Test Kitchen

https://wikitech.wikimedia.org/wiki/Test_Kitchen
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### Run eventgate-devserver locally

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Local_development_setup

Commands to install dependencies and start the eventgate-devserver for manual development environments.

```bash
$ cd extensions/EventLogging/devserver
$ npm install --no-optional
$ npm run eventgate-devserver
```

--------------------------------

### Install TestKitchen Extension

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Local_development_setup

Clone the TestKitchen extension repository into the extensions folder of your MediaWiki installation.

```bash
git clone https://gerrit.wikimedia.org/r/mediawiki/extensions/TestKitchen

```

--------------------------------

### Example Schema with Multiple Fragments

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Analytics

Example demonstrating how to combine multiple schema fragments for an A/B test scenario.

```APIDOC
### Example 1

Suppose we're running an A/B test on a new default skin for anonymous users and we are interested in measuring session length and average number of visited _articles_ per session.

The schema would use the following fragments: core identifiers, page, UI, and A/B testing via:

```yaml
allOf:
    - $ref: /fragment/analytics/common/1.0.0#
    - $ref: /fragment/analytics/web_identifiers/1.0.0#
    - $ref: /fragment/analytics/mediawiki_page/1.0.0#
    - $ref: /fragment/analytics/ui/1.0.0#
    - $ref: /fragment/analytics/ab_testing/1.0.0#
```

And the following fields would need to be included in the one (1) event logged by the instrument on every page load:

```yaml
required:
    - client_dt
    - web_session_id
    - web_pageview_id
    - page_namespace
    - ui_screen
    - test_name
    - test_group
```
```

--------------------------------

### Example Application Log Output

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Troubleshooting

Sample output from application logs showing git unified diffs for configuration changes.

```text
...varnish diff:
---
+++
@@ -1,500 +1,500 @@
 {
   "fy2025-26-we3.1-image-browsing-ab-test": {
     "domains": {
...
     },
     "end": "2025-11-12T14:30:00Z",
-    "start": "2025-11-08T14:30:00Z"
+    "start": "2025-11-06T14:30:00Z"
   }
 }
2025-11-06 23:22:48,309 - INFO - fields: xlab-mw-module-loaded-v2
2025-11-06 23:22:48,309 - INFO - IRC sending: !log Test Kitchen edge-unique experiments (poll 1536) - adds: none; removes: none; fields: xlab-mw-module-loaded-v2 - xLab/MPIC/TK tips at https://w.wiki/FwuD
2025-11-06 23:31:01,481 - INFO - Service alive with checks so far: 1560
```

--------------------------------

### Install Fresh Tool for JavaScript Environment

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Maintainer_introduction

Installs the Fresh tool, which provides a Docker container with pre-installed developer tools like Node.js and headless browsers for the JavaScript library. Run this command in your terminal.

```bash
curl -fsS 'https://gerrit.wikimedia.org/g/fresh/+/23.08.1/bin/fresh-install?format=TEXT' | base64 --decode | python3
```

--------------------------------

### Start ClickThroughRateInstrument with Experiment Data

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Measuring_clickthrough_rates

Use this snippet to attach a ClickThroughRateInstrument to elements for experiment data collection. It requires the 'ext.wikimediaEvents.testKitchen' module and ensures the experiment is active before starting the instrument.

```javascript
const { ClickThroughRateInstrument } = require( 'ext.wikimediaEvents.testKitchen' );

mw.loader.using( 'ext.testKitchen' ).then( () => {
	const experiment = mw.testKitchen.getExperiment( 'event-participant-count' );

    if ( experiment.isAssignedGroup( 'control', 'show' ) ) {
        $( 'a.ext-campaignevents-events-list-link' ).each(
            ( index, element ) => ClickThroughRateInstrument.start(
                'a.ext-campaignevents-events-list-link:nth-of-type(' + ( index + 1 ) + ')',
                'Collaboration list event link',
                experiment
            )
        );
    }
} );

