fix(sampledEvaluateReductionTraceNodes): allow empty scripts to be debugged properly

Author: bitjson

src/lib/auth/templates/language/reduce.spec.ts

@@ -0,0 +1,69 @@
+// tslint:disable:no-expression-statement no-magic-numbers
+import test from 'ava';
+
+import {
+  AuthenticationInstruction,
+  createAuthenticationProgramExternalStateCommonEmpty,
+  createAuthenticationProgramStateCommon
+} from '../../auth';
+import {
+  AuthenticationProgramStateBCH,
+  instantiateVirtualMachineBCH,
+  OpcodesBCH
+} from '../../instruction-sets/bch/bch';
+
+import { sampledEvaluateReductionTraceNodes } from './reduce';
+
+const vmPromise = instantiateVirtualMachineBCH();
+const createCreateStateWithStack = <Opcodes, Errors>(stack: Uint8Array[]) => (
+  instructions: ReadonlyArray<AuthenticationInstruction<Opcodes>>
+) =>
+  createAuthenticationProgramStateCommon<Opcodes, Errors>(
+    instructions,
+    stack,
+    createAuthenticationProgramExternalStateCommonEmpty()
+  );
+const state = createCreateStateWithStack<
+  OpcodesBCH,
+  AuthenticationProgramStateBCH
+>([])([]) as AuthenticationProgramStateBCH;
+const getState = () => state;
+
+test('sampledEvaluateReductionTraceNodes: empty evaluation', async t => {
+  const vm = await vmPromise;
+  t.deepEqual(
+    sampledEvaluateReductionTraceNodes<
+      OpcodesBCH,
+      AuthenticationProgramStateBCH
+    >(
+      [
+        {
+          bytecode: Uint8Array.of(),
+          range: {
+            endColumn: 1,
+            endLineNumber: 1,
+            startColumn: 1,
+            startLineNumber: 1
+          }
+        }
+      ],
+      vm,
+      getState
+    ),
+    {
+      bytecode: Uint8Array.of(),
+      samples: [
+        {
+          range: {
+            endColumn: 1,
+            endLineNumber: 1,
+            startColumn: 1,
+            startLineNumber: 1
+          },
+          state
+        }
+      ],
+      success: true
+    }
+  );
+});

src/lib/auth/templates/language/reduce.ts

@@ -271,16 +271,20 @@ export const sampledEvaluateReductionTraceNodes = <
     getState
   );
   // tslint:disable-next-line: no-if-statement
-  if (parsed.success && evaluated.success && evaluated.samples.length > 0) {
-    const lastSample = evaluated.samples[evaluated.samples.length - 1];
+  if (parsed.success && evaluated.success) {
+    const samples =
+      evaluated.samples.length > 0
+        ? evaluated.samples
+        : [{ range: parsed.aggregations[0].range, state: getState([]) }];
+    const lastSample = samples[samples.length - 1];
     const lastStackItem = lastSample.state.stack[
       lastSample.state.stack.length - 1
     ] as Uint8Array | undefined;
     const evaluationResult =
       lastStackItem !== undefined ? lastStackItem.slice() : Uint8Array.of();
     return {
       bytecode: evaluationResult,
-      samples: evaluated.samples,
+      samples,
       success: true
     };
   }