o1js/src/lib/provable/test/dynamic-array.unit-test.ts

TypeScript framework for zk-SNARKs and zkApps

import { UInt8 } from '../int.js';
import { Field } from '../field.js';
import { ZkProgram } from '../../proof-system/zkprogram.js';
import { DynamicArray } from '../dynamic-array.js';
import { assert } from '../gadgets/common.js';
import { Provable } from '../provable.js';

// Out-of-circuit checks of dynamic arrays
{
  function expectThrows(fn: () => void | Promise<void>, msg: string) {
    let threw = false;
    try {
      fn();
    } catch {
      threw = true;
    }
    assert(threw, msg);
  }

  // Define classes of dynamic arrays for specific provable types
  class Bytestring extends DynamicArray(UInt8, { capacity: 8 }) {}

  // Test the constructor with different initializations
  let fromArray = new Bytestring([new UInt8(1), new UInt8(2), new UInt8(3)]);
  assert(fromArray.length.equals(new Field(3)));
  assert(fromArray.capacity === 8);

  let fromLength = new Bytestring(undefined, new Field(0));
  assert(fromLength.length.equals(new Field(0)));
  assert(fromLength.capacity === 8);

  let fromArrayLength = new Bytestring(
    [new UInt8(1), new UInt8(2), new UInt8(3), new UInt8(0)],
    new Field(3)
  );
  assert(fromArrayLength.length.equals(new Field(3)));
  assert(fromArrayLength.capacity === 8);
  assert(fromArrayLength.get(new Field(0)).value.equals(new Field(1)));
  assert(fromArrayLength.get(new Field(1)).value.equals(new Field(2)));
  assert(fromArrayLength.get(new Field(2)).value.equals(new Field(3)));
  fromArrayLength.getOption(new Field(3)).assertNone();

  // Copy into new dynamic arrays
  let copySame = fromArray.copy();
  assert(copySame.length.equals(fromArray.length));
  assert(copySame.capacity === fromArray.capacity);
  assert(copySame.get(new Field(0)).value.equals(new Field(1)));
  assert(copySame.get(new Field(1)).value.equals(new Field(2)));
  assert(copySame.get(new Field(2)).value.equals(new Field(3)));
  for (let i = 3; i < 8; i++) {
    copySame.getOption(new Field(i)).assertNone();
  }

  // Initialize an empty dynamic array
  let bytes = new Bytestring();

  // Initialization should produce right capacity and length
  assert(bytes.capacity === 8);
  assert(bytes.length.equals(new Field(0)));

  // Pushing elements should increase length but keep capacity
  bytes.push(new UInt8(1));
  assert(bytes.length.equals(new Field(1)));
  assert(bytes.capacity === 8);
  assert(bytes.get(new Field(0)).value.equals(new Field(1)));

  // Popping elements should decrease length but keep capacity
  bytes.pop();
  assert(bytes.length.equals(new Field(0)));
  assert(bytes.capacity === 8);

  // Cannot push more elements than the capacity
  for (let i = 0; i < 8; i++) {
    bytes.push(new UInt8(i));
  }
  expectThrows(() => {
    bytes.push(new UInt8(8));
  }, 'Cannot push more elements than the capacity');

  // Popping zero elements should not change the array
  bytes.pop(new Field(0));

  // Popping multiple elements should decrease length by the specified amount
  assert(bytes.length.equals(new Field(8)));
  bytes.pop(new Field(8));
  assert(bytes.length.equals(new Field(0)));

  // Cannot pop more elements than the current length
  expectThrows(() => {
    bytes.pop();
  }, 'Cannot pop more elements than the length');

  // Empty behaviour should be correct
  assert(bytes.isEmpty().toBoolean());
  bytes.push(new UInt8(1));
  assert(!bytes.isEmpty().toBoolean());

  // Getters and setters for existing positions
  assert(bytes.get(new Field(0)).value.equals(new Field(1)));
  bytes.set(new Field(0), new UInt8(2));
  assert(bytes.get(new Field(0)).value.equals(new Field(2)));
  assert(bytes.length.equals(new Field(1)));

