Implementation:Webdriverio Webdriverio Selector Testing

Knowledge Sources	Webdriverio_Webdriverio
Domains	Mobile_Testing, Selector_Validation
Last Updated	2026-02-12 00:00 GMT

Overview

The Selector Testing module tests optimized selectors against live browser elements to verify they find the correct elements and measure their performance.

Description

The testOptimizedSelector function calls the browser's findElement or findElements protocol method using the provided strategy (accessibility id, -ios predicate string, or -ios class chain) and value. It measures the execution duration via high-resolution timing and returns element references with timing data. In debug mode, the function provides extensive step-by-step logging, including page source analysis when elements are not found and automatic retry logic. An internal helper extractMatchingElementsFromPageSource searches the raw page source XML using regex patterns to identify potential matches for debugging purposes.

Usage

This function is called by the optimizer module's step 4 to verify that a proposed optimized selector actually finds the target element(s) before recommending the replacement.

Code Reference

Source Location

Repository: Webdriverio_Webdriverio
File: packages/wdio-appium-service/src/mobileSelectorPerformanceOptimizer/utils/selector-testing.ts
Lines: 112-247

Signature

export async function testOptimizedSelector(
    browser: WebdriverIO.Browser | WebdriverIO.MultiRemoteBrowser,
    using: string,
    value: string,
    isMultiple: boolean,
    debug?: boolean
): Promise<{ elementRefs: Array<{ [key: string]: string }>, duration: number } | null>

Import

import { testOptimizedSelector } from './utils/selector-testing.js'

I/O Contract

Inputs

Name	Type	Required	Description
browser	WebdriverIO.MultiRemoteBrowser	Yes	Browser instance with findElement/findElements protocol methods
using	`string`	Yes	Locator strategy (e.g., 'accessibility id', '-ios predicate string', '-ios class chain')
value	`string`	Yes	Selector value for the given strategy
isMultiple	`boolean`	Yes	If true, uses findElements; if false, uses findElement
debug	`boolean`	No	Enables detailed step-by-step debug logging and retry logic; defaults to false

Outputs

Name	Type	Description
return	null>	Object containing an array of element reference objects and the execution duration in milliseconds; returns null if an exception occurs during element finding

Usage Examples

Testing an Accessibility ID Selector

import { testOptimizedSelector } from './selector-testing.js'

const result = await testOptimizedSelector(
    browser,
    'accessibility id',
    'Login',
    false,   // single element
    false    // no debug
)

if (result && result.elementRefs.length > 0) {
    console.log(`Found element in ${result.duration.toFixed(2)}ms`)
} else {
    console.log('Element not found with optimized selector')
}

Testing a Predicate String for Multiple Elements

const result = await testOptimizedSelector(
    browser,
    '-ios predicate string',
    "type == 'XCUIElementTypeCell' AND visible == 'true'",
    true,    // multiple elements
    true     // enable debug logging
)

if (result) {
    console.log(`Found ${result.elementRefs.length} element(s) in ${result.duration.toFixed(2)}ms`)
}

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Principle

Implementation

Heuristic

Environment