```

--------------------------------

### Update Instrument Start Date in Test Kitchen DB

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Local_development_setup

Use `docker compose exec` and `mariadb` to update the `utc_start_dt` for an instrument if validation prevents setting a start date before today.

```bash
$ docker compose exec test-kitchen-db bash
$ mariadb -umaria -pmaria
MariaDB [(none)]> update test_kitchen.instruments set utc_start_dt = '2026-03-11 14:30:00' where id=...;

```

--------------------------------

### Example Schema with Multiple Fragments

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Analytics/Fragments

An example demonstrating how to combine multiple schema fragments, including common, web identifiers, page, UI, and A/B testing, for a specific analytics use case.

```APIDOC
## Example 1

Suppose we're running an A/B test on a new default skin for anonymous users and we are interested in measuring session length and average number of visited _articles_ per session.

The schema would use the following fragments: core identifiers, page, UI, and A/B testing via:

```yaml
allOf:
    - $ref: /fragment/analytics/common/1.0.0#
    - $ref: /fragment/analytics/web_identifiers/1.0.0#
    - $ref: /fragment/analytics/mediawiki_page/1.0.0#
    - $ref: /fragment/analytics/ui/1.0.0#
    - $ref: /fragment/analytics/ab_testing/1.0.0#
```

And the following fields would need to be included in the one (1) event logged by the instrument on every page load:

```yaml
required:
    - client_dt
    - web_session_id
    - web_pageview_id
    - page_namespace
    - ui_screen
    - test_name
    - test_group
```
```

--------------------------------

### Limit metric to experiment cohort duration

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Automated_analysis_of_experiments

Example of using the start_date parameter to restrict a metric calculation to a specific time window relative to the experiment start.

```sql
TO_TIMESTAMP('{start_date}') + INTERVAL 72 HOUR
```

--------------------------------

### A/B Test Data Examples

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Analytics

Examples of the 'tests' array structure for A/B testing. The array can be empty, contain a single test, or multiple tests.

```json
"tests": []
```

```json
"tests": [ { "name": "growth-homepage", "group": "control" } ]
```

```json
"tests": [ { "name": "growth-homepage", "group": "variant-1" }, { "name": "growth-help-panel", "group": "variant-2" } ]
```

--------------------------------

### Start Click-Through Rate Instrument

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Measuring_clickthrough_rates

Initializes and starts a ClickThroughRateInstrument for tracking clicks on collaboration event links. Ensure the INSTRUMENT_NAME matches the Test Kitchen UI configuration.

```javascript
const { ClickThroughRateInstrument } = require( 'ext.wikimediaEvents.testKitchen' );

const INSTRUMENT_NAME = 'collaboration-list-event-links-ctr';
const instrument = mw.testKitchen.getInstrument( INSTRUMENT_NAME );

$( 'a.ext-campaignevents-events-list-link' ).each(
    ( index, element ) => ClickThroughRateInstrument.start(
        'a.ext-campaignevents-events-list-link:nth-of-type(' + (index + 1) + ')',
        'Collaboration list event link',
        instrument
    )
);

```

--------------------------------

### Launch NodeJS Environment with Fresh

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Maintainer_introduction

Launches the NodeJS environment provided by Fresh. After running this command, your bash prompt will change, indicating you are inside the container. You can then install dependencies using npm.

```bash
santi@mylaptop ~ % fresh-node
# 🌱 Fresh 23.08.1 ░ Node.js 18 ░ npm 9 ░ Firefox 102 ░ Chromium 115 ░ Debian 11 Bullseye
# image: docker-registry.wikimedia.org/releng/node18-test-browser:0.0.1
# mount: /santi      ➟ /Users/santi      (read-write)

nobody@e99bb96f8bd0:/santi$ npm install
. . .
. . .

