fix(product-sync): fix matching variants

[junajan]

Summary

Fix how we match variants.

Description

Originally, we were matching variants in a single loop by comparing id, sku or key.
Because we used id as a primary matching condition, there was happening, that we matched variants with the same ids but with different skus which later failed due to a duplicate slug error.

For example when syncing these two products:

// existing product
{
	masterVariant: {
		id: 1,
		sku: "sku1"
	},
	variants: [{
		id: 2,
		sku: "sku3"
	}, {
		id: 3,
		sku: "sku2"
	}]
}
// and new product
{
	masterVariant: {
		id: 1,
		sku: "sku1"
	},
	variants: [{
		id: 2,
		sku: "sku2"
	}, {
		id: 3,
		sku: "sku3"
	}]
}

It would match variants using id and generate update actions:

[{
	action: "setSku",
	variantId: 2,
	sku: "sku2"
}, {
	action: "setSku",
	variantId: 3,
	sku: "sku3"
}]

Which would fail because we can't set sku2 to the first variant because it already exists. Therefore we should match by skus, then by keys and then, as a fallback, by id.

Todo

• Tests
  • Unit
  • Integration
  • Acceptance
• Documentation

[junajan]

Waiting for coverage reports - there is reported a degraded performance on coveralls.io status page - http://status.coveralls.io/

[butenkor]

Should not we change the order also here and here and here? I think it might be better to always use sku if defined and fallback on internal only when nothing else possible.

[junajan]

Hi @butenkor .. updated here c8afbe7

[coveralls]

Coverage increased (+0.01%) to 97.66% when pulling eb01715 on 271-fix-match-variants-by-sku-key-id-separately into d2dbb23 on master.