1const path = require("path");
 2const Fr = require("ffjavascript").bn128.Fr;
 3const Scalar = require("ffjavascript").Scalar;
 4const tester = require("circom").tester;
 5
 6function print(circuit, w, s) {
 7    console.log(s + ": " + w[circuit.getSignalIdx(s)]);
 8}
 9
10function getBits(v, n) {
11    const res = [];
12    for (let i=0; i<n; i++) {
13        if (Scalar.isOdd(Scalar.shr(v, i))) {
14            res.push(Fr.one);
15        } else {
16            res.push(Fr.zero);
17        }
18    }
19    return res;
20}
21
22const q = Scalar.fromString("21888242871839275222246405745257275088548364400416034343698204186575808495617");
23
24describe("Sign test", function() {
25    let circuit;
26    this.timeout(100000);
27
28    before( async() => {
29        circuit = await tester(path.join(__dirname, "circuits", "sign_test.circom"));
30    });
31
32    it("Sign of 0", async () => {
33        const inp = getBits(Scalar.e(0), 254);
34        const w = await circuit.calculateWitness({in: inp}, true);
35
36        await circuit.assertOut(w, {sign: 0});
37    });
38
39    it("Sign of 3", async () => {
40        const inp = getBits(Scalar.e(3), 254);
41        const w = await circuit.calculateWitness({in: inp}, true);
42
43        await circuit.assertOut(w, {sign: 0});
44    });
45
46    it("Sign of q/2", async () => {
47        const inp = getBits(Scalar.shr(q, 1), 254);
48        const w = await circuit.calculateWitness({in: inp}, true);
49
50        await circuit.assertOut(w, {sign: 0});
51    });
52
53    it("Sign of q/2+1", async () => {
54        const inp = getBits(Scalar.add(Scalar.shr(q, 1), 1) , 254);
55        const w = await circuit.calculateWitness({in: inp}, true);
56
57        await circuit.assertOut(w, {sign: 1});
58    });
59
60    it("Sign of q-1", async () => {
61        const inp = getBits(Scalar.sub(q, 1), 254);
62        const w = await circuit.calculateWitness({in: inp}, true);
63
64        await circuit.assertOut(w, {sign: 1});
65    });
66
67    it("Sign of q", async () => {
68        const inp = getBits(q, 254);
69        const w = await circuit.calculateWitness({in: inp}, true);
70
71        await circuit.assertOut(w, {sign: 1});
72    });
73
74    it("Sign of all ones", async () => {
75        const inp = getBits(Scalar.sub(Scalar.shl(1,254),1), 254);
76        const w = await circuit.calculateWitness({in: inp}, true);
77
78        await circuit.assertOut(w, {sign: 1});
79    });
80});