```

--------------------------------

### Custom Stream Configuration - PHP

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Measure_product_health

Example configuration for a custom stream in PHP. This defines the schema and destination for events.

```php
'mediawiki_product_metrics_your_custom_stream_name' => [
    'schema_title' => 'analytics/product_metrics/web/translation',
    'destination_event_service' => 'eventgate-analytics-external',
    'producers' => [
        'eventgate' => [
            'enrich_fields_from_http_headers' => [
                'http.request_headers.user-agent' => false,
            ],
        ],
        'metrics_platform_client' => [
            'provide_values' => [
                'performer_is_logged_in',
                'performer_is_temp',
                'performer_pageview_id',
                'mediawiki_database',
            ],
        ],
    ],
],

```

--------------------------------

### Publish New Java Release

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Deploy_client_libraries

Commands to publish a new release of the Java client library to Maven Central. Requires proper credentials and GPG key setup.

```bash
./mvnw -f java -B -P deploy-central release:clean
```

```bash
./mvnw -f java -B -P deploy-central release:prepare
```

```bash
./mvnw -f java -B -P deploy-central release:perform
```

--------------------------------

### Custom Stream Configuration Example

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Create_an_instrument

Define a custom stream configuration, including schema title, destination, and producer-specific settings. This is used when the default stream and schema are insufficient.

```php
'mediawiki_product_metrics_your_custom_stream_name' => [
    'schema_title' => 'analytics/product_metrics/web/translation',
    'destination_event_service' => 'eventgate-analytics-external',
    'producers' => [
        'eventgate' => [
            'enrich_fields_from_http_headers' => [
                'http.request_headers.user-agent' => false,
            ],
        ],
        'test_kitchen_client' => [
            'provide_values' => [
                'performer_is_logged_in',
                'performer_is_temp',
                'performer_pageview_id',
                'mediawiki_database',
            ],
        ],
    ],
],

```

--------------------------------

### Custom Stream Configuration - MediaWiki Config

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Measure_product_health

Example of adding a custom stream name to the `$wgTestKitchenExperimentStreamNames` configuration variable in MediaWiki.

```php
'wgTestKitchenExperimentStreamNames' => [
	'default' => [
		'product_metrics.web_base',
		'mediawiki.product_metrics.reading_list',
		'mediawiki.product_metrics.readerexperiments_imagebrowsing',
		'mediawiki.product_metrics.your_custom_stream_name'

	],
],

```

--------------------------------

### Run PHP Development Environment with Docker

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Maintainer_introduction

Starts a bash session within the buster-php74 Docker image for PHP development. This is a temporary solution until a dedicated PHP environment is available. It mounts the current directory to /work for persistent changes.

```bash
docker run -it -v .:/work docker-registry.wikimedia.org/dev/buster-php74:1.1.0-s2 /bin/bash
cd /work
rm -r vendor
rm composer.lock

```

--------------------------------

### Log IRC Message from wmftkbot

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Troubleshooting

This is an example of a log message generated by the wmftkbot on Libera IRC, indicating changes to experiment configurations in Test Kitchen. It shows additions, removals, and modified fields for experiments.

```log
wmftkbot https://toolsadmin.wikimedia.org/tools/id/tk 
!log Test Kitchen edge-unique experiments (poll 4689) - adds: none; removes: none; fields: fy2025-26-we3.1-image-browsing-ab-test, hcaptcha-on-french-wikipedia, xlab-mw-module-loaded-v2 - xLab/MPIC/TK tips at https://w.wiki/FwuD
```

--------------------------------

### Troubleshoot Test Kitchen Deployment

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Test_Kitchen_UI/Administration

Connect to the deployment server, set the specific Kubernetes environment for the next deployment, and list events. This helps in identifying issues during the deployment process.

```bash
$ ssh deployment.eqiad.wmnet
$ kube-env test-kitchen-next-deploy dse-k8s-eqiad
$ kubectl get events
```

--------------------------------

### View Test Kitchen Logs

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Test_Kitchen_UI/Administration

