test: size limits of a single contract

WIP:
- [x] (more or less done) map size limits
- [ ] max number of cells — there's an issue with Fift decompiler,
blocking progress. Besides, the total limit from TON side is known:
$2^{16}$ cells per account state, according to [config param
43](https://docs.ton.org/develop/howto/blockchain-configs#param-43)
- [ ] max number of struct fields

Author: novusnota

src/test/size-limits/cells.spec.ts

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+import { toNano } from "@ton/core";
+import { Blockchain, SandboxContract, TreasuryContract } from "@ton/sandbox";
+import { MaxCellNumberTester as TestContract } from "./contracts/output/cell-number-limits_MaxCellNumberTester";
+import "@ton/test-utils";
+
+// According to config param 43, the absolute max is 2^16 cells by default
+// The test below is used to know what's the max for Tact contracts
+describe("cell number limits", () => {
+    let blockchain: Blockchain;
+    let treasure: SandboxContract<TreasuryContract>;
+    let contract: SandboxContract<TestContract>;
+
+    beforeEach(async () => {
+        blockchain = await Blockchain.create();
+        blockchain.verbosity.print = false;
+        treasure = await blockchain.treasury("treasure", {
+            balance: 1_000_000_000n,
+            resetBalanceIfZero: true,
+        });
+        contract = blockchain.openContract(await TestContract.fromInit());
+
+        const deployResult = await contract.send(
+            treasure.getSender(),
+            { value: toNano("100000") },
+            null,
+        );
+        expect(deployResult.transactions).toHaveTransaction({
+            from: treasure.address,
+            to: contract.address,
+            success: true,
+            deploy: true,
+        });
+    });
+
+    it("should test cell number limits", async () => {
+        // TODO: a test, that adds more cells to the mix.
+        const sendResult = await contract.send(
+            treasure.getSender(),
+            { value: toNano("1") },
+            null, // FIXME: ← placeholder, until issues with Fift decompiler of the contract are resolved
+            // {
+            //     $$type: "AddCells",
+            //     number: BigInt(16), // NOTE: adjust
+            // },
+        );
+        expect(sendResult.transactions).toHaveTransaction({
+            from: treasure.address,
+            to: contract.address,
+            success: false,
+            actionResultCode: 50,
+        });
+    });
+});

src/test/size-limits/contracts/cell-number-limits.tact

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+// giantNestedCell
+import "./giant-nested-cell.tact";
+
+message AddCells { number: Int as uint8 }
+
+contract MaxCellNumberTester {
+    c1: Cell; c2: Cell; c3: Cell; c4: Cell;
+    c5: Cell; c6: Cell; c7: Cell; c8: Cell;
+    c9: Cell; c10: Cell; c11: Cell; c12: Cell;
+    c13: Cell; c14: Cell; c15: Cell; c16: Cell;
+    cExtra: Cell;
+
+    // NOTE: for some reason, Fift's BoC cannot handle neither 2^13 nor 2^12 cells.
+    // It just breaks 1k cells short of deserializing each. May be an issue of this wasm fift version (we may need to upgrade it to recently released 2024.09 version)
+
+    /// Setup
+    init() {
+        self.c1 = giantNestedCell;  // 2^{12} - 2 empty cells
+        self.c2 = giantNestedCell;  // 2^{12} - 2 empty cells
+        self.c3 = giantNestedCell;  // 2^{12} - 2 empty cells
+        self.c4 = giantNestedCell;  // 2^{12} - 2 empty cells
+        self.c5 = giantNestedCell;  // 2^{12} - 2 empty cells
+        self.c6 = giantNestedCell;  // 2^{12} - 2 empty cells
+        self.c7 = giantNestedCell;  // 2^{12} - 2 empty cells
+        self.c8 = giantNestedCell;  // 2^{12} - 2 empty cells
+        self.c9 = giantNestedCell;  // 2^{12} - 2 empty cells
+        self.c10 = giantNestedCell; // 2^{12} - 2 empty cells
+        self.c11 = giantNestedCell; // 2^{12} - 2 empty cells
+        self.c12 = giantNestedCell; // 2^{12} - 2 empty cells
+        self.c13 = giantNestedCell; // 2^{12} - 2 empty cells
+        self.c14 = giantNestedCell; // 2^{12} - 2 empty cells
+        self.c15 = giantNestedCell; // 2^{12} - 2 empty cells
+        self.c16 = giantNestedCell; // 2^{12} - 2 empty cells
+        self.cExtra = emptyCell();  // 1 empty cell
+        // Overall: 2^{16} - 2^{4} + 1 = 65520 cells
+    }
+
+    /// To handle deployment
+    receive() {}
+
+    /// To add X cells
+    receive(msg: AddCells) {
+        let b = beginCell().storeRef(emptyCell());
+
+        // 2 in b, 1 in cExtra already, and X in msg.number, therefore: X - (2 - 1)
+        repeat (msg.number - 1) {
+            b = beginCell().storeRef(b.endCell());
+        }
+
+        self.cExtra = b.endCell();
+    }
+}

