Product Variations modifying cart quantities of other variations

[jdillman1989]

Prerequisites

• I have searched for similar issues in both open and closed tickets and cannot find a duplicate
• The issue still exists against the latest master branch of WooCommerce on Github (this is not the same version as on WordPress.org!)
• I have attempted to find the simplest possible steps to reproduce the issue
• I have included a failing test as a pull request (Optional)

Steps to reproduce the issue

1. Add a product variation to the cart by hitting a url such as /cart/?add-to-cart=92&variation_id=103
2. Add a different variation of the same product to the cart using the same method (example: /cart/?add-to-cart=92&variation_id=101)
3. When the new variation on the same product is added, the previous variation's quantity is increased by 1. (This continues as more variations of the same product are added to the cart)

Expected/actual behavior

When I follow those steps, I see...

The cart increases the quantity of the previous variation by 1, and displays the new variation.

I was expecting to see...

The cart should display the new variation only, not increase the quantities of any other products in the cart.

Isolating the problem

• This bug happens with only WooCommerce plugin active
• This bug happens with a default WordPress theme active, or Storefront
• I can reproduce this bug consistently using the steps above

WordPress Environment

``` ` ### WordPress Environment ###

Home URL: http://localhost/music-fts
Site URL: http://localhost/music-fts
WC Version: 3.2.5
Log Directory Writable: ✔
WP Version: 4.8.5
WP Multisite: –
WP Memory Limit: 13 GB
WP Debug Mode: –
WP Cron: ✔
Language: en_US

Server Environment

Server Info: Apache
PHP Version: 7.1.8
PHP Post Max Size: 3 GB
PHP Time Limit: 3000
PHP Max Input Vars: 1000
cURL Version: 7.52.1
OpenSSL/1.0.2j

SUHOSIN Installed: –
MySQL Version: 5.6.35
Max Upload Size: 3 GB
Default Timezone is UTC: ✔
fsockopen/cURL: ✔
SoapClient: ✔
DOMDocument: ✔
GZip: ✔
Multibyte String: ✔
Remote Post: ✔
Remote Get: ✔

Database

WC Database Version: 3.2.5
WC Database Prefix: wp_
MaxMind GeoIP Database: ❌ The MaxMind GeoIP Database does not exist - Geolocation will not function. You can download and install it manually from http://dev.maxmind.com/geoip/legacy/geolite/ to the path: . Scroll down to "Downloads" and download the "Binary / gzip" file next to "GeoLite Country". Please remember to uncompress GeoIP.dat.gz and upload the GeoIP.dat file only.
Total Database Size: 2.44MB
Database Data Size: 1.37MB
Database Index Size: 1.07MB
wp_woocommerce_sessions: Data: 0.02MB + Index: 0.02MB
wp_woocommerce_api_keys: Data: 0.02MB + Index: 0.03MB
wp_woocommerce_attribute_taxonomies: Data: 0.02MB + Index: 0.02MB
wp_woocommerce_downloadable_product_permissions: Data: 0.02MB + Index: 0.05MB
wp_woocommerce_order_items: Data: 0.02MB + Index: 0.02MB
wp_woocommerce_order_itemmeta: Data: 0.02MB + Index: 0.03MB
wp_woocommerce_tax_rates: Data: 0.02MB + Index: 0.06MB
wp_woocommerce_tax_rate_locations: Data: 0.02MB + Index: 0.03MB
wp_woocommerce_shipping_zones: Data: 0.02MB + Index: 0.00MB
wp_woocommerce_shipping_zone_locations: Data: 0.02MB + Index: 0.03MB
wp_woocommerce_shipping_zone_methods: Data: 0.02MB + Index: 0.00MB
wp_woocommerce_payment_tokens: Data: 0.02MB + Index: 0.02MB
wp_woocommerce_payment_tokenmeta: Data: 0.02MB + Index: 0.03MB
wp_woocommerce_log: Data: 0.02MB + Index: 0.02MB
wp_commentmeta: Data: 0.02MB + Index: 0.03MB
wp_comments: Data: 0.02MB + Index: 0.09MB
wp_links: Data: 0.02MB + Index: 0.02MB
