Implements comprehensive transaction validation for mock-chain package.

packages/mock-chain/src/index.ts

@@ -2,3 +2,4 @@ export * from "./execution";
 export * from "./mockChain";
 export * from "./party";
 export * from "./objectMocking";
+export * from "./transactionChecks";

packages/mock-chain/src/mockChain.spec.ts

@@ -554,3 +554,89 @@ describe("Contract execution and chain mocking", () => {
     expect(chain.timestamp - params.timestamp).to.be.equal(0);
   });
 });
+
+describe("Transaction validation checks", () => {
+  it("Should validate minimum nanoergs per box", () => {
+    const chain = new MockChain();
+    const alice = chain.newParty("Alice");
+    alice.addBalance({ nanoergs: 10000000n });
+
+    const unsignedTransaction = new TransactionBuilder(chain.height)
+      .from(alice.utxos)
+      .to(new OutputBuilder("100", alice.address)) // Too small value
+      .sendChangeTo(alice.address)
+      .build();
+
+    // Should fail with validation error
+    expect(() => chain.execute(unsignedTransaction, { signers: [alice] }))
+      .to.throw("Transaction validation failed");
+  });
+
+  it("Should validate miner fee", () => {
+    const chain = new MockChain();
+    const alice = chain.newParty("Alice");
+    alice.addBalance({ nanoergs: 10000000n });
+
+    // Transaction without fee
+    const unsignedTransaction = new TransactionBuilder(chain.height)
+      .from(alice.utxos)
+      .to(new OutputBuilder(SAFE_MIN_BOX_VALUE, alice.address))
+      .sendChangeTo(alice.address)
+      .build();
+
+    // Should pass but with warning (logged if log: true)
+    const consoleMock = vi.spyOn(console, "log").mockImplementationOnce(() => {});
+
+    expect(
+      chain.execute(unsignedTransaction, { signers: [alice], log: true })
+    ).to.be.true;
+
+    expect(consoleMock).toHaveBeenCalledWith(
+      expect.stringContaining("No miner fee box found")
+    );
+
+    consoleMock.mockRestore();
+  });
+
+  it("Should allow disabling checks", () => {
+    const chain = new MockChain();
+    const alice = chain.newParty("Alice");
+    alice.addBalance({ nanoergs: 10000000n });
+
+    const unsignedTransaction = new TransactionBuilder(chain.height)
+      .from(alice.utxos)
+      .to(new OutputBuilder("100", alice.address)) // Too small value
+      .sendChangeTo(alice.address)
+      .build();
+
+    // Should pass when checks are disabled
+    expect(
+      chain.execute(unsignedTransaction, { signers: [alice], checks: false })
+    ).to.be.true;
+  });
+
+  it("Should support custom fee trees", () => {
+    const chain = new MockChain();
+    const alice = chain.newParty("Alice");
+    const bob = chain.newParty("Bob"); // Create another party to use their ErgoTree
+    alice.addBalance({ nanoergs: 10000000n });
+
+    // Use Bob's ErgoTree as a custom fee contract
+    const customFeeTree = bob.ergoTree;
+
+    const unsignedTransaction = new TransactionBuilder(chain.height)
+      .from(alice.utxos)
+      .to(new OutputBuilder(SAFE_MIN_BOX_VALUE, alice.address))
+      .to(new OutputBuilder(RECOMMENDED_MIN_FEE_VALUE, customFeeTree)) // Custom fee box
+      .sendChangeTo(alice.address)
+      .build();
+
+    // Should pass with custom fee tree
+    expect(
+      chain.execute(unsignedTransaction, { 
+        signers: [alice],
+        checks: { customFeeErgoTrees: [customFeeTree] }
+      })
+    ).to.be.true;
+  });
+});

packages/mock-chain/src/mockChain.ts

@@ -15,6 +15,7 @@ import { printDiff } from "./balancePrinting";
 import { BLOCKCHAIN_PARAMETERS, execute } from "./execution";
 import { mockBlockchainStateContext } from "./objectMocking";
 import { KeyedMockChainParty, type MockChainParty, NonKeyedMockChainParty } from "./party";
+import { type TransactionCheckOptions, validateTransaction } from "./transactionChecks";
 
 const BLOCK_TIME_MS = 120000;
 const DEFAULT_HEIGHT = 1;
@@ -36,6 +37,7 @@ export type TransactionExecutionOptions = {
   signers?: KeyedMockChainParty[];
   throw?: boolean;
   log?: boolean;
+  checks?: TransactionCheckOptions | false;
 };
 
 export type MockChainOptions = {
@@ -178,6 +180,36 @@ export class MockChain {
         ? unsignedTransaction.toEIP12Object()
         : unsignedTransaction;
 
+    // Perform transaction validation checks if enabled (default is to run checks unless explicitly disabled)
+    if (options?.checks !== false) {
+      const validationResult = validateTransaction(
+        txObject,
+        this.#tip.parameters,
+        options?.checks
+      );
+
+      if (options?.log) {
+        // Log warnings
+        for (const warning of validationResult.warnings) {
+          log(pc.yellow(`${pc.bgYellow(pc.bold(" Warning "))} ${warning}`));
+        }
+
+        // Log errors
+        for (const error of validationResult.errors) {
+          log(pc.red(`${pc.bgRed(pc.bold(" Check Error "))} ${error}`));
+        }
+      }
+
+      if (!validationResult.success) {
+        if (options?.throw !== false) {
+          throw new Error(
+            `Transaction validation failed:\n${validationResult.errors.join("\n")}`
+          );
+        }
+        return false;
+      }
+    }
+
     const result = execute(txObject, keys, {
       context,
       baseCost,