Bd Companion Plugin

better-data: Companion plugin testbed

For library maintainers working in the integration testbed at wp-content/plugins/better-data-plugin-test/. The plugin's job is to verify better-data behavior against real WordPress — things that pure unit tests can't reach (cache primings, metadata_exists semantics, wp_slash round-trips, REST schema actually appearing in WP_REST_Server, locale switching, encryption key constants).

Misconception this skill corrects

> "I'll add the new feature's integration test directly inside better-data/tests/Unit/ so everything's in one place."

Wrong. tests/Unit/ is the WP-free zone — every test there must run with composer test against a clean PHP environment, no WP bootstrap, no MySQL. That's intentional: contributors can run the unit suite in seconds. WP-aware behavior goes in the companion plugin, where there's a real WordPress to talk to.

The split:

| Concern | Lives in | |---|---| | Pure type coercion, attribute reflection, builder logic | better-data/tests/Unit/ | | wp_slash round-trip, metadata_exists semantics, REST registration | better-data-plugin-test/src/Smoke/ | | Multi-step scenarios (encrypt → store → fetch → decrypt → reveal), edge-case discovery | better-data-plugin-test/src/Stress/ | | Visual confirmation (admin page renders print_r($dto)) | better-data-plugin-test/src/Admin/ |

Other AI-prone misconceptions:

• "I'll let the plugin depend on WooCommerce since it makes the Order fixture realistic." Wrong — the plugin must run on a clean WP install with NOTHING but better-data. WC, ACF, custom-fields plugins are out. The Widget Shop fixture (bd_widget CPT + bd_order CPT + ShopSettingsDto) IS the realistic consumer because it's self-contained.
• "If a stress scenario is flaky, I'll mark it as NOTE instead of fixing it." Wrong — NOTE is for documented quirks the library legitimately surfaces (e.g. "WP serializes integer-keyed arrays as objects in some contexts"). A flaky test is a FAIL waiting to happen; fix it.
• "I'll move the new behavior into the library after the plugin verifies it." Wrong direction — integration-only behavior STAYS in the plugin. The library stays shape-agnostic.

When to use this skill

Trigger when ANY of the following is true:

• The diff modifies any file under wp-content/plugins/better-data-plugin-test/.
• Adding a new smoke or stress scenario.
• Adding a new CLI subcommand under bin/wp better-data .
• Adding a new admin page, fixture DTO, or seed/purge routine.
• Reviewing a PR that adds WordPress / WC / ACF as a Composer dep on the plugin.

Workflow

1. Three test tiers — pick the right one

Smoke — regression coverage.

src/Smoke/
├── Runner.php              ← scenario list + dispatcher
└── Assertion.php           ← per-scenario assertions

Smoke scenarios run on every library change. They're short, focused, fast. A FAIL here means a regression — never ship over it. Add a smoke scenario for any new public behavior.

Stress — deep integration.

src/Stress/
├── Runner.php              ← scenario list + dispatcher
└── Finding.php             ← OK / FAIL / NOTE findings

Stress scenarios are longer-running, multi-step, edge-case-hunting. They produce three outcomes:

| Verdict | Meaning | |---|---| | OK | Library behaves as expected for this scenario | | FAIL | Bug — blocks the change | | NOTE | Discovery — library surfaces a quirk worth documenting (e.g. "PHP arrays with integer keys round-trip as JSON objects in this context") |

NOTE is the unique value-add: it lets a stress run discover and SURFACE library limits without failing.

Admin pages — visual confirmation.

src/Admin/
├── AdminPage.php           ← base
├── ShopSettingsPage.php    ← renders print_r($dto) post-hydration
├── …

Admin pages are eyeball-level proof. Use for:

• Visually confirming Secret renders as '***'.
• Confirming locale-switched email subject lines render in the right language.
• Manually playing with Presenter chains.

Not test scaffolding — they're for human verification.

2. The Widget Shop fixture is the canonical consumer

The plugin defines:

• bd_widget CPT — products in the fictional shop.
• bd_order CPT — orders.
• ShopSettingsDto — store-level settings (currency, tax, encrypted Stripe key).
• WidgetDto, LineItemDto, OrderDto, CustomerDto, AddressDto — see [src/Dto/](src/Dto/).

