Merge pull request #23 from Terran-One/feat/time-travel

Query Time Travel

Author: Kiruse

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@terran-one/cw-simulate",
-  "version": "2.6.0",
+  "version": "2.6.1",
   "description": "Mock blockchain environment for simulating CosmWasm interactions",
   "main": "dist/index.js",
   "typings": "dist/index.d.ts",

src/modules/wasm.spec.ts

@@ -509,4 +509,40 @@ describe('Query', () => {
       admin: null,
     });
   });
+  
+  it('time travel', async () => {
+    const queryMsg = {
+      get_buffer: {},
+    };
+    
+    const traces: TraceLog[] = [];
+    await testContract.execute(
+      info.sender,
+      exec.run(
+        cmd.msg(exec.push('M1')),
+        cmd.msg(exec.push('M2')),
+        cmd.msg(exec.push('M3')),
+      ),
+      [],
+      traces,
+    );
+    
+    await testContract.execute(
+      info.sender,
+      exec.run(
+        cmd.msg(exec.push('M4')),
+      ),
+      [],
+      traces,
+    );
+    
+    expect(app.wasm.queryTrace(traces[0], queryMsg).val).toMatchObject({
+      buffer: ['M1', 'M2', 'M3'],
+    });
+    // IMPORTANT: `queryTrace` temporarily alters the backend a VM uses
+    // so we test here that it resets it
+    expect(app.wasm.query(testContract.address, queryMsg).val).toMatchObject({
+      buffer: ['M1', 'M2', 'M3', 'M4'],
+    });
+  });
 });

src/modules/wasm.ts

@@ -119,8 +119,8 @@ export class WasmModule {
     );
   }
 
-  getContractStorage(contractAddress: string) {
-    const existing = this.chain.store.getIn([
+  getContractStorage(contractAddress: string, storage = this.chain.store) {
+    const existing = storage.getIn([
       'wasm',
       'contractStorage',
       contractAddress,
@@ -135,8 +135,8 @@ export class WasmModule {
     );
   }
 
-  getCodeInfo(codeId: number): CodeInfo {
-    return this.chain.store.getIn(['wasm', 'codes', codeId]) as CodeInfo;
+  getCodeInfo(codeId: number, storage = this.chain.store): CodeInfo {
+    return storage.getIn(['wasm', 'codes', codeId]) as CodeInfo;
   }
 
   setContractInfo(contractAddress: string, contractInfo: ContractInfo) {
@@ -146,8 +146,8 @@ export class WasmModule {
     );
   }
 
-  getContractInfo(contractAddress: string) {
-    return this.chain.store.getIn([
+  getContractInfo(contractAddress: string, storage = this.chain.store) {
+    return storage.getIn([
       'wasm',
       'contracts',
       contractAddress,
@@ -637,6 +637,31 @@ export class WasmModule {
     return fromRustResult(vm.query(env, queryMsg).json as RustResult<string>)
       .andThen(v => Ok(fromBinary(v)));
   }
+  
+  queryTrace(
+    trace: TraceLog,
+    queryMsg: any,
+  ): Result<any, string> {
+    let { contractAddress, storeSnapshot } = trace;
+    let vm = this.vms[contractAddress];
+    if (!vm) throw new Error(`No VM for contract ${contractAddress}`);
+    
+    // time travel
+    const currBackend = vm.backend;
+    const storage = new BasicKVIterStorage(this.getContractStorage(contractAddress, storeSnapshot));
+    vm.backend = {
+      ...vm.backend,
+      storage,
+    };
+    
+    try {
+      return this.query(contractAddress, queryMsg);
+    }
+    // reset time travel
+    finally {
+      vm.backend = currBackend;
+    }
+  }
 
   buildAppResponse(
     contract: string,