  // getOption returns None for out-of-bounds and Some for in-bounds index
  bytes.getOption(new Field(0)).assertSome();
  bytes.getOption(new Field(1)).assertNone();

  // Error if getting out-of-bounds index
  expectThrows(() => {
    bytes.get(new Field(1));
  }, 'Cannot get out-of-bounds index');

  // Error if setting out-of-bounds index
  expectThrows(() => {
    bytes.set(new Field(1), new UInt8(3));
  }, 'Cannot set out-of-bounds index');

  // Growing capacity should work correctly
  let longerArray = bytes.growCapacityTo(10);
  assert(longerArray.capacity === 10);
  assert(longerArray.length.equals(new Field(1)));

  // Growing capacity by increment should work correctly
  let sameArray = longerArray.growCapacityBy(0);
  assert(sameArray.capacity === 10);
  assert(sameArray.length.equals(new Field(1)));
  let otherArray = bytes.growCapacityBy(2);
  assert(otherArray.capacity === 10);
  assert(otherArray.length.equals(new Field(1)));

  // Mapping over elements should work correctly
  bytes.push(new UInt8(1));
  bytes.push(new UInt8(0));
  let mapped = bytes.map(UInt8, (value) => value.add(UInt8.from(1)));
  assert(mapped.get(new Field(0)).value.equals(new Field(3)));
  assert(mapped.get(new Field(1)).value.equals(new Field(2)));
  assert(mapped.get(new Field(2)).value.equals(new Field(1)));

  // Reinstantiating the array for further tests
  bytes = new Bytestring();
  for (let i = 0; i < 8; i++) {
    bytes.push(new UInt8(10 + i));
  }

  // Shifting left 0 positions does not change the array
  bytes.shiftLeft(new Field(0));
  assert(bytes.length.equals(new Field(8)));
  for (let i = 0; i < 8; i++) {
    assert(bytes.get(new Field(i)).value.equals(new Field(10 + i)));
  }

  // Checks shifting left elements
  bytes.shiftLeft(new Field(3));
  assert(bytes.length.equals(new Field(5)));
  assert(bytes.get(new Field(0)).value.equals(new Field(13)));
  assert(bytes.get(new Field(1)).value.equals(new Field(14)));
  assert(bytes.get(new Field(2)).value.equals(new Field(15)));
  assert(bytes.get(new Field(3)).value.equals(new Field(16)));
  assert(bytes.get(new Field(4)).value.equals(new Field(17)));
  bytes.getOption(new Field(5)).assertNone();
  bytes.getOption(new Field(6)).assertNone();
  bytes.getOption(new Field(7)).assertNone();

  // Shift left by the length
  bytes.shiftLeft(bytes.length);
  assert(bytes.length.equals(new Field(0)));

  // Cannot shift left more elements than the current length
  expectThrows(() => {
    bytes.shiftLeft(new Field(1));
  }, 'Cannot shift left further than the length');

  // Reinstantiating the array for further tests with space for shifting
  bytes = new Bytestring();
  for (let i = 0; i < 5; i++) {
    bytes.push(new UInt8(10 + i));
  }

  // Shifting right 0 positions does not change the array
  bytes.shiftRight(new Field(0));
  assert(bytes.length.equals(new Field(5)));
  for (let i = 0; i < 5; i++) {
    assert(bytes.get(new Field(i)).value.equals(new Field(10 + i)));
  }

  // Checks shifting right elements
  bytes.shiftRight(new Field(2));
  assert(bytes.length.equals(new Field(7)));
  let NULL = new Field(0);
  assert(bytes.get(new Field(0)).value.equals(NULL));
  assert(bytes.get(new Field(1)).value.equals(NULL));
  assert(bytes.get(new Field(2)).value.equals(new Field(10)));
  assert(bytes.get(new Field(3)).value.equals(new Field(11)));
  assert(bytes.get(new Field(4)).value.equals(new Field(12)));
  assert(bytes.get(new Field(5)).value.equals(new Field(13)));
  assert(bytes.get(new Field(6)).value.equals(new Field(14)));
  bytes.getOption(new Field(7)).assertNone();

