal(1);
+    expect(await minter["balanceOf(address)"](anon.address)).to.be.equal(1);
+    expect(await minter.totalSupply()).to.be.equal(2);
+
+    await anon.minter["safeTransferFrom(address,address,uint256)"](anon.address, user.address, 2);
+    await user.minter.merge([2, 1]);
+    expect(await minter["balanceOf(address)"](user.address)).to.be.equal(1);
+    expect(await minter["balanceOf(address)"](anon.address)).to.be.equal(0);
+    expect(await minter["balanceOf(uint256)"](1)).to.be.equal(10);
+
+    //fails: totalSupply is still 2
+    expect(await minter.totalSupply()).to.be.equal(1);
+  });
 }