Connect to the deployment server, set the Kubernetes environment, and stream pod logs. This is useful for monitoring application behavior and diagnosing runtime errors.

```bash
$ ssh deployment.eqiad.wmnet
$ kube_env <environment> dse-k8s-eqiad
$ kubectl get pods -w
$ kubectl logs -f <pod_name> -c <container_name> --tail=10
```

```json
{"level":50,"time":1714483575453,"pid":1,"hostname":"test-kitchen-staging-66554859c4-p9m28","msg":"Error while setting an env variable. There is no value for SAL_PASSWORD"}
{"level":30,"time":1714483575592,"pid":1,"hostname":"test-kitchen-staging-66554859c4-p9m28","msg":"Connected to the database at an-mariadb1001.eqiad.wmnet:test_kitchen_staging"}
{"level":30,"time":1714483575600,"pid":1,"hostname":"test-kitchen-staging-66554859c4-p9m28","msg":"test-kitchen has started listening on port 8080"}
```

--------------------------------

### Configure Local MediaWiki Event Streams

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Local_development_setup

Define the `product_metrics.web_base` stream and other custom streams in your MediaWiki's `LocalSetting.php` file to work with Test Kitchen.

```php
$wgEventStreams = [
    'product_metrics.web_base' => [
		'schema_title' => 'analytics/test_kitchen/web/base',
		'destination_event_service' => 'eventgate-analytics-external',
		'producers' => [
			'metrics_platform_client' => [],
		],
		'eventgate' => [
			'enrich_fields_from_http_headers' => [
				'http.request_headers.user-agent' => false,
			],
			'use_edge_uniques' => true,
		]
	],
];

```

--------------------------------

### Deploy Changes with Helmfile

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Test_Kitchen_UI/Administration

Use this command to deploy changes to the Test Kitchen environments after preparing and reviewing them. Ensure you are in the correct directory and have pulled the latest changes.

```bash
# Do the following once you have prepared the change and the change has been reviewed and merged
ssh deployment.eqiad.wmnet
cd /srv/deployment-charts
git log -n 1
# Check that the change has been pulled
cd helmfile.d/dse-k8s-services/<environment>
# Check changes and deploy
helmfile -e dse-k8s-eqiad diff
helmfile -e dse-k8s-eqiad -i apply
```

--------------------------------

### Configure TestKitchen Extension in LocalSettings.php

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Local_development_setup

Load the TestKitchen extension and configure its settings, including the service URL and enabling features like configuration fetching and experiments.

```php
// Load the extension

```

```php
wfLoadExtensions( [
    // other extensions might be here
    'TestKitchen',
] );

```

```php
// Set the Test Kitchen service URL (this example considers it's running on your localhost)

```

```php
// Linux users might need to use '127.17.0.1' instead of 'host.docker.internal'. The latter doesn't work for some distributions

```

```php
$wgTestKitchenInstrumentConfiguratorBaseUrl = 'http://host.docker.internal:8086';

```

```php
// Ensures, when testing/debugging with Test Kitchen UI and MediaWiki locally, Test Kitchen API is used

```

```php
$wgTestKitchenEnableConfigsFetching = true;

```

```php
// Enable experimentation capabilities (disabled by default)

```

```php
$wgTestKitchenEnableExperiments = true;

```

--------------------------------

### Allow-list Stream in InitialiseSettings.php

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Conduct_an_experiment

Add the stream name to the Test Kitchen experiment stream allow-list.

```php
'wgTestKitchenExperimentStreamNames' => [
    'default' => [
        // ...
        'mediawiki.product_metrics.translation_mint_for_readers.experiments',
    ],
],
```

--------------------------------

### Bad Use of action_context: Data Stuffing Example

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Decision_Records/Increase_action_context_limit

This example shows a poor use of action_context, where excessive and potentially unnecessary data is stuffed into the field, including page details, user interaction metrics, and system information.

```json
{
  "action": "click",
  "action_source": "get_support",
  "action_context": {
    "page_name": "Special:Preferences",
    "scroll_position": 342,
    "mouse_x": 1024,
    "mouse_y": 768,
    "time_on_page": 47,
    "previous_5_pages": [...],
    "browser_memory_usage": "245MB",
    "cpu_usage": "23%",
    "network_speed": "4G"
  }
}
```