  // Cannot shift right more elements than the capacity
  expectThrows(() => {
    bytes.shiftRight(new Field(2));
  }, 'Cannot shift right above capacity');

  // Slicing [0, length) should return the same array
  bytes = new Bytestring();
  for (let i = 0; i < 4; i++) {
    bytes.push(new UInt8(10 + i));
  }
  let whole = bytes.slice(new Field(0), bytes.length);
  assert(bytes.length.equals(new Field(4)));
  assert(whole.length.equals(bytes.length));
  for (let i = 0; i < 4; i++) {
    assert(whole.get(new Field(i)).value.equals(bytes.get(new Field(i)).value));
  }

  // Slicing [0, 0) should return an empty array
  let empty = bytes.slice(new Field(0), new Field(0));
  assert(bytes.length.equals(new Field(4)));
  assert(empty.length.equals(new Field(0)));

  // Slicing [0, 1) should return an array with the first element
  let first = bytes.slice(new Field(0), new Field(1));
  assert(bytes.length.equals(new Field(4)));
  assert(first.length.equals(new Field(1)));
  assert(first.get(new Field(0)).value.equals(bytes.get(new Field(0)).value));

  // Slicing intermediate positions should work correctly
  let intermediate = bytes.slice(new Field(1), new Field(3));
  assert(intermediate.length.equals(new Field(2)));
  assert(intermediate.get(new Field(0)).value.equals(bytes.get(new Field(1)).value));
  assert(intermediate.get(new Field(1)).value.equals(bytes.get(new Field(2)).value));

  // Cannot slice out-of-bounds positions
  expectThrows(() => {
    bytes.slice(new Field(1), new Field(5));
  }, 'Cannot slice out-of-bounds positions');

  // Cannot slice with end position smaller than start position
  expectThrows(() => {
    bytes.slice(new Field(2), new Field(1));
  }, 'Cannot slice with end position smaller than start position');

  // Concatenate two empty arrays gives an empty array
  let emptyLeft = new Bytestring();
  let emptyRight = new Bytestring();
  let emptyConcat = emptyLeft.concat(emptyRight);
  assert(emptyConcat.length.equals(new Field(0)));
  assert(emptyConcat.capacity === 16);

  // Concatenate an empty array with a non-empty array gives the non-empty array
  let right = new Bytestring([new UInt8(10), new UInt8(20), new UInt8(30)]);
  let nonEmptyRight = emptyLeft.concat(right);
  assert(nonEmptyRight.length.equals(new Field(3)));
  assert(nonEmptyRight.capacity === 16);
  for (let i = 0; i < 3; i++) {
    assert(nonEmptyRight.get(new Field(i)).value.equals(right.get(new Field(i)).value));
  }

  // Concatenate a non-empty array with an empty array gives the non-empty array
  let left = new Bytestring([
    new UInt8(1),
    new UInt8(2),
    new UInt8(3),
    new UInt8(4),
    new UInt8(5),
    new UInt8(6),
    new UInt8(7),
    new UInt8(8),
  ]);
  let nonEmptyLeft = left.concat(emptyRight);
  assert(nonEmptyLeft.length.equals(new Field(8)));
  assert(nonEmptyLeft.capacity === 16);
  for (let i = 0; i < 8; i++) {
    assert(nonEmptyLeft.get(new Field(i)).value.equals(left.get(new Field(i)).value));
  }

  // Concatenate two non-empty arrays gives the concatenation of both
  let both = left.concat(right);
  assert(both.length.equals(new Field(11)));
  assert(both.capacity === 16);
  for (let i = 0; i < 8; i++) {
    assert(both.get(new Field(i)).value.equals(left.get(new Field(i)).value));
  }
  for (let i = 0; i < 3; i++) {
    assert(both.get(new Field(i + 8)).value.equals(right.get(new Field(i)).value));
  }

  // Inserting elements at the beginning of the array
  bytes = new Bytestring([new UInt8(2), new UInt8(3), new UInt8(4), new UInt8(6), new UInt8(7)]);
  bytes.insert(new Field(0), new UInt8(1));
  assert(bytes.length.equals(new Field(6)));
  assert(bytes.get(new Field(0)).value.equals(new Field(1)));
  assert(bytes.get(new Field(1)).value.equals(new Field(2)));
  assert(bytes.get(new Field(2)).value.equals(new Field(3)));
  assert(bytes.get(new Field(3)).value.equals(new Field(4)));
  assert(bytes.get(new Field(4)).value.equals(new Field(6)));
  assert(bytes.get(new Field(5)).value.equals(new Field(7)));

