Add testing notes

Author: Aljullu

docs/testing/releases/420.md

@@ -0,0 +1,21 @@
+## Testing notes and ZIP for release 4.2.0
+
+Zip file for testing: [woocommerce-gutenberg-products-block.zip](https://github.com/woocommerce/woocommerce-gutenberg-products-block/files/5769544/woocommerce-gutenberg-products-block.zip)
+
+## Feature plugin and package inclusion in WooCommerce core
+
+### SearchListControl styles cleanup ([#3604](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/3604))
+
+1. Add a Products by Attribute block in a page or post.
+2. Select some attributes and verify there are no visual regressions.
+3. Test it also with WP 5.4 + WC 4.3 (our oldest supported versions).
+
+## Feature plugin only
+
+### Convert saved payment methods token to a string ([#3627](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/3627))
+
+1. Install and enable WooCommerce Stripe Payment Gateway.
+2. With a new user, go to My Account > Payment Methods and add a new payment method.
+3. Add a product to your cart and go to the checkout page.
+4. Fill the details but keep the payment method as the saved card you added in step 2.
+5. Try to make a purchase and verify it completes successfully and no error is shown.

docs/testing/releases/README.md

@@ -19,3 +19,4 @@ Every release includes specific testing instructions for new features and bug fi
 - [3.9.0](./390.md)
 - [4.0.0](./400.md)
 - [4.1.0](./410.md)
+- [4.2.0](./420.md)