When you add a new feature:

1. Can it fit into the Widget Shop? (Yes for most things — sinks, sources, validation rules, presenter methods.) Extend the existing fixtures.
2. Does it genuinely need a new fixture? (E.g. testing a new SOURCE that doesn't fit the shop concept.) Add a fixture, but keep the dependency-tree minimal.

Adding a new CPT just for one test is over-fitting. Adding a new DTO that consumes existing CPTs is fine.

3. CLI subcommands

The plugin's main driving surface is CLI:

wp better-data smoke      # run all smoke scenarios
wp better-data stress     # run all stress scenarios
wp better-data seed       # populate the Widget Shop with sample data
wp better-data purge      # clear all bd_* posts and meta
wp better-data inventory  # list every DTO + scenario the plugin exposes

Existing files: [src/Cli.php](src/Cli.php), [src/StressCli.php](src/StressCli.php), [src/SeedCli.php](src/SeedCli.php), [src/PurgeCli.php](src/PurgeCli.php), [src/InventoryCli.php](src/InventoryCli.php).

Add a new subcommand when you have a coherent chunk of work that doesn't fit the existing five (e.g. bench for benchmark scenarios). Don't add one for a single scenario — that goes inside an existing tier.

4. Adding a stress scenario

// src/Stress/EncryptionRotationScenario.php
namespace BetterDataPluginTest\Stress;

final class EncryptionRotationScenario
{
    public function run(): array  // list
    {
        $findings = [];

        // 1. Set up: define BETTER_DATA_ENCRYPTION_KEY, encrypt + store a Secret.
        // 2. Define BETTER_DATA_ENCRYPTION_KEY_PREVIOUS = old key.
        // 3. Read back: should still decrypt under previous key.
        // 4. Re-write: should encrypt under new key.
        // 5. Read back: under new key.
        // 6. Verify the wp_options row's stored value uses the new key envelope.

        $findings[] = Finding::ok('round-trip under rotation works');
        $findings[] = Finding::note('previous-key rows are not auto-rewritten on read; lazy migration on write only');

        return $findings;
    }
}

Wire it into the runner:

// src/Stress/Runner.php
public function scenarios(): array
{
    return [
        new RoundTripScenario(),
        // ...
        new EncryptionRotationScenario(),
    ];
}

5. Adding a smoke scenario

Smoke is more compact — assertion-style, no Finding objects:

// src/Smoke/Runner.php — inside the scenario list:
$assertions->ok(
    'PostDto round-trips through PostSink + PostSource',
    fn () => $this->postRoundTrip(),
);

The assertion closure throws on failure or returns nothing on pass. Single-line scenario titles, single-step assertions.

6. Don't depend on WC / ACF / external plugins

The companion plugin's composer.json lists ONLY:

• php: ^8.3
• lonsdale201/better-data (path repository pointing back to ../../libraries/better-data)

No WooCommerce, no ACF, no Composer packages outside the library. Reason: a contributor cloning the library + plugin should be able to run the smoke + stress suite on a clean WP install, no setup choreography. If the plugin grew a dep on WC, half the contributors couldn't reproduce.

7. Run order

# In the library:
vendor/bin/phpunit               # unit suite — must be green first
vendor/bin/phpstan analyse       # static analysis
vendor/bin/php-cs-fixer fix      # style

# In the plugin (against a real WP):
wp better-data purge             # clean slate
wp better-data seed              # populate the Widget Shop
wp better-data smoke             # regression
wp better-data stress            # deep integration

# Iterate on FAIL findings until clean.

A successful sequence is the ship-readiness check. Library unit + static + style green, plugin smoke 100% pass, stress 0 FAIL.

Critical rules

• Plugin is internal — break its internals as needed. Not part of the library's public API; redesign freely to demonstrate a point.
• Three test tiers, pick the right one. Smoke = regression (never FAIL); Stress = integration (FAIL blocks, NOTE documents); Admin pages = visual confirmation.
• NOTE is for documented quirks, not flaky tests. A test that flakes is a FAIL waiting to happen — fix it.
• Widget Shop is the canonical fixture. Extend it; add new fixtures only when the new use case doesn't fit.
• No deps beyond better-data itself. Plugin must run on a clean WP install. No WC, no ACF, no third-party Composer packages.
• CLI is the driving surface. wp better-data {test, stress, seed, purge, inventory} covers the workflow; add a subcommand only for genuinely new categories.
• Integration-only behavior STAYS in the plugin. Don't promote a stress-only feature into the library.
• Smoke green + 0 FAIL stress = ship-ready. That's the gate.