--------------------------------

### Donation Event Data Structure

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Automated_analysis_of_experiments/Prepared_metrics

Example JSON schema for donation events used in product metrics.

```json
{
  "$schema": "/analytics/product_metrics/web/base/1.4.1",
  "meta": {
    "stream": "product_metrics_web_base"
  },
  "action": "donate",
  "action_subtype": "amount",
  "action_context": "123.45",
  "instrument_name": "Donation processor",
  "experiment": {
    "coordinator": "default",
    "enrolled": "{experiment_machine_name}",
    "assigned": "{group_machine_name}
  }
}
```

--------------------------------

### mw.testKitchen.getExperiment

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/SDK/JavaScript_SDK

Retrieves an instance of an existing experiment based on the configuration defined in the Test Kitchen UI.

```APIDOC
## mw.testKitchen.getExperiment

### Description
Get an instance of an existing Experiment according to the configuration defined in Test Kitchen UI.

### Parameters
#### Path Parameters
- **experimentName** (string) - Required - Name of the experiment
```

--------------------------------

### Fetch and verify client library with maintenance scripts

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Deploy_client_libraries

Use these commands to update and verify the EventLogging extension's foreign resources.

```bash
$ php maintenance/run.php ./maintenance/manageForeignResources.php --extension EventLogging update
$ php maintenance/run.php ./maintenance/manageForeignResources.php --extension EventLogging verify
... verifying 'metrics-platform'
```

--------------------------------

### Configure Docker Compose for Test Kitchen

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Local_development_setup

Add `test-kitchen` and `test-kitchen-db` services to your `docker-compose.override.yml` to enable the Test Kitchen UI and API for local development.

```yaml
services:
  eventlogging:
    build: "./extensions/EventLogging/devserver"
    volumes:
      - "./cache/events.json:/opt/eventlogging/events.json"
      - "./cache/eventgate.config.yaml:/opt/eventlogging/eventgate.config.yaml"
      - "./cache/primary:/opt/eventlogging/primary"
      - "./cache/secondary:/opt/eventlogging/secondary"
    ports:
      - "8192:8192"

  test-kitchen:
    extends:
      file: ./extensions/TestKitchen/devserver/docker-compose.yml
      service: test-kitchen

  test-kitchen-db:
    extends:
      file: ./extensions/TestKitchen/devserver/docker-compose.yml
      service: test-kitchen-db
    volumes:
      - ./cache/test-kitchen-db:/var/lib/mysql

```

--------------------------------

### Get Server-Side Experiment Object

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Conduct_an_experiment

Retrieve the experiment object server-side to access experiment details. Requires the ExperimentManager service.

```php
const EXPERIMENT_NAME = 'larger-default-font-size';
const TREATMENT_GROUP_NAME = 'x-large';

$experimentManager = MediaWikiServices::getInstance()->getService( 'TestKitchen.Sdk.ExperimentManager' );

$experiment = $experimentManager->getExperiment( EXPERIMENT_NAME );
```

--------------------------------

### Get Client-Side Experiment Object

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Conduct_an_experiment

Retrieve the experiment object client-side to access experiment details. This is used for client-side feature toggling and analytics.

```javascript
const EXPERIMENT_NAME = 'larger-default-font-size';
const TREATMENT_GROUP_NAME = 'x-large'; // only needed for feature toggling, not analytics

const experiment = mw.testKitchen.getExperiment( EXPERIMENT_NAME );
```

--------------------------------

### Good Use of action_context: Timed Ticks

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Decision_Records/Increase_action_context_limit

Example of using action_context for measuring session length with timed ticks. The context includes the time in seconds.

```json
{"action": "tick", "action_context": {"time_s":<INT>}}
```

--------------------------------

### Misconfigured EventStreamConfig for MinT Experiment

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Incident_reports/2025-09-17_MinT_for_Readers_AA_test_missing_subject_IDs