wp_options: Data: 0.20MB + Index: 0.02MB
wp_postmeta: Data: 0.39MB + Index: 0.30MB
wp_posts: Data: 0.09MB + Index: 0.06MB
wp_tbc_email_log: Data: 0.13MB + Index: 0.00MB
wp_tbc_form_founder_contact_form: Data: 0.02MB + Index: 0.00MB
wp_tbc_form_mfts_contact_form: Data: 0.02MB + Index: 0.00MB
wp_tbc_form_mfts_monthly_donate_form: Data: 0.02MB + Index: 0.00MB
wp_tbc_form_mfts_praise_form: Data: 0.02MB + Index: 0.00MB
wp_tbc_form_mfts_signup_form: Data: 0.02MB + Index: 0.00MB
wp_termmeta: Data: 0.02MB + Index: 0.03MB
wp_terms: Data: 0.02MB + Index: 0.03MB
wp_term_relationships: Data: 0.02MB + Index: 0.02MB
wp_term_taxonomy: Data: 0.02MB + Index: 0.03MB
wp_usermeta: Data: 0.02MB + Index: 0.03MB
wp_users: Data: 0.02MB + Index: 0.05MB

Post Type Counts

attachment: 36
board: 40
musicians: 16
nav_menu_item: 10
news: 28
page: 17
partners: 4
post: 1
product: 21
product_variation: 10
revision: 26
shop_order: 2

Security

Secure connection (HTTPS): ❌Your store is not using HTTPS. Learn more about HTTPS and SSL Certificates.
Hide errors from visitors: ✔

Active Plugins (8)

Potent Donations for WooCommerce: by Potent Plugins – 1.1.2 – Not tested with the active version of WooCommerce
Duplicate Post: by Enrico Battocchi – 3.2.1
Jetpack by WordPress.com: by Automattic – 5.5.1
TBC Framework: by Thinkbox Creative – 4.02
Search Everything: by Sovrn
zemanta – 8.1.9

WooCommerce Stripe Gateway: by WooCommerce – 3.2.3 – Not tested with the active version of WooCommerce
WooCommerce Services: by Automattic – 1.9.0 – Not tested with the active version of WooCommerce
WooCommerce: by Automattic – 3.2.5 – 3.2.6 is available

Settings

API Enabled: ✔
Force SSL: –
Currency: USD ($)
Currency Position: left
Thousand Separator: ,
Decimal Separator: .
Number of Decimals: 2
Taxonomies: Product Types: donation (donation)
external (external)
grouped (grouped)
simple (simple)
variable (variable)

Taxonomies: Product Visibility: exclude-from-catalog (exclude-from-catalog)
exclude-from-search (exclude-from-search)
featured (featured)
outofstock (outofstock)
rated-1 (rated-1)
rated-2 (rated-2)
rated-3 (rated-3)
rated-4 (rated-4)
rated-5 (rated-5)

WC Pages

Shop base: #32 - /shop/
Cart: #33 - /cart/
Checkout: #34 - /checkout/
My account: #35 - /my-account/
Terms and conditions: ❌ Page not set

Theme

Name:
Version: – 0 is available
Author URL:
Child Theme: ❌ – If you are modifying WooCommerce on a parent theme that you did not build personally we recommend using a child theme. See: How to create a child theme
WooCommerce Support: ✔

Templates

Overrides: music-fts-theme/.DS_Store
music-fts-theme/woocommerce/archive-product.php
music-fts-theme/woocommerce/auth/footer.php
music-fts-theme/woocommerce/auth/form-grant-access.php
music-fts-theme/woocommerce/auth/form-login.php
music-fts-theme/woocommerce/auth/header.php
music-fts-theme/woocommerce/cart/cart-empty.php
music-fts-theme/woocommerce/cart/cart-item-data.php
music-fts-theme/woocommerce/cart/cart-shipping.php
music-fts-theme/woocommerce/cart/cart-totals.php
music-fts-theme/woocommerce/cart/cart.php
music-fts-theme/woocommerce/cart/cross-sells.php
music-fts-theme/woocommerce/cart/mini-cart.php
music-fts-theme/woocommerce/cart/proceed-to-checkout-button.php
music-fts-theme/woocommerce/cart/shipping-calculator.php
music-fts-theme/woocommerce/checkout/cart-errors.php
music-fts-theme/woocommerce/checkout/form-billing.php
music-fts-theme/woocommerce/checkout/form-checkout.php
music-fts-theme/woocommerce/checkout/form-coupon.php
music-fts-theme/woocommerce/checkout/form-login.php