  // Inserting elements at the end of the array
  bytes.insert(bytes.length, new UInt8(8));
  assert(bytes.length.equals(new Field(7)));
  assert(bytes.get(new Field(0)).value.equals(new Field(1)));
  assert(bytes.get(new Field(1)).value.equals(new Field(2)));
  assert(bytes.get(new Field(2)).value.equals(new Field(3)));
  assert(bytes.get(new Field(3)).value.equals(new Field(4)));
  assert(bytes.get(new Field(4)).value.equals(new Field(6)));
  assert(bytes.get(new Field(5)).value.equals(new Field(7)));
  assert(bytes.get(new Field(6)).value.equals(new Field(8)));

  // Inserting elements in the middle of the array
  bytes.insert(new Field(4), new UInt8(5));
  assert(bytes.length.equals(new Field(8)));
  for (let i = 0; i < 8; i++) {
    assert(bytes.get(new Field(i)).value.equals(new Field(i + 1)));
  }

  // Cannot insert elements exceeding capacity
  expectThrows(() => {
    bytes.insert(new Field(1), new UInt8(0));
  }, 'Cannot insert above capacity');

  // Cannot insert elements out-of-bounds
  bytes = new Bytestring([new UInt8(1), new UInt8(2), new UInt8(3)]);
  expectThrows(() => {
    bytes.insert(new Field(4), new UInt8(5));
  }, 'Cannot insert out-of-bounds');

  // Checking inclusion of elements
  assert(bytes.includes(new UInt8(1)).toBoolean());
  assert(bytes.includes(new UInt8(20)).not().toBoolean());
}

// Using dynamic arrays as private input
{
  class Bytestring extends DynamicArray(UInt8, { capacity: 8 }) {}

  let AsPrivateInput = ZkProgram({
    name: 'dynamicarrays',
    methods: {
      pushAndPop: {
        privateInputs: [Bytestring, UInt8],
        async method(bytes: Bytestring, v: UInt8) {
          let last = bytes.length;
          bytes.push(v);
          assert(bytes.get(last).value.equals(v.value));
          bytes.pop(last);
          assert(bytes.isEmpty().not());
          bytes.pop();
          assert(bytes.isEmpty());
        },
      },
    },
  });

  await AsPrivateInput.compile();

  let bytes = new Bytestring([new UInt8(1), new UInt8(2), new UInt8(3)]);

  await AsPrivateInput.pushAndPop(bytes, UInt8.from(4));
}

// Provable behaviour
{
  class Bytestring extends DynamicArray(UInt8, { capacity: 8 }) {}

  await Provable.runAndCheck(() => {
    let b = Provable.witness(Bytestring, () => new Bytestring());
    b.push(UInt8.from(1));
  });
}

// In-circuit test for dynamic arrays
{
  let List = ZkProgram({
    name: 'dynamicarrays-circuit',
    methods: {
      incircuit: {
        privateInputs: [UInt8],
        async method(v0: UInt8) {
          // Define classes of dynamic arrays for specific provable types
          class Bytestring extends DynamicArray(UInt8, { capacity: 8 }) {}

          // Initialize an empty dynamic array
          let bytes = new Bytestring();

          // Pushing and popping elements
          bytes.push(v0);
          assert(bytes.get(new Field(0)).value.equals(v0.value));

          // Popping elements should decrease length but keep capacity
          bytes.pop();

          // Cannot push more elements than the capacity
          for (let i = 0; i < 8; i++) {
            bytes.push(v0.add(new UInt8(i)));
          }

          // Popping zero elements should not change the array
          bytes.pop(new Field(0));
          for (let i = 0; i < 8; i++) {
            assert(bytes.get(new Field(i)).value.equals(new Field(i).add(v0.value)));
          }