Example of an incorrect stream configuration where the EventGate settings were placed in the wrong stanza, preventing proper subject ID hoisting.

```php
// https://gerrit.wikimedia.org/g/operations/mediawiki-config/+/acad29faf2f945642ef0f45cf5a9569b41a10fba/wmf-config/ext-EventStreamConfig.php#2388
'mediawiki.product_metrics.translation_mint_for_readers.experiments' => [
	'schema_title' => 'analytics/product_metrics/web/translation',
	'destination_event_service' => 'eventgate-analytics-external',
	'producers' => [
		'eventgate' => [
			'enrich_fields_from_http_headers' => [
				'http.request_headers.user-agent' => false,
			],
		],
		'metrics_platform_client' => [
			'provide_values' => [
				'mediawiki_database',
				'mediawiki_skin',
				'mediawiki_site_content_language',
				'mediawiki_site_content_language_variant',
				'page_content_language',
				'agent_client_platform',
				'agent_client_platform_family',
				'performer_session_id',
				'performer_active_browsing_session_token',
				'performer_is_logged_in',
				'performer_is_temp',
				'performer_language',
				'performer_language_variant',
				'performer_pageview_id',
			],
		],
	],
	'eventgate' => [
		'enrich_fields_from_http_headers' => [
			// Don't collect the user agent
			'http.request_headers.user-agent' => false,
		],
		'use_edge_uniques' => true,
	],
],
```

--------------------------------

### Send Event with JS Test Kitchen SDK

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Local_development_setup

Instantiate an instrument using the `mw.testKitchen.getInstrument` method and send an event with `myInstrument.send()` within the `ext.testKitchen` module.

```javascript
mw.loader.using( 'ext.testKitchen' ).then( () => {
    const myInstrument = mw.testKitchen.getInstrument( 'my-experiment' );
    myInstrument.send( 'some_action' );
} );

```

--------------------------------

### Define a custom schema in YAML

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Custom_schemas

Example of a custom schema definition combining common, platform, and custom fragments. Replace x.x.x with the appropriate fragment versions.

```yaml
title: analytics/product_metrics/web/translation
description: Web schema for wiki tranlation workflows.
$id: /analytics/product_metrics/web/translation/1.0.0
$schema: 'https://json-schema.org/draft-07/schema#'
type: object
allOf:
  - $ref: /fragment/analytics/product_metrics/common/x.x.x
  - $ref: /fragment/analytics/product_metrics/web/x.x.x
  - $ref: /fragment/analytics/product_metrics/translation/1.0.0
```

--------------------------------

### Querying the Experiment Journal Database

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Troubleshooting

SQL commands to query the instruments_history table in the Test Kitchen production database. Requires production Kubernetes access.

```sql
stat1010.eqiad.wmnet $ mysql -h an-mariadb1001.eqiad.wmnet -u test_kitchen_production -p
mysql> USE test_kitchen_production;
DESCRIBE instruments_history
SELECT * FROM instruments_history WHERE <where clause here>\G;
```

--------------------------------

### Override Enrollment via URL Query Parameter

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Conduct_an_experiment

Example of using a URL query parameter to force enrollment in a specific experiment group for the current page view.

```text
?mpo=larger-default-font-size:x-large
```

--------------------------------

### Submit Click Event with Java SDK

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/SDK/Java_SDK

Use this snippet to submit a click event using the Test Kitchen base schemas. It requires instantiation of a MetricsClient and provides parameters for client and interaction data.

```java
// Parameters derived from client at instantiation of the Metrics Client object with options to pass in dynamic arguments at the time of event submission
ClientData clientData = new ClientData(
   agentData,
   pageData,
   mediawikiData,
   performerData,
);
InteractionData interactionData = new InteractionData(
   'action_value',
   'action_subtype_value',
   'action_source_value',
   'action_context_value',
);

metricsClient.submitClick(clientData, interactionData);

```

--------------------------------

### Initialize Experiment with Custom Schema and Stream

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Conduct_an_experiment

Overrides the default schema and stream for an experiment to ensure data is routed to the correct analytics destination.

```javascript
const experiment = mw.testKitchen.getExperiment( EXPERIMENT_NAME );
experiment.setSchema( '/analytics/product_metrics/web/translation/1.4.2' );
experiment.setStream( 'mediawiki.product_metrics.translation_mint_for_readers.experiments' );
```