music-fts-theme/woocommerce/checkout/form-pay.php
music-fts-theme/woocommerce/checkout/form-shipping.php
music-fts-theme/woocommerce/checkout/order-receipt.php
music-fts-theme/woocommerce/checkout/payment-method.php
music-fts-theme/woocommerce/checkout/payment.php
music-fts-theme/woocommerce/checkout/review-order.php
music-fts-theme/woocommerce/checkout/terms.php
music-fts-theme/woocommerce/checkout/thankyou.php
music-fts-theme/woocommerce/content-product.php
music-fts-theme/woocommerce/content-product_cat.php
music-fts-theme/woocommerce/content-single-product.php
music-fts-theme/woocommerce/content-widget-product.php
music-fts-theme/woocommerce/emails/admin-cancelled-order.php
music-fts-theme/woocommerce/emails/admin-failed-order.php
music-fts-theme/woocommerce/emails/admin-new-order.php
music-fts-theme/woocommerce/emails/customer-completed-order.php
music-fts-theme/woocommerce/emails/customer-invoice.php
music-fts-theme/woocommerce/emails/customer-new-account.php
music-fts-theme/woocommerce/emails/customer-note.php
music-fts-theme/woocommerce/emails/customer-on-hold-order.php
music-fts-theme/woocommerce/emails/customer-processing-order.php
music-fts-theme/woocommerce/emails/customer-refunded-order.php
music-fts-theme/woocommerce/emails/customer-reset-password.php
music-fts-theme/woocommerce/emails/email-addresses.php
music-fts-theme/woocommerce/emails/email-customer-details.php
music-fts-theme/woocommerce/emails/email-downloads.php
music-fts-theme/woocommerce/emails/email-footer.php
music-fts-theme/woocommerce/emails/email-header.php
music-fts-theme/woocommerce/emails/email-order-details.php
music-fts-theme/woocommerce/emails/email-order-items.php
music-fts-theme/woocommerce/emails/email-styles.php
music-fts-theme/woocommerce/emails/plain/admin-cancelled-order.php
music-fts-theme/woocommerce/emails/plain/admin-failed-order.php
music-fts-theme/woocommerce/emails/plain/admin-new-order.php
music-fts-theme/woocommerce/emails/plain/customer-completed-order.php
music-fts-theme/woocommerce/emails/plain/customer-invoice.php
music-fts-theme/woocommerce/emails/plain/customer-new-account.php
music-fts-theme/woocommerce/emails/plain/customer-note.php
music-fts-theme/woocommerce/emails/plain/customer-on-hold-order.php
music-fts-theme/woocommerce/emails/plain/customer-processing-order.php
music-fts-theme/woocommerce/emails/plain/customer-refunded-order.php
music-fts-theme/woocommerce/emails/plain/customer-reset-password.php
music-fts-theme/woocommerce/emails/plain/email-addresses.php
music-fts-theme/woocommerce/emails/plain/email-customer-details.php
music-fts-theme/woocommerce/emails/plain/email-downloads.php
music-fts-theme/woocommerce/emails/plain/email-order-details.php
music-fts-theme/woocommerce/emails/plain/email-order-items.php
music-fts-theme/woocommerce/global/breadcrumb.php
music-fts-theme/woocommerce/global/form-login.php
music-fts-theme/woocommerce/global/quantity-input.php
music-fts-theme/woocommerce/global/sidebar.php
music-fts-theme/woocommerce/global/wrapper-end.php
music-fts-theme/woocommerce/global/wrapper-start.php
music-fts-theme/woocommerce/loop/add-to-cart.php
music-fts-theme/woocommerce/loop/loop-end.php
music-fts-theme/woocommerce/loop/loop-start.php
music-fts-theme/woocommerce/loop/no-products-found.php
music-fts-theme/woocommerce/loop/orderby.php
music-fts-theme/woocommerce/loop/pagination.php
music-fts-theme/woocommerce/loop/price.php
music-fts-theme/woocommerce/loop/rating.php
music-fts-theme/woocommerce/loop/result-count.php
music-fts-theme/woocommerce/loop/sale-flash.php