          // Popping multiple elements should decrease length by the specified amount
          bytes.pop(new Field(8));

          // Empty behaviour should be correct
          assert(bytes.isEmpty());
          bytes.push(v0);
          assert(bytes.isEmpty().not());

          // Getters and setters for existing positions
          bytes.set(new Field(0), v0.mul(new UInt8(2)));
          assert(bytes.get(new Field(0)).value.equals(new Field(2).mul(v0.value)));

          // getOption returns None for out-of-bounds and Some for in-bounds index
          bytes.getOption(new Field(0)).assertSome();
          bytes.getOption(new Field(1)).assertNone();

          // Growing capacity should work correctly
          let longerArray = bytes.growCapacityTo(10);

          // Growing capacity by increment should work correctly
          let sameArray = longerArray.growCapacityBy(0);
          let otherArray = bytes.growCapacityBy(2);

          assert(longerArray.get(new Field(0)).value.equals(sameArray.get(new Field(0)).value));
          assert(otherArray.get(new Field(0)).value.equals(bytes.get(new Field(0)).value));

          // Mapping over elements should work correctly
          bytes.push(v0.add(new UInt8(1)));
          bytes.push(v0.mul(new UInt8(0)));
          let mapped = bytes.map(UInt8, (value) => value.add(UInt8.from(1)));
          assert(
            mapped.get(new Field(0)).value.equals(v0.value.mul(new Field(2)).add(new Field(1)))
          );
          assert(mapped.get(new Field(1)).value.equals(v0.value.add(new Field(2))));
          assert(mapped.get(new Field(2)).value.equals(new Field(1)));

          // Reinstantiating the array for further tests
          bytes = new Bytestring();
          for (let i = 0; i < 8; i++) {
            bytes.push(v0.sub(new UInt8(i)));
          }

          // Shifting left 0 positions does not change the array
          bytes.shiftLeft(new Field(0));
          for (let i = 0; i < 8; i++) {
            assert(bytes.get(new Field(i)).value.equals(v0.value.sub(new Field(i))));
          }

          // Checks shifting left elements
          let shl = 3;
          bytes.shiftLeft(new Field(shl));
          for (let i = 0; i < 8 - shl; i++) {
            assert(bytes.get(new Field(i)).value.equals(v0.value.sub(new Field(i + shl))));
          }
          for (let i = 8 - shl; i < 8; i++) {
            bytes.getOption(new Field(i)).assertNone();
          }

          // Reinstantiating the array for further tests with space for shifting
          bytes = new Bytestring();
          for (let i = 0; i < 5; i++) {
            bytes.push(v0.add(new UInt8(10 + i)));
          }

          // Shifting right 0 positions does not change the array
          bytes.shiftRight(new Field(0));
          for (let i = 0; i < 5; i++) {
            assert(bytes.get(new Field(i)).value.equals(v0.value.add(new Field(10 + i))));
          }

          // Checks shifting right elements
          let shr = 2;
          bytes.shiftRight(new Field(shr));
          let NULL = new Field(0);
          for (let i = 0; i < shr; i++) {
            assert(bytes.get(new Field(i)).value.equals(NULL));
          }
          for (let i = shr; i < 7; i++) {
            assert(bytes.get(new Field(i)).value.equals(v0.value.add(new Field(10 + i - shr))));
          }
          bytes.getOption(new Field(7)).assertNone();

          // Slicing [0, length) should return the same array
          bytes = new Bytestring();
          for (let i = 0; i < 4; i++) {
            bytes.push(v0.add(new UInt8(i)));
          }
          let whole = bytes.slice(new Field(0), bytes.length);
          for (let i = 0; i < 4; i++) {
            assert(whole.get(new Field(i)).value.equals(bytes.get(new Field(i)).value));
          }

          // Slicing [0, 0) should return an empty array
          let empty = bytes.slice(new Field(0), new Field(0));
          assert(empty.isEmpty());

          // Slicing [0, 1) should return an array with the first element
          let first = bytes.slice(new Field(0), new Field(1));
          assert(first.get(new Field(0)).value.equals(bytes.get(new Field(0)).value));