--------------------------------

### Query Event Data in Hive using spark3-sql

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Measure_product_health

Use `spark3-sql` to query Hive tables for instrument data. This example counts events from the `product_metrics_web_base` table for a specific date.

```bash
$ spark3-sql
$ select count(*) from event.product_metrics_web_base where year = 2025 and month = 11 and day = 05;


```

--------------------------------

### Update Java Client Library Version

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Deploy_client_libraries

Example of updating the version number in the Maven project's pom file for a major version bump of the Java client library.

```xml
<groupId>org.wikimedia.metrics</groupId>
<artifactId>metrics-platform</artifactId>
<version>3.0-SNAPSHOT</version>
```

--------------------------------

### Querying Nested JSON Example

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Decision_Records/Increase_action_context_limit

Demonstrates a verbose and error-prone SQL-like query for extracting data from a deeply nested JSON field, highlighting the difficulties caused by data stuffing.

```sql
CAST(GET_JSON_OBJECT(action_context, '$.timing_ms') AS INT)
```

--------------------------------

### Good Use of action_context: Article Count

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Decision_Records/Increase_action_context_limit

Example demonstrating how to use action_context to record the number of articles in a reading list when a user adds another. The context captures the article count.

```json
{"action": "click", "action_subtype": "save_article_to_reading_list", "action_context": {"article_count": <INT>}}
```

--------------------------------

### Configure Event Stream in ext-EventStreamConfig.php

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Conduct_an_experiment

Define the stream name, schema, and producer settings including edge unique configuration.

```php
'wgEventStreams' => [
	'default' => [
        // ...

        // Stream name.
        'mediawiki_product_metrics_translation_mint_for_readers_experiments' => [
            // Schema name.
            'schema_title' => 'analytics/product_metrics/web/translation',
            'destination_event_service' => 'eventgate-analytics-external',
            'producers' => [
                'eventgate' => [
                    'enrich_fields_from_http_headers' => [
                        // Collect the user agent.
                        // Disabled by default.
                        'http.request_headers.user-agent' => 'user-agent',
                    ],
                    // Target logged-out users.
                    'use_edge_uniques' => true,
                ],
                'metrics_platform_client' => [
                    // Contextual attributes.
                    // See https://wikitech.wikimedia.org/wiki/Experimentation_Lab/Contextual_attributes
                    // NOTE `agent_client_platform` and `agent_client_platform_family`
                    //      are automatically added.
                    'provide_values' => [
                        // We recommend collecting `performer_is_logged_in` and `performer_is_temp` at the same time.
                        // See https://phabricator.wikimedia.org/T374812#10953216
                        'performer_is_logged_in',
                        'performer_is_temp',

                        'performer_pageview_id',
                        'mediawiki_database',
                    ],
                ],
            ],
        ],
    ],
],
```

--------------------------------

### Enable Contextual Attributes in Event Stream Configuration

Source: https://wikitech.wikimedia.org/wiki/Test_Kitchen/Contextual_attributes

Configure an event stream to collect specific contextual attributes by listing them in the 'provide_values' array. This example enables 'page_id', 'page_title', 'performer_is_logged_in', and 'performer_is_temp'.

```php
// …
'mediawiki.interwiki_link_hover' => [
    'schema_title' => 'analytics/product_metrics/web/base',
    'destination_event_service' => 'eventgate-analytics-external',
    'producers' => [
        'metrics_platform_client' => [
            // Contextual attributes to add to the event before it is submitted to this stream.
            'provide_values' => [
                "page_id",
                "page_title",

                // We recommend collecting the performer_is_logged_in and performer_is_temp
                // attributes at the same time. See https://phabricator.wikimedia.org/T374812#10953216
                "performer_is_logged_in",
                "performer_is_temp",
            ],
        ],
    ],
],
// …

```
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