Site Migration: Add A/B test check before showing certain UI/UX updates

[sixhours]

Proposed Changes

• We have a variation of the new migration flow working behind a feature flag migration-flow/experiment.
• This swaps out the changes behind the feature flag for an upcoming A/B test assignment -- users assigned to the treatment group will see the UI/UX changes.

Why are these changes being made?

• p9Jlb4-fiH-p2 A/B testing these changes

Testing Instructions

• TBD until the test has been set up in ExPlat

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
  • For UI changes, have we tested the change in various languages (for example, ES, PT, FR, or DE)? The length of text and words vary significantly between languages.
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-128189

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-128189&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-128189&env=a8c-for-agencies

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

App Entrypoints (~1739 bytes removed 📉 [gzipped])

name                   parsed_size           gzip_size
entry-stepper              -2133 B  (-0.1%)     -383 B  (-0.1%)
entry-main                  -758 B  (-0.0%)    -1530 B  (-0.3%)
entry-login                 -758 B  (-0.0%)    -1543 B  (-0.3%)
entry-subscriptions         -729 B  (-0.0%)     -214 B  (-0.0%)
entry-domains-landing       -729 B  (-0.1%)     -214 B  (-0.1%)
entry-browsehappy           -729 B  (-0.3%)     -214 B  (-0.3%)

Common code that is always downloaded and parsed every time the app is loaded, no matter which route is used.

Sections (~3356 bytes removed 📉 [gzipped])

name                                parsed_size           gzip_size
update-design-flow                       -962 B  (-0.1%)     -667 B  (-0.2%)
design-first-flow                        -896 B  (-2.2%)      -64 B  (-0.7%)
onboarding-flow                          -858 B  (-0.9%)     -109 B  (-0.9%)
with-theme-assembler-flow                -766 B  (-0.4%)     -100 B  (-0.2%)
update-options-flow                      -766 B  (-1.0%)     -100 B  (-1.5%)
trial-wooexpress-flow                    -766 B  (-1.0%)      -94 B  (-1.2%)
tailored-ecommerce-flow                  -766 B  (-0.9%)      -99 B  (-1.2%)
site-setup-wg                            -766 B  (-0.5%)     -107 B  (-0.3%)
site-setup-flow                          -766 B  (-0.5%)     -107 B  (-0.3%)
site-migration-flow                      -766 B  (-0.6%)     -104 B  (-0.5%)
readymade-template-flow                  -766 B  (-0.3%)      -96 B  (-0.1%)
migration-signup                         -766 B  (-0.9%)     -103 B  (-0.9%)
migration-flow                           -766 B  (-0.7%)     -104 B  (-0.6%)
import-flow                              -766 B  (-0.8%)     -100 B  (-0.7%)
hosted-site-migration-flow               -766 B  (-0.6%)     -104 B  (-0.5%)
free-post-setup-flow                     -766 B  (-1.0%)      -98 B  (-1.5%)
entrepreneur-flow                        -766 B  (-0.3%)      -98 B  (-0.1%)
assembler-first-flow                     -766 B  (-0.3%)      -97 B  (-0.2%)
ai-assembler-flow                        -766 B  (-0.6%)     -103 B  (-0.5%)
hundred-year-plan                        -740 B  (-1.5%)      -42 B  (-0.3%)
start-writing-flow                       -696 B  (-1.8%)      -57 B  (-0.6%)
newsletter-flow                          -481 B  (-1.4%)      -87 B  (-1.0%)
newsletter-post-setup-flow               +337 B  (+0.1%)      +62 B  (+0.1%)
link-in-bio-post-setup-flow              +337 B  (+0.1%)      +62 B  (+0.1%)
write-flow                               -289 B  (-0.0%)    -1564 B  (-0.5%)
build-flow                               -289 B  (-0.0%)    -1568 B  (-0.5%)
link-in-bio-tld-flow                     -251 B  (-0.0%)    -2327 B  (-0.4%)
stepper-user-step                        -196 B  (-0.1%)     +445 B  (+0.6%)
copy-site-flow                           -196 B  (-0.0%)     -689 B  (-0.2%)
reblogging-flow                          -173 B  (-2.3%)      -31 B  (-1.6%)
new-hosted-site-flow                     -173 B  (-1.5%)      -34 B  (-1.2%)
hundred-year-domain                      -108 B  (-0.2%)      -29 B  (-0.2%)
new-hosted-site-flow-user-included        -65 B  (-0.9%)       -7 B  (-0.3%)
connect-domain                            -65 B  (-0.2%)       -7 B  (-0.1%)

Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Async-loaded Components (~820 bytes removed 📉 [gzipped])

name                                        parsed_size           gzip_size
async-load-calypso-my-sites-checkout-modal       -196 B  (-0.0%)     -775 B  (-0.2%)
async-load-signup-steps-design-picker            -108 B  (-0.1%)      -45 B  (-0.2%)

React components that are loaded lazily, when a certain part of UI is displayed for the first time.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• notifications
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug add/ab-test-migration-experiment on your sandbox.