WitnessTester.compute supports multiple output signals (#104)

* WitnessTester.compute supports multiple output signals

* Missed test circuit source

src/testers/witnessTester.ts

@@ -222,7 +222,8 @@ export class WitnessTester<IN extends readonly string[] = [], OUT extends readon
       // non-main signals have an additional `.` in them after `main.symbol`
       const signalDotCount = dotCount(signal) + 1; // +1 for the dot in `main.`
       const signalLength = signal.length + 5; // +5 for prefix `main.`
-      const symbolNames = Object.keys(this.symbols!).filter(s => signalDotCount === dotCount(s));
+      const symbolNames = Object.keys(this.symbols!).filter(s =>
+        s.startsWith(`main.${signal}`) && signalDotCount === dotCount(s));
 
       // get the symbol values from symbol names, ignoring `main.` prefix
       // the matched symbols must exactly equal the signal

tests/circuits/multiout.circom

@@ -0,0 +1,24 @@
+pragma circom 2.0.0;
+
+template Multiout(N) {
+  signal input a[N]; 
+  signal input b[N]; 
+  var newSize = N + N - 1;
+  signal output cOut[N];
+  signal output aOut[newSize];
+  signal output bOut[newSize];
+
+  var a1[newSize];
+  var b1[newSize];
+  var c1[N];
+  for(var i = 0; i<N; i++) {
+    a1[i] = a[i] * i;
+    b1[i] = b[i] * i;
+    c1[i] = a[i] * b[i];
+  }
+
+  cOut <== c1;
+  aOut <== a1;
+  bOut <== b1;
+}
+

tests/witnessTester.test.ts

@@ -4,14 +4,15 @@ import {prepareMultiplier} from './common';
 // TODO: add C tester
 
 describe('witness tester', () => {
+  let circomkit: Circomkit;
   let circuit: WitnessTester<['in'], ['out']>;
   const {
     circuit: {name, config, size, exact},
     signals,
   } = prepareMultiplier(4);
 
   beforeAll(async () => {
-    const circomkit = new Circomkit({
+    circomkit = new Circomkit({
       verbose: false,
       logLevel: 'silent',
       circuits: './tests/circuits.json',
@@ -46,6 +47,40 @@ describe('witness tester', () => {
     expect(output.out).toEqual(BigInt(signals.output.out));
   });
 
+  it('should compute correctly with multiple output signals', async () => {
+    const N = 167;
+    const newSize = N + N - 1;
+    const a = 2;
+    const b = 3;
+    const aOut = Array(newSize).fill(0).map((_, i) => BigInt(i < N ? a * i : 0));
+    const bOut = Array(newSize).fill(0).map((_, i) => BigInt(i < N ? b * i : 0));
+    const cOut = Array(N).fill(BigInt(a * b));
+
+    const circuit2 = await circomkit.WitnessTester('multiout', {
+      file: 'multiout',
+      template: 'Multiout',
+      params: [N],
+    });
+
+    const input = {
+      a: Array(N).fill(a),
+      b: Array(N).fill(b),
+    };
+    const output = await circuit2.compute(input, ['aOut', 'bOut', 'cOut']);
+
+    expect(output).toHaveProperty('aOut');
+    expect(output).toHaveProperty('bOut');
+    expect(output).toHaveProperty('cOut');
+    expect(output.aOut).toHaveLength(newSize);
+    expect(output.bOut).toHaveLength(newSize);
+    expect(output.cOut).toHaveLength(N);
+    expect(output.aOut).toEqual(aOut);
+    expect(output.bOut).toEqual(bOut);
+    expect(output.cOut).toEqual(cOut);
+
+    await circuit2.expectPass(input, output);
+  });
+
   it('should read witness correctly', async () => {
     const witness = await circuit.calculateWitness(signals.input);
     const symbol = 'main.out';