Create mocks for the entire checkout extension API by kumar303 · Pull Request #3902 · Shopify/ui-extensions

kumar303 · 2026-02-12T14:21:43Z

Follow up to #3899 that adds a complete, type-safe mock of the checkout extension API

👁️ How to review this PR

📖 Read the main developer-facing documentation
📖 Read the Checkout specific documentation
Try running tests in the example app on this branch

kumar303 · 2026-02-12T14:21:59Z

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packages/ui-extensions-tester/src/checkout/factories.ts

jamesvidler

This is really great work! I'd like to see us add some type safety for the targets so we don't get into scenarios where we forget to update the mocks as targets change.

packages/ui-extensions-tester/src/checkout/factories.ts

jamesvidler · 2026-03-10T14:29:41Z

examples/testing/checkout-basic-testing-example/package.json

@@ -0,0 +1,29 @@
+{
+  "name": "checkout-basic-testing-example",
+  "version": "1.0.0",


I had to add

"type": "module",

Otherwise I got:

Error [ERR_REQUIRE_ESM]: require() of ES Module /Users/jkv/src/github.com/Shopify/ui-extensions/examples/testing/checkout-basic-testing-example/node_modules/vite/dist/node/index.js from /Users/jkv/src/github.com/Shopify/ui-extensions/examples/testing/checkout-basic-testing-example/node_modules/vitest/dist/config.cjs not supported. Instead change the require of index.js in /Users/jkv/src/github.com/Shopify/ui-extensions/examples/testing/checkout-basic-testing-example/node_modules/vitest/dist/config.cjs to a dynamic import() which is available in all CommonJS modules. at _require.extensions.<computed> [as .js] (file:///Users/jkv/src/github.com/Shopify/ui-extensions/examples/testing/checkout-basic-testing-example/node_modules/vite/dist/node/chunks/config.js:35920:9) at Object.<anonymous> (/Users/jkv/src/github.com/Shopify/ui-extensions/examples/testing/checkout-basic-testing-example/node_modules/vitest/dist/config.cjs:5:12) at _require.extensions.<computed> [as .js] (file:///Users/jkv/src/github.com/Shopify/ui-extensions/examples/testing/checkout-basic-testing-example/node_modules/vite/dist/node/chunks/config.js:35920:9) { code: 'ERR_REQUIRE_ESM' }

When running the tests in here.

Huh. So weird.

jamesvidler · 2026-03-10T14:33:03Z

packages/ui-extensions-tester/src/checkout/factories.ts

+const checkoutMockFactories: Partial<CheckoutMockFactory> = {
+  // CheckoutApi & StandardApi
+  'purchase.checkout.actions.render-before': createCheckoutStandardMock,
+  'Checkout::Actions::RenderBefore': createCheckoutStandardMock,


Do you think we need to support the legacy targets here? I thought we removed these types from the library in latest versions?

Ah, these snuck in. The types weren't removed from the library because it was too hard to support removal in checkout-web when I tried. Maybe we should ask River to try it again :thinking_face:

I'll need to leave them in for now since the typing is exhaustive.

packages/ui-extensions-tester/src/checkout/factories.ts

jamesvidler · 2026-03-10T14:35:31Z

packages/ui-extensions-tester/src/checkout/README.md

+extension.shopify.lines.value = [
+  createCartLine({quantity: 2}),
+  createCartLine({
+    id: 'gid://shopify/CartLine/2',
+    merchandise: {
+      type: 'variant',
+      id: 'gid://shopify/ProductVariant/99',
+      title: 'Large Widget',
+      selectedOptions: [],
+      product: {
+        id: 'gid://shopify/Product/42',
+        vendor: 'Acme',
+        productType: 'widget',
+      },
+      requiresShipping: true,
+    },
+  }),
+];


Would this also set the .current internally that we expose for backwards compatibility? Or, do we still expose that - I haven't used remote-dom too much lately.

No we don't document that. We should have just removed it entirely. That was probably a mistake. We don't need to support it in the mocks.

kumar303 mentioned this pull request Feb 12, 2026

Add a testing library for ui-extensions #3899

Open

kumar303 force-pushed the 02-12-create_mocks_for_the_entire_checkout_extension_api branch from 5c62f76 to d914c44 Compare February 12, 2026 14:41

kumar303 mentioned this pull request Feb 12, 2026

Create mocks for the entire point-of-sale extension API #3904

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kumar303 force-pushed the 02-12-create_mocks_for_the_entire_checkout_extension_api branch 3 times, most recently from 247ecdf to 844aff7 Compare February 12, 2026 17:23

kumar303 mentioned this pull request Feb 12, 2026

Create mocks for the entire Customer Account extension API #3905

Open

kumar303 force-pushed the 02-12-create_mocks_for_the_entire_checkout_extension_api branch from 844aff7 to c8b1e1c Compare February 12, 2026 19:44

kumar303 mentioned this pull request Feb 12, 2026

Create mocks for the entire Admin extension API #3914

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kumar303 marked this pull request as ready for review February 24, 2026 14:27

kumar303 requested review from igor10k and jamesvidler February 24, 2026 14:28

cpeddecord reviewed Feb 24, 2026

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jamesvidler reviewed Mar 10, 2026

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Create mocks for the entire checkout extension API

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Create mocks for the entire checkout extension API#3902

Create mocks for the entire checkout extension API#3902
kumar303 wants to merge 1 commit into02-11-create_a_testing_library_for_ui-extensions_proof_of_concept_from
02-12-create_mocks_for_the_entire_checkout_extension_api

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