11 KiB
WooCommerce Performance Tests
Automated k6 performance tests for WooCommerce. To be used for benchmarking performance (both single user and under load) by simulating and measuring the response time of HTTP requests.
Table of contents
Pre-requisites
Install k6
To install k6 on macOS using Homebrew
brew install k6
For other platforms please see the k6 installation guide.
Alternatively you can use the k6 docker image to execute tests.
docker pull loadimpact/k6
Configuration
Test Environment
Before using the tests a test environment is needed to run against.
In the WooCommerce e2e tests there is a Docker Initialization Script init-sample-products.sh that will set up a shop with sample products imported and the shop settings (payment method, permalinks, address etc) needed for the tests already set. It is recommended using this if to just see the tests in action.
npx wc-e2e docker:up ./tests/e2e/docker/init-sample-products.sh
If using a different environment the details can be changed in config.js.
Config Variables
config.js comes with some example values for using with the suggested local test environment. If using a different environment be sure to update the values.
Config Variables List
| Variable | Used for | Is also env variable? |
|---|---|---|
| base_url | base URL of the test environment | yes __ENV.URL |
| base_host | base host of the test environment (for use in headers) | yes __ENV.HOST |
| admin_username | username for admin user | yes __ENV.A_USER |
| admin_password | password for admin user | yes __ENV.A_PW |
| customer_username | username for customer user | yes __ENV.C_USER |
| customer_password | password for customer user | yes __ENV.C_PW |
| addresses_customer_billing_* | billing address details for existing customer user | no |
| addresses_guest_billing_* | billing address details for guest customer user | no |
| payment_method | payment method (currently only cod supported) |
no |
| product_sku | SKU of product to be used in cart and checkout flow | yes __ENV.P_SKU |
| product_url | the product-name portion of product permalink of the product to be used in cart and checkout flow |
yes __ENV.P_URL |
| product_id | the product ID of of product to be used in cart and checkout flow | yes __ENV.P_ID |
| product_search_term | search term to return product to be used in cart and checkout flow | yes __ENV.P_TERM |
| coupon_code | coupon code to be used in applying coupon flow | yes __ENV.P_COUPON |
| add_product_title | title of product to be added in merchant add product flow | no |
| add_product_regular_price | regular price of product to be added in merchant add product flow | no |
| think_time_min | minimum sleep time (in seconds) between each request | no |
| think_time_max | maximum sleep time (in seconds) between each request | no |
Running Tests
When refering to running k6 tests usually this means executing the test scenario. The test scenario file in turn determines which requests we run and how much load will be applied to them. It is also possible to execute individual test files containing requests and pass in scenario config as a CLI flag but scenario files allow for more configuration options.
Running Indvidual Tests
To execute an individual test file (for example requests/shopper/shop-page.js) containing requests.
CLI k6 run requests/shopper/shop-page.js
Docker docker run --network="host" -v /[YOUR LOCAL WC DIRECTORY FULL PATH]/requests:/requests -it loadimpact/k6 run /requests/shopper/shop-page.js
This will run the individual test for 1 iteration.
Running Scenarios
Included in the tests folder are some sample scenarios that can be ran or used as a starting point to be modified to suit the context in which tests are being ran.
simple-all-shopper-requests.js and simple-all-merchant-requests.js are included scenarios that use the per-vu-iterations scenario executor type to run each request sequentially for 1 iteration to make sure they are working.
example-all-requests-ramping-vus.js and example-all-requests-arrival-rate.js are included example scenarios for load testing that use the ramping-vus and ramping-arrival-rate scenario executor types to run all the requests under load of multiple virtual users. These scenarios can be modified to suit the load profile for the context that the tests will be ran.
Another aspect that affects the traffic pattern of the tests is the amount of “Think Time” in between requests. In real world usage of an application users will spend some amount of time before doing some action. For some situations there will be a need to simulate this as part of the test traffic and it is common to have this as part of load tests.
To do this a sleep step is included between each request sleep(randomIntBetween(`${think_time_min}`, `${think_time_max}`)).
The amount of think time can be controlled from config.js.
Note: It’s important to note to be very careful when adding load to a scenario. By accident a dangerous amount of load could be ran aginst the test environment that could effectively be like a denial-of-service attack on the test environment. Also important to consider any other consequences of running large load such as triggering of emails.
To execute a test scenario (for example tests/simple-all-shopper-requests.js).
CLI k6 run tests/simple-all-shopper-requests.js
Docker docker run --network="host" -v /[YOUR LOCAL WC DIRECTORY FULL PATH]/tests:/tests -it loadimpact/k6 run /tests/simple-all-shopper-requests.js
Debugging Tests
To help with getting a test working, the --http-debug="full" flag prints to console the full log of requests and their responses. It is also useful to use console.log() to print messages when debugging.
User Agent
k6 adds a user agent to requests, for example User-Agent: k6/0.33.0 (https://k6.io/) which makes it easier to understand what load is coming from k6 synthetically generating it versus real user load when looking at server logs.
Results Output
Basic Results
By default when running the test using k6 run, there is an aggregated summary report at the end of the test.
InfluxDB and Grafana
See this guide for more details
Writing Tests
Capturing Requests
k6 tests rely on HTTP requests in order to test the backend. They can either be constructed from scratch, by using the k6 recorder, or by converting a HAR file.
The k6 recorder is a browser extension which captures http requests generated as you perform actions in a tab. It generates a test with all the HTTP requests from your actions which can then be modified to make it execuatable.
Alternatively any application which captures HTTP requests can be used to figure out the requests to include in a test such as the network section within browser developer tools.
Tests could also be created to simulate API requests.
Static Assets
The tests only simulate the HTTP requests and do not include static assets requests (fonts, images, css, js etc).
Including them would increase the size and complexity of the tests.
Although static resources do affect the bandwidth and the overall response time for the user, they should have a smaller impact on the server load and aren’t usually as intensive on the server as running code.
In additional any use of CDNs, cache settings, and themes used would also vary from site to site.
Request Headers
Every HTTP requests tested includes the headers.
To make it easier to manage the headers they have been moved to a separate file so any changes can be made to all the requests at once.
In headers.js the common headers are grouped by type and then can be imported in for use in the requests. However if an individual request uniquely needs a specific header this can still be added in as an extra member of the headers object literal of that request.
Correlation
To make a test work so it can be ran reliably multiple times usually there is a need to correlate any dynamic data in the test. This means extracting one or more values from the response of one request and then reusing them in subsequent requests.
An example of this is the woocommerce-process-checkout-nonce . This is returned in the response of the /checkout GET request and is passed into the /?wc-ajax=checkout POST request.
A value can be correlated by using k6 selector .find to extract the data from a response by matching an element. Alternatively for extracting data from a response unsuitable for using selectors k6 has a findBetween utility that makes its easier by just having to provide the left and right boundaries of the data.
Groups
Groups are used to organize common logic in the test scripts and can help with the test result analysis. For example the group "Proceed to checkout" groups together multiple requests triggered by this action.
Checks
Checks are like asserts but they don’t stop the tests if they record a failure (for example in a load test with 1000s of iterations of a request this allows for an isolated flakey iteration to not stop test execution).
All requests have had checks for at least a 200 http status repsonse added and most also have an additional check for a string contained in the response body.
Custom Metrics
By default the built-in metrics group the HTTP requests timings so it isn't possible drill down into individual HTTP request timings. To enable seeing these individual timing in the aggregated summary report it is possible to create a custom metric for each request.
The tests name them after the requests which the metric represents.
Other Resources
k6 documention is a very useful resource for test creation and execution.