src/test/size-limits/contracts/giant-nested-cell.tact

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+//
+// map<Int, Int>
+//
+
+message AddIntInt {
+    batchSize: Int as uint8;
+    startingValue: Int as uint16;
+}
+
+contract MapIntInt {
+    /// Target map
+    m: map<Int as uint16, Int as uint16>;
+
+    /// To handle deployment
+    receive() {}
+
+    /// To add an item
+    receive(msg: AddIntInt) {
+        let curVal = msg.startingValue;
+        repeat (msg.batchSize) {
+            self.m.set(curVal, curVal);
+            curVal += 1;
+        }
+    }
+}
+
+//
+// map<Int, Bool>
+//
+
+message AddIntBool {
+    batchSize: Int as uint8;
+    startingKey: Int;
+}
+
+contract MapIntBool {
+    /// Target map
+    m: map<Int, Bool>;
+
+    /// To handle deployment
+    receive() {}
+
+    /// To add an item
+    receive(msg: AddIntBool) {
+        let curVal = msg.startingKey;
+        repeat (msg.batchSize) {
+            self.m.set(curVal, false);
+            curVal += 1;
+        }
+    }
+}
+
+//
+// map<Int, Cell>
+//
+
+message AddIntCell {
+    batchSize: Int as uint8;
+    startingKey: Int;
+}
+
+contract MapIntCell {
+    /// Target map
+    m: map<Int, Cell>;
+
+    /// To handle deployment
+    receive() {}
+
+    /// To add an item
+    receive(msg: AddIntCell) {
+        let curVal = msg.startingKey;
+        repeat (msg.batchSize) {
+            self.m.set(curVal, emptyCell());
+            curVal += 1;
+        }
+    }
+}
+
+//
+// map<Int, Address>
+//
+
+message AddIntAddress {
+    batchSize: Int as uint8;
+    startingKey: Int;
+}
+
+contract MapIntAddress {
+    /// Target map
+    m: map<Int, Address>;
+
+    /// To handle deployment
+    receive() {}
+
+    /// To add an item
+    receive(msg: AddIntAddress) {
+        let curVal = msg.startingKey;
+        let myAddr = myAddress(); // TODO: different addresses
+        repeat (msg.batchSize) {
+            self.m.set(curVal, myAddr);
+            curVal += 1;
+        }
+    }
+}
+
+//
+// map<Int, Struct>
+//
+
+message AddIntStruct {
+    batchSize: Int as uint8;
+    startingKey: Int;
+}
+
+struct BoolBool { yes: Bool }
+
+contract MapIntStruct {
+    /// Target map
+    m: map<Int, BoolBool>;
+
+    /// To handle deployment
+    receive() {}
+
+    /// To add an item
+    receive(msg: AddIntStruct) {
+        let curVal = msg.startingKey;
+        let stBool = BoolBool{ yes: true };
+        repeat (msg.batchSize) {
+            self.m.set(curVal, stBool);
+            curVal += 1;
+        }
+    }
+}
+
+//
+// map<Int, Message>
+//
+
+message AddIntMessage {
+    batchSize: Int as uint8;
+    startingKey: Int;
+}
+
+message(0x2A) TheAnswer {}
+
+contract MapIntMessage {
+    /// Target map
+    m: map<Int, TheAnswer>;
+
+    /// To handle deployment
+    receive() {}
+
+    /// To add an item
+    receive(msg: AddIntMessage) {
+        let curVal = msg.startingKey;
+        let msgEmpty = TheAnswer{};
+        repeat (msg.batchSize) {
+            self.m.set(curVal, msgEmpty);
+            curVal += 1;
+        }
+    }
+}
+
+// TODO: all the same, but with Addresses as keys.
+// NOTE: contractAddress(StateInit{code: emptyCell(), data: beginCell().storeUint(curVal, 16).endCell()})