• by Gavin O'Malley  @mp_gavin, June 11, 2015

Continuing to test ecommerce, Facebook is inviting more retailers to sell their wares right in users’ News Feeds and on their respective brand Pages.

In partnership with retail software company Shopify, Facebook is giving select U.S. merchants the chance to try out a “Buy” button.

A small group of Shopify merchants were already posting products with the call-to-action buttons, but Facebook has now agreed to expand the beta test to include a variety of businesses.

After adding the Facebook sales channel to their Shopify accounts, the Canadian company will help brands post products with buy buttons, promote those posts with paid advertising and manage the resulting customers and orders.

“Everything [merchants] need to manage [their] Facebook sales is provided by Shopify,” Satish Kanwar, director of product at Shopify, writes on a new blog post.

For Facebook, the buy-button expansion is just the latest effort to explore ecommerce. Earlier this year, it unveiled Product Ads -- a format for brands to show off multiple offerings, and in some cases, their entire inventory.

In tests, brands appear to be pleased with Product Ads. Earlier this year, Kristi Argyilan, senior vice president at Target, reported that the ads resulted in a 20% increase in conversion compared to other Facebook ads.

Facebook is not the only social leader testing ecommerce. In partnership with Shopify and some top retailers, Pinterest just debuted buyable Pins online and on mobile devices. Shortly, when users spot a Pin with a blue price, which means they can buy the featured product on Pinterest.

With the service, Pinterest doesn't plan on taking a cut of retailers’ transactions. “Buyable Pins are free to merchants and Pinners,” a company spokesman recently told Social Media & Marketing Daily.

Twitter began testing a buy button in tweets, last year. More recently, it has been inviting advertisers to create credit-card-connected promotions, and share them with users directly in their timelines.

Despite its promise, however, social media has yet to carve out a significant share of the ecommerce market. In fact, social media channels -- including Facebook, Twitter, Instagram, and Pinterest -- contributed just 1.7% of total e-commerce sales, last year, research firm Custora recently reported.