music-fts-theme/woocommerce/myaccount/dashboard.php
music-fts-theme/woocommerce/myaccount/downloads.php
music-fts-theme/woocommerce/myaccount/form-add-payment-method.php
music-fts-theme/woocommerce/myaccount/form-edit-account.php
music-fts-theme/woocommerce/myaccount/form-edit-address.php
music-fts-theme/woocommerce/myaccount/form-login.php
music-fts-theme/woocommerce/myaccount/form-lost-password.php
music-fts-theme/woocommerce/myaccount/form-reset-password.php
music-fts-theme/woocommerce/myaccount/lost-password-confirmation.php
music-fts-theme/woocommerce/myaccount/my-account.php
music-fts-theme/woocommerce/myaccount/my-address.php
music-fts-theme/woocommerce/myaccount/my-downloads.php
music-fts-theme/woocommerce/myaccount/my-orders.php
music-fts-theme/woocommerce/myaccount/navigation.php
music-fts-theme/woocommerce/myaccount/orders.php
music-fts-theme/woocommerce/myaccount/payment-methods.php
music-fts-theme/woocommerce/myaccount/view-order.php
music-fts-theme/woocommerce/notices/error.php
music-fts-theme/woocommerce/notices/notice.php
music-fts-theme/woocommerce/notices/success.php
music-fts-theme/woocommerce/order/form-tracking.php
music-fts-theme/woocommerce/order/order-again.php
music-fts-theme/woocommerce/order/order-details-customer.php
music-fts-theme/woocommerce/order/order-details-item.php
music-fts-theme/woocommerce/order/order-details.php
music-fts-theme/woocommerce/order/order-downloads.php
music-fts-theme/woocommerce/order/tracking.php
music-fts-theme/woocommerce/product-searchform.php
music-fts-theme/woocommerce/single-product/add-to-cart/external.php
music-fts-theme/woocommerce/single-product/add-to-cart/grouped.php
music-fts-theme/woocommerce/single-product/add-to-cart/simple.php
music-fts-theme/woocommerce/single-product/add-to-cart/variable.php
music-fts-theme/woocommerce/single-product/add-to-cart/variation-add-to-cart-button.php
music-fts-theme/woocommerce/single-product/add-to-cart/variation.php
music-fts-theme/woocommerce/single-product/meta.php
music-fts-theme/woocommerce/single-product/photoswipe.php
music-fts-theme/woocommerce/single-product/price.php
music-fts-theme/woocommerce/single-product/product-attributes.php
music-fts-theme/woocommerce/single-product/product-image.php
music-fts-theme/woocommerce/single-product/product-thumbnails.php
music-fts-theme/woocommerce/single-product/rating.php
music-fts-theme/woocommerce/single-product/related.php
music-fts-theme/woocommerce/single-product/review-meta.php
music-fts-theme/woocommerce/single-product/review-rating.php
music-fts-theme/woocommerce/single-product/review.php
music-fts-theme/woocommerce/single-product/sale-flash.php
music-fts-theme/woocommerce/single-product/share.php
music-fts-theme/woocommerce/single-product/short-description.php
music-fts-theme/woocommerce/single-product/stock.php
music-fts-theme/woocommerce/single-product/tabs/additional-information.php
music-fts-theme/woocommerce/single-product/tabs/description.php
music-fts-theme/woocommerce/single-product/tabs/tabs.php
music-fts-theme/woocommerce/single-product/title.php
music-fts-theme/woocommerce/single-product/up-sells.php
music-fts-theme/woocommerce/single-product-reviews.php
music-fts-theme/single-product.php version - is out of date. The core version is 1.6.4
music-fts-theme/woocommerce/taxonomy-product_cat.php
music-fts-theme/woocommerce/taxonomy-product_tag.php

Outdated Templates: ❌Learn how to update
`

</details>

[mikejolley]

This doesn't appear to be a problem in master/3.3. It only adds a new line item. Existing are left alone.

Testing with the dummy data.