Using Blocks API to handle ECE cart requests

[wjrosa]

Changes proposed in this Pull Request:

This PR expands the usage of the Blocks API (Cart API) to requests related to the cart itself: when adding items to the cart, retrieving items, removing, emptying, etc.

Testing instructions

• Checkout and build this branch on your test environment (tweak/using-blocks-api-to-process-cart-requests)
• Connect your Stripe account
• Enable express payment methods (Google Pay, Apple Pay, Link)
• As a shopper, purchase any products using the multiple ways available: product page, cart page (shortcode and block), checkout (shortcode and block), pay for order.
• Confirm all flows are still working correctly

---

• Covered with tests (or have a good reason not to test in description ☝️)
• Added changelog entry in both changelog.txt and readme.txt (or does not apply)
• Tested on mobile (or does not apply)

Post merge

• Added testing instructions to the Release Testing Instructions wiki page (or does not apply)
• Added the needs docs label (or does not apply)
• Included this PR in the Release Thread scope (or does not apply)

[annemirasol]

Great work! Found a shipping rates-related bug in shortcode cart/checkout:

1. Clear your cookies.
2. A a guest shopper, add a shippable product to cart.
3. Go to shortcode cart or shortcode checkout, and click Google Pay.
4. You will see this console error:

v3/?ver=3.0:1 Uncaught (in promise) IntegrationError: When `shippingAddressRequired` is true, you must specify `shippingRates`.

[wjrosa]

Great work! Found a shipping rates-related bug in shortcode cart/checkout:

1. Clear your cookies.
2. A a guest shopper, add a shippable product to cart.
3. Go to shortcode cart or shortcode checkout, and click Google Pay.
4. You will see this console error:

v3/?ver=3.0:1 Uncaught (in promise) IntegrationError: When `shippingAddressRequired` is true, you must specify `shippingRates`.

Good catch, Anne! I fixed it in 2af80a8 . Also added support for discounts.

[annemirasol]

Good catch, Anne! I fixed it in 2af80a8 . Also added support for discounts.

@wjrosa Weird, I am still getting the same error. I pulled the latest commits and re-built the source.

[wjrosa]

Good catch, Anne! I fixed it in 2af80a8 . Also added support for discounts.

@wjrosa Weird, I am still getting the same error. I pulled the latest commits and re-built the source.

Yeah, that's strange. I just tested again using the checkout, product, and cart pages. Anonymous and when logged in 🤔 . Did you try anything different from the steps you shared above?

[annemirasol]

Good catch, Anne! I fixed it in 2af80a8 . Also added support for discounts.

@wjrosa Weird, I am still getting the same error. I pulled the latest commits and re-built the source.

Yeah, that's strange. I just tested again using the checkout, product, and cart pages. Anonymous and when logged in 🤔 . Did you try anything different from the steps you shared above?

Same steps.

Do you have shipping zones defined? I have this:

[wjrosa]

f4c102a

Right! The issue was specific to free shipping. I was able to reproduce it using your setup and fixed it in f4c102a

[annemirasol]

f4c102a

Right! The issue was specific to free shipping. I was able to reproduce it using your setup and fixed it in f4c102a

Fix verified! Thanks!

Found a different issue, this time with variable products.

1. Go to the product page of a variable product, e.g. https://my-test-store.com/product/hoodie/
2. Select a variation, e.g. for Hoodie, "Yes" or "No" for the Logo variation.
3. Click Google Pay.
4. See console errors, and notice how the Google Pay modal no longer lets you choose any address.

Note that there is a PHP notice seen when loading a variable product page. I've filed the issue in #3815. This notice is also present in develop and does not seem to be affecting ability to purchase the item via express payment.

Edited to include screenshot of console errors:

[wjrosa]

f4c102a

Right! The issue was specific to free shipping. I was able to reproduce it using your setup and fixed it in f4c102a

Fix verified! Thanks!

Found a different issue, this time with variable products.

1. Go to the product page of a variable product, e.g. https://my-test-store.com/product/hoodie/
2. Select a variation, e.g. for Hoodie, "Yes" or "No" for the Logo variation.
3. Click Google Pay.
4. See console errors, and notice how the Google Pay modal no longer lets you choose any address.

Note that there is a PHP notice seen when loading a variable product page. I've filed the issue in #3815. This notice is also present in develop and does not seem to be affecting ability to purchase the item via express payment.

Edited to include screenshot of console errors:

Another great catch, Anne! 👍 Fixed it in 57a8a79. But it will just work with WC 9.7.0 since this part of the code was fixed here. So, upon merging this PR we may need to update the min. required WC version 🤔 (after waiting for the release).

[wjrosa]

@annemirasol to avoid blocking this PR, I decided to support the legacy version when variations are present in e123a0c. Let me know what you think 👀

[annemirasol]

to avoid blocking this PR, I decided to support the legacy version when variations are present in e123a0c. Let me know what you think 👀

Makes sense to me!

LGTM, no regression detected -- can complete purchases across different pages and using different payment methods! 🚢