Common mistakes

// WRONG — depending on WooCommerce in the plugin
// composer.json: "require": { "woocommerce/woocommerce-stubs": "^8.0" }
// Now contributors need WC installed to run the suite.

// RIGHT — keep the dep tree to better-data + WP

// WRONG — scenario marked NOTE because it's flaky
$findings[] = Finding::note('Sometimes the cache primes too late and we read a stale value');
// 🔴 a flake is a FAIL waiting to happen.

// RIGHT — fix it (add explicit cache priming, or design the scenario to be deterministic)
$findings[] = Finding::ok('cache primes correctly when explicitly warmed');

// WRONG — new CPT for one test
\register_post_type('bd_email_log', [...]);  // just to test EmailLogSink
// Bloats the fixture surface for everyone.

// RIGHT — extend the Widget Shop
// EmailLogDto becomes part of the bd_order CPT meta, or the bd_widget reviews flow.

// WRONG — promoting a plugin-only behavior into the library
// "OrderTotals helper grew useful — moving it into better-data/src/Helpers/"
// Library stays shape-agnostic; helpers are a consumer concern.

// RIGHT — keep it in the plugin

// WRONG — skipping wp better-data purge before stress
// Stale seed data from a previous run skews scenarios.

// RIGHT
wp better-data purge
wp better-data seed
wp better-data stress

// WRONG — putting integration-test code in the library
// better-data/tests/Integration/EncryptionRoundTripTest.php (requires WP bootstrap)
// Breaks the WP-free unit suite contract.

// RIGHT
// better-data-plugin-test/src/Stress/EncryptionRoundTripScenario.php

Cross-references

• Run bd-data-object when adding a new fixture DTO under src/Dto/.
• Run bd-source-adapter + bd-sink when the scenario covers a new WP store integration — the plugin is where you verify cache primings work.
• Run bd-security for stress scenarios involving Secret / #[Encrypted] — the plugin is where leak probes against live WP run.

What this skill does NOT cover

• Plugin distribution / packaging. The companion is repo-internal; it's not published.
• WordPress bootstrapping for the unit suite. Library unit tests must run WP-free.
• Performance benchmarking with realistic scale (10k posts, 1M meta rows). Stress is correctness-focused; benchmarks would be a separate bench subcommand.
• Plugin-level i18n. Plugin uses simple English strings; libraries' i18n behavior is in the library's tests.
• Admin UI design / UX. Admin pages exist for visual confirmation, not to demonstrate good UI.
• Multi-site behavior. WP multisite is an edge case for some sinks/sources; covered case-by-case in stress, not as a tier.

References

• Plugin entry: [wp-content/plugins/better-data-plugin-test/better-data-plugin-test.php](better-data-plugin-test.php) — bootstrap, CPT registration, CLI hookup.
• Widget Shop fixtures: [wp-content/plugins/better-data-plugin-test/src/Dto/](src/Dto/) — WidgetDto, OrderDto, LineItemDto, CustomerDto, AddressDto, ShopSettingsDto, EncryptedCredentialsDto, OptionalBeforeRequiredTrapFixture.
• Smoke runner: [wp-content/plugins/better-data-plugin-test/src/Smoke/Runner.php](Runner.php) and [src/Smoke/Assertion.php](Assertion.php).
• Stress runner: [wp-content/plugins/better-data-plugin-test/src/Stress/Runner.php](Runner.php) and [src/Stress/Finding.php](Finding.php) — Finding::ok, Finding::fail, Finding::note factories.
• CLI: [wp-content/plugins/better-data-plugin-test/src/Cli.php](Cli.php), [src/StressCli.php](StressCli.php), [src/SeedCli.php](SeedCli.php), [src/PurgeCli.php](PurgeCli.php), [src/InventoryCli.php](InventoryCli.php).
• Admin pages: [wp-content/plugins/better-data-plugin-test/src/Admin/](src/Admin/) — AdminPage base + concrete pages.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Lonsdale201
• Source: Lonsdale201/wp-agent-skills
• License: MIT

Install and usage instructions live in the source repository linked above.