vault: burning funds

contracts/Vault.sol

@@ -41,4 +41,11 @@ contract Vault {
     delete _available[controller][context][recipient];
     _token.safeTransfer(Recipient.unwrap(recipient), amount);
   }
+
+  function burn(Context context, Recipient recipient) public {
+    Controller controller = Controller.wrap(msg.sender);
+    uint256 amount = _available[controller][context][recipient];
+    delete _available[controller][context][recipient];
+    _token.safeTransfer(address(0xdead), amount);
+  }
 }

test/Vault.tests.js

@@ -96,4 +96,35 @@ describe("Vault", function () {
       expect(after).to.equal(before)
     })
   })
+
+  describe("burning", function () {
+    const context = randomBytes(32)
+    const amount = 42
+
+    beforeEach(async function () {
+      await token.connect(account).approve(vault.address, amount)
+      await vault.deposit(context, account.address, amount)
+    })
+
+    it("can burn a deposit", async function () {
+      await vault.burn(context, account.address)
+      expect(await vault.balance(context, account.address)).to.equal(0)
+    })
+
+    it("no longer allows withdrawal", async function () {
+      await vault.burn(context, account.address)
+      const before = await token.balanceOf(account.address)
+      await vault.withdraw(context, account.address)
+      const after = await token.balanceOf(account.address)
+      expect(after).to.equal(before)
+    })
+
+    it("moves the tokens to address 0xdead", async function () {
+      const dead = "0x000000000000000000000000000000000000dead"
+      const before = await token.balanceOf(dead)
+      await vault.burn(context, account.address)
+      const after = await token.balanceOf(dead)
+      expect(after - before).to.equal(amount)
+    })
+  })
 })