k6

1. Load Tests as JavaScript Code
Load Testing with K6 Framework
Software University
https://softuni.bg
Svetlin Nakov, PhD
Technical Trainer and Inspirer
Co-Founder @ SoftUni
https://softuni.org

2.  Software engineer, trainer, entrepreneur,
inspirer, PhD, author of 15+ technical books
 3 successful tech educational initiatives (150,000+ students)
About Dr. Svetlin Nakov
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3. Overview
Performance Testing
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4.  Performance testing
 Determine whether software meets speed, scalability and
stability requirements under expected workloads
 Load testing & stress testing tools
 Record scenarios (e. g. login  place an order  logout)
 Execute the scenarios with multiple virtual users (e. g. 200 users)
 Tools can be configuration-driven (JMeter, LoadRunner) or
code-driven (k6, Locust, Gatling)
Performance Testing: Overview
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5.  Load testing
 Examine the performance for a specific expected load
 E. g. run a scenario with 200 users in parallel for 5 minutes
 Expect the average load time < 500 ms
 Stress testing
 Test app stability when running under extreme conditions
 Goal: understand at which level the app can crash
 E. g. 5K users for 3 minutes  check how many succeed
Performance Testing: Types
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6. "K6" Load Testing Tool
Code-Based Performance Testing

7.  k6 is modern, open-source load testing tool – https://k6.io
 Testing framework based on JavaScript (very powerful)
 Local & cloud script executor based on Go (high performance)
 Script recorder (Chrome plugin)  generates JS code
 Tests are plain JavaScript code
 No XML configuration, no need for complex UI
 Very powerful: JavaScript can test anything
 Easy to use with continuous integration scripts
K6 Load Testing Tool
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8.  Installing k6 console app:
 https://github.com/loadimpact/k6/releases
 Simple testing script:
 Running the script (just once)
K6: Install and Run
k6 run simple.js
import http from 'k6/http';
export default function () {
http.get('https://nakov-mvc-node-app.herokuapp.com');
}
simple.js
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9. K6: Script Execution
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10.  Load test: 50 virtual users for 15 seconds:
 Stress test: 3000 virtual users for 30 seconds:
 Note this will flood most Web apps
 Unless a DoS protection is implemented
 Warning: flooding web apps (which you do not own) might be
illegal in some countries!
K6: Load Testing and Stress Testing
k6 --vus 50 --duration 15s run simple.js
k6 --vus 3000 --duration 30s run simple.js
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11.  k6 has test recorder (Chrome plugin)
 Record testing scenarios (HTTP
requests) from the Web browser
 Generates HTTP archives (HAR files)
 Edit the recorded scripts at k6 cloud
 Edit the scenarios in a visual editor
 Or edit the JavaScript code behind
 https://app.k6.io – free limited access
K6 Test Recorder
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12. The K6 Cloud
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13.  Users in the real world behave like this:
 Open a page  wait  open another page  wait  fill a form
 submit the form  wait  open another page  …
Writing K6 Scripts for Real-World Scenarios
http.get("https://nakov-mvc-node-app.herokuapp.com/");
sleep(2);
http.get("https://nakov-mvc-node-app.herokuapp.com/students");
sleep(3);
http.get("https://nakov-mvc-node-app.herokuapp.com/add-student");
sleep(3);
let body = { name: "New student" + uniqueNum, email: "new@gmail.com" };
http.post("https://nakov-mvc-node-app.herokuapp.com/add-student", body);
sleep(2);
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14.  Checks are like assertions in unit testing:
K6: Checks
import { check } from "k6";
import http from "k6/http";
export default function() {
let res = http.get("https://nakov-mvc-node-app.herokuapp.com/");
check(res, {
'HTTP status == 200': res => res.status == 200,
'Page heading': res =>
res.body.includes('<h1>Students Registry</h1>')
});
}
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15.  Thresholds define pass / fail criteria for the test
K6: Thresholds
export let options = {
thresholds: {
// 95% of requests must finish within 500 ms & 99% within 1500 ms
http_req_duration: ['p(95) < 500', 'p(99) < 1500'],
},
};
export default function performanceTest() {
…
}
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16.  Sample performance testing scenario for the "Students Registry"
app: https://nakov-mvc-node-app.herokuapp.com
1. Open the [Home] page & wait 2 secs
2. Open the [Students] page & wait 3 secs
3. Open the [Add Students] page & wait 3 secs
4. Submit the [Add Students] form & wait 2 secs
 Code: https://gist.github.com/nakov/79f5e28a8b8c91f73c26eb55a89d80bc
K6: Testing Script with Waits Example
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k6 --vus 200 --duration 10s run load-test-with-waits.js

17.  Run k6 with
5000 virtual
users for 20
secs and see
the results:
K6: Full Performance Testing Script Example
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18. © SoftUni – https://softuni.org