Support JSON debugging output

test/multiplier2.js

@@ -18,7 +18,11 @@ describe("Simple test", function () {
         const circuit = await wasm_tester(
 	    path.join(__dirname, "Multiplier2.circom")
 	);
-        const w = await circuit.calculateWitness({a: 2, b: 4});
+        const a = 2;
+        const b = 4;
+        const w = await circuit.calculateWitness({a, b});
+        const signals = await circuit.getJSONOutput('main', w);
+        assert(signals.main.c == BigInt(a * b));
         await circuit.checkConstraints(w);
     });
 
@@ -28,7 +32,11 @@ describe("Simple test", function () {
 	    { output : path.join(__dirname),
 	    }
 	);
-        const w = await circuit.calculateWitness({a: 2, b: 4});
+        const a = 2;
+        const b = 4;
+        const w = await circuit.calculateWitness({a, b});
+        const signals = await circuit.getJSONOutput('main', w);
+        assert(signals.main.c == BigInt(a * b));
         await circuit.checkConstraints(w);
     });
 
@@ -39,7 +47,12 @@ describe("Simple test", function () {
 	      recompile : false,
 	    }
 	);
-        const w = await circuit.calculateWitness({a: 6, b: 3});
+        const a = 6;
+        const b = 3;
+        const w = await circuit.calculateWitness({a, b});
+        const signals = await circuit.getJSONOutput('main', w);
+        assert(signals.main.c == BigInt(a * b));
+
         await circuit.checkConstraints(w);
 
     });

wasm/tester.js

@@ -2,6 +2,7 @@ const chai = require("chai");
 const assert = chai.assert;
 
 const fs = require("fs");
+const readline = require('readline')
 var tmp = require("tmp-promise");
 const path = require("path");
 
@@ -213,6 +214,35 @@ class WasmTester {
         }
     }
 
+    async searchSymbols(regex) {
+        return new Promise((resolve, reject) => {
+            const filePath = path.join(this.dir, this.baseName + ".sym");
+
+            const rl = readline.createInterface({
+                input: fs.createReadStream(filePath),
+                crlfDelay: Infinity
+            });
+
+            const matches = [];
+            rl.on('line', (line) => {
+                if (regex.test(line)) {
+                    matches.push(line);
+                }
+            });
+
+            rl.on('close', () => {
+                resolve(matches);
+            });
+        });
+    }
+
+    async getJSONOutput(signalName, witness) {
+        //create regex using signalName
+        const regex = new RegExp(`\.${signalName}[\[|\.]`)
+        const symbols = await this.searchSymbols(regex);
+        return createObject(symbols, witness);
+    }
+
 }
 
 function version_to_list ( v ) {
@@ -236,3 +266,71 @@ async function compiler_above_version(v) {
     vlist = version_to_list(v);
     return check_versions ( compiler_version, vlist );
 }
+
+function splitString(input) {
+    var regex = /\b[a-zA-Z_]+|\[[\d]+\]/g;
+    return input.match(regex);
+}
+
+function createObject(symbols, values) {
+    function recursiveCreate(parts, currentObj, value) {
+        var part = parts.shift();
+        var next = parts[0];
+
+        var parentObj = currentObj;
+
+        if (part && part.charAt(0) === "[") {
+            var arrayIndex = parseInt(part.slice(1, -1));
+
+            if (next && next.charAt(0) === "[") {
+                var array = currentObj[arrayIndex] || [];
+                currentObj[arrayIndex] = array;
+                currentObj = array;
+            } else {
+                var obj = currentObj[arrayIndex] || {};
+                currentObj[arrayIndex] = obj;
+                currentObj = obj;
+            }
+        } else if (next && next.charAt(0) === "[") {
+            var key = part;
+            var array = currentObj[key] || [];
+            var arrayIndex = parseInt(next.slice(1, -1));
+
+            currentObj[key] = array;
+            currentObj = array;
+        } else {
+            var obj = currentObj[part] || {};
+
+            currentObj[part] = obj;
+            currentObj = obj;
+        }
+
+        if (!next) {
+            if (part.charAt(0) === "[") {
+                var arrayIndex = parseInt(part.slice(1, -1));
+                parentObj[arrayIndex] = value;
+            } else {
+                parentObj[part] = value;
+            }
+            currentObj = parentObj;
+        }
+
+        if (parts.length > 0) {
+            return recursiveCreate(parts, currentObj, value);
+        } else {
+            return currentObj;
+        }
+    }
+
+    var output = {};
+
+    for (var i = 0; i < symbols.length; i++) {
+        var symbol = symbols[i];
+        var [, valueIndex, , path] = symbol.split(",");
+        var parts = splitString(path);
+        var value = values[valueIndex];
+        recursiveCreate(parts, output, value);
+    }
+
+    return output;
+}