Bug with MoveBefore

[jeemyeong]

What happened:

Cannot pass test code

Yorkie Can handle concurrent moveBefore operations FAILED
        AssertionError: expected '{"k1":[1,2,0]}' to equal '{"k1":[2,1,0]}'

What you expected to happen:

PASSED

How to reproduce it (as minimally and precisely as possible):
When I edit test code like below

      d1.update((root) => {
        const next = root['k1'].getElementByIndex(0);
        const item = root['k1'].getElementByIndex(2);
        root['k1'].moveBefore(next.getID(), item.getID());
        assert.equal('{"k1":[2,0,1]}', root.toJSON());
      });
      await c1.sync();
      d1.update((root) => {
        const next = root['k1'].getElementByIndex(0);
        const item = root['k1'].getElementByIndex(2);
        root['k1'].moveBefore(next.getID(), item.getID());
        assert.equal('{"k1":[1,2,0]}', root.toJSON());
      });

from

yorkie-js-sdk/test/yorkie_test.ts

Lines 331 to 357 in 07f71fe

	it('Can handle concurrent moveBefore operations', async function () {
	await withTwoClientsAndDocuments(async (c1, d1, c2, d2) => {
	d1.update((root) => {
	root['k1'] = [0, 1, 2];
	assert.equal('{"k1":[0,1,2]}', root.toJSON());
	});
	await c1.sync();
	await c2.sync();
	assert.equal(d1.toJSON(), d2.toJSON());
	d1.update((root) => {
	const next = root['k1'].getElementByIndex(0);
	const item = root['k1'].getElementByIndex(2);
	root['k1'].moveBefore(next.getID(), item.getID());
	assert.equal('{"k1":[2,0,1]}', root.toJSON());
	});
	d2.update((root) => {
	const next = root['k1'].getElementByIndex(1);
	const item = root['k1'].getElementByIndex(2);
	root['k1'].moveBefore(next.getID(), item.getID());
	assert.equal('{"k1":[0,2,1]}', root.toJSON());
	});
	await c1.sync();
	await c2.sync();
	await c1.sync();
	}, this.test.title);
	});

Anything else we need to know?:

I am researching moveAfter functions and I cannot found the purpose of some codes.

yorkie-js-sdk/src/document/json/rga_tree_list.ts

Line 181 in 07f71fe

this.insertAfter(prevNode.getCreatedAt(), node.getValue());

yorkie-js-sdk/src/document/json/rga_tree_list.ts

Lines 148 to 149 in 07f71fe

	public insertAfter(prevCreatedAt: TimeTicket, value: JSONElement): void {
	const prevNode = this.findByCreatedAt(prevCreatedAt, value.getCreatedAt());

When I was debugging some codes,
prevNode from const prevNode = this.findByCreatedAt(prevCreatedAt, value.getCreatedAt()); was not same with as I expected.

I cannot catch the purpose of this code.

yorkie-js-sdk/src/document/json/rga_tree_list.ts

Lines 120 to 134 in 07f71fe

	private findByCreatedAt(
	prevCreatedAt: TimeTicket,
	createdAt: TimeTicket,
	): RGATreeListNode {
	let node = this.nodeMapByCreatedAt.get(prevCreatedAt.toIDString());
	if (!node) {
	logger.fatal(`cant find the given node: ${prevCreatedAt.toIDString()}`);
	}
	while (node.getNext() && node.getNext().getCreatedAt().after(createdAt)) {
	node = node.getNext();
	}
	return node;
	}

Environment:

• Operating system: (Mac OS 10.15.6)
• Browser and version: Chrome Headless 85.0.4183.83
• Yorkie version (use yorkie version): 0.0.12
• Yorkie JS SDK version: 0.0.9

[jeemyeong]

I caught the purposed of the findByCreatedAt method. (which has two arguments).

I will try to fix this issue.