          // Slicing intermediate positions should work correctly
          let intermediate = bytes.slice(new Field(1), new Field(3));
          assert(intermediate.get(new Field(0)).value.equals(bytes.get(new Field(1)).value));
          assert(intermediate.get(new Field(1)).value.equals(bytes.get(new Field(2)).value));

          // Concatenate two empty arrays gives an empty array
          let emptyLeft = new Bytestring();
          let emptyRight = new Bytestring();
          let emptyConcat = emptyLeft.concat(emptyRight);
          assert(emptyConcat.isEmpty());

          // Concatenate an empty array with a non-empty array gives the non-empty array
          let right = new Bytestring([new UInt8(10), new UInt8(20), new UInt8(30)]);
          let nonEmptyRight = emptyLeft.concat(right);
          for (let i = 0; i < 3; i++) {
            assert(nonEmptyRight.get(new Field(i)).value.equals(right.get(new Field(i)).value));
          }

          // Concatenate a non-empty array with an empty array gives the non-empty array
          let left = new Bytestring([
            new UInt8(1),
            new UInt8(2),
            new UInt8(3),
            new UInt8(4),
            new UInt8(5),
            new UInt8(6),
            new UInt8(7),
            new UInt8(8),
          ]);
          let nonEmptyLeft = left.concat(emptyRight);
          assert(nonEmptyLeft.capacity === 16);
          for (let i = 0; i < 8; i++) {
            assert(nonEmptyLeft.get(new Field(i)).value.equals(left.get(new Field(i)).value));
          }

          // Concatenate two non-empty arrays gives the concatenation of both
          let both = left.concat(right);
          assert(both.capacity === 16);
          for (let i = 0; i < 8; i++) {
            assert(both.get(new Field(i)).value.equals(left.get(new Field(i)).value));
          }
          for (let i = 0; i < 3; i++) {
            assert(both.get(new Field(i + 8)).value.equals(right.get(new Field(i)).value));
          }

          // Inserting elements at the beginning of the array
          bytes = new Bytestring([
            new UInt8(2),
            new UInt8(3),
            new UInt8(4),
            new UInt8(6),
            new UInt8(7),
          ]);
          bytes.insert(new Field(0), new UInt8(1));
          assert(bytes.get(new Field(0)).value.equals(new Field(1)));
          assert(bytes.get(new Field(1)).value.equals(new Field(2)));
          assert(bytes.get(new Field(2)).value.equals(new Field(3)));
          assert(bytes.get(new Field(3)).value.equals(new Field(4)));
          assert(bytes.get(new Field(4)).value.equals(new Field(6)));
          assert(bytes.get(new Field(5)).value.equals(new Field(7)));

          // Inserting elements at the end of the array
          bytes.insert(bytes.length, new UInt8(8));
          assert(bytes.get(new Field(0)).value.equals(new Field(1)));
          assert(bytes.get(new Field(1)).value.equals(new Field(2)));
          assert(bytes.get(new Field(2)).value.equals(new Field(3)));
          assert(bytes.get(new Field(3)).value.equals(new Field(4)));
          assert(bytes.get(new Field(4)).value.equals(new Field(6)));
          assert(bytes.get(new Field(5)).value.equals(new Field(7)));
          assert(bytes.get(new Field(6)).value.equals(new Field(8)));

          // Inserting elements in the middle of the array
          bytes.insert(new Field(4), new UInt8(5));
          for (let i = 0; i < 8; i++) {
            assert(bytes.get(new Field(i)).value.equals(new Field(i + 1)));
          }

          // Checking inclusion of elements
          assert(bytes.includes(new UInt8(1)));
          assert(bytes.includes(new UInt8(20)).not());

          // Reverse the array
          let reversed = bytes.reverse();
          for (let i = 0; i < 8; i++) {
            assert(reversed.get(new Field(i)).value.equals(new Field(8 - i)));
            // the original array is not modified
            assert(bytes.get(new Field(i)).value.equals(new Field(i + 1)));
          }
        },
      },
    },
  });

  await List.compile();

  let { proof } = await List.incircuit(new UInt8(100));
  let isValid = await List.verify(proof);
  assert(isValid, 'Proof for dynamic arrays should be verified');
}