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How to use stopTracing method in Playwright Internal

Best JavaScript code snippet using playwright-internal

trace.js

...82                            .then(function () {83                                reloadRunningTracingData();84                            });85                    }86                    function stopTracing() {87                        var data = {88                            traceConfigurationId: scope.trace.traceConfiguration.id89                        };90                        stopTraceTimer();91                        trace.stopTracing(data)92                            .then(function () {93                                reloadTracingData();94                                reloadRunningTracingData();95                            });96                    }97                    function getTraceById(traceId) {98                        var itemToReturn = null;99                        scope.traceResults.forEach(function (item) {100                            if (item.id === traceId) {101                                itemToReturn = item;102                            }103                        });104                        return itemToReturn;105                    }...

LogData.js

Source: LogData.js

...89        this.functionExit = function (iid, returnVal, wrappedExceptionVal) {90            logEvent('E,' + sandbox.sid + "," + iid + "," + getValue(returnVal) + "," + getType(returnVal));91        };92        this.endExecution = function () {93            traceWriter.stopTracing();94            var tw = new sandbox.TraceWriter("strings.json");95            tw.logToFile(JSON.stringify(stringList)+"\n");96            tw.stopTracing();97            tw = new sandbox.TraceWriter("smap.json");98            tw.logToFile(JSON.stringify(sandbox.smap)+"\n");99            tw.stopTracing();100        };101        this.runInstrumentedFunctionBody = function (iid, f, functionIid) {102            return false;103        };104        /**105         * onReady is useful if your analysis is running on node.js (i.e., via the direct.js or jalangi.js commands)106         * and needs to complete some asynchronous initialization before the instrumented program starts.  In such a107         * case, once the initialization is complete, invoke the cb function to start execution of the instrumented108         * program.109         *110         * Note that this callback is not useful in the browser, as Jalangi has no control over when the111         * instrumented program runs there.112         * @param cb113         */...

browserDispatcher.js

Source: browserDispatcher.js

...62    if (!this._object.options.isChromium) throw new Error(`Tracing is only available in Chromium`);63    const crBrowser = this._object;64    await crBrowser.startTracing(params.page ? params.page._object : undefined, params);65  }66  async stopTracing() {67    if (!this._object.options.isChromium) throw new Error(`Tracing is only available in Chromium`);68    const crBrowser = this._object;69    const buffer = await crBrowser.stopTracing();70    return {71      binary: buffer.toString('base64')72    };73  }74} // This class implements multiplexing browser dispatchers over a single Browser instance.75exports.BrowserDispatcher = BrowserDispatcher;76class ConnectedBrowserDispatcher extends _dispatcher.Dispatcher {77  constructor(scope, browser) {78    super(scope, browser, 'Browser', {79      version: browser.version(),80      name: browser.options.name81    }, true); // When we have a remotely-connected browser, each client gets a fresh Selector instance,82    // so that two clients do not interfere between each other.83    this._type_Browser = true;84    this._contexts = new Set();85    this.selectors = void 0;86    this.selectors = new _selectors.Selectors();87  }88  async newContext(params, metadata) {89    if (params.recordVideo) params.recordVideo.dir = this._object.options.artifactsDir;90    const context = await this._object.newContext(params);91    this._contexts.add(context);92    context._setSelectors(this.selectors);93    context.on(_browserContext.BrowserContext.Events.Close, () => this._contexts.delete(context));94    if (params.storageState) await context.setStorageState(metadata, params.storageState);95    return {96      context: new _browserContextDispatcher.BrowserContextDispatcher(this._scope, context)97    };98  }99  async close() {// Client should not send us Browser.close.100  }101  async killForTests() {// Client should not send us Browser.killForTests.102  }103  async newBrowserCDPSession() {104    if (!this._object.options.isChromium) throw new Error(`CDP session is only available in Chromium`);105    const crBrowser = this._object;106    return {107      session: new _cdpSessionDispatcher.CDPSessionDispatcher(this._scope, await crBrowser.newBrowserCDPSession())108    };109  }110  async startTracing(params) {111    if (!this._object.options.isChromium) throw new Error(`Tracing is only available in Chromium`);112    const crBrowser = this._object;113    await crBrowser.startTracing(params.page ? params.page._object : undefined, params);114  }115  async stopTracing() {116    if (!this._object.options.isChromium) throw new Error(`Tracing is only available in Chromium`);117    const crBrowser = this._object;118    const buffer = await crBrowser.stopTracing();119    return {120      binary: buffer.toString('base64')121    };122  }123  async cleanupContexts() {124    await Promise.all(Array.from(this._contexts).map(context => context.close((0, _instrumentation.internalCallMetadata)())));125  }126}...

watching.js

Source: watching.js

...93    await page.tracing.start(args);94  }95  const stopTracing = async () => {96    if (isPlaywright) {97      return await context.browser().stopTracing();98    } else {99      return await page.tracing.stop();100    }101  }102  return async () => {103    const tracing = JSON.parse((await stopTracing()).toString());104    if (IS_DEBUG) {105      fs.writeFileSync(path.resolve(__dirname, './tracing.json'), JSON.stringify(tracing));106    }107    return tracing.traceEvents;108  }109};110const writeCoverage = async (page, isPlaywright) => {111  await Promise.all([112    page.coverage.startJSCoverage(),113    page.coverage.startCSSCoverage()114  ]);115  return async () => {116    const [js, css] = await Promise.all([117      page.coverage.stopJSCoverage(),...

index.js

Source: index.js

...50        // do nothing51      }52    });53  }54  stopTracing();55}56ViewModel.prototype.$watch = function(getter, callback, meta) {57  return new Observer(this, getter, callback, meta);58};59/**60 * initialize the state of ViewModel instance61 * @param {ViewModel} vm ViewModel instance62 * @param {Object} data the data to be observe63 */64function initState(vm, data) {65  startTracing(PHASE_INIT_STATE);66  startTracing(PHASE_INIT_DATA_GET_DATA);67  if (typeof data === 'function') {68    data = data.call(vm, vm);69  }70  stopTracing(); // PHASE_INIT_DATA_GET_DATA71  startTracing(PHASE_INIT_DATA_PROXY);72  Object.keys(data).forEach(key => proxy(vm, data, key));73  stopTracing(); // PHASE_INIT_DATA_PROXY74  startTracing(PHASE_INIT_DATA_OBSERVE);75  Subject.of(data);76  stopTracing(); // PHASE_INIT_DATA_OBSERVE77  stopTracing(); // PHASE_INIT_STATE78}79/**80 * proxy data81 * @param {ViewModel} target ViewModel instance82 * @param {Object} source the data to be proxy83 * @param {String} key the key to be proxy84 */85function proxy(target, source, key) {86  Object.defineProperty(target, key, {87    enumerable: false,88    configurable: true,89    get() {90      return source[key];91    },92    set(value) {93      source[key] = value;94    }95  });96}...

driver.js

Source: driver.js

...22  const driver = await createDriver({ port: 3000 })23  driver.on('status', handler)24  await driver.loadFile('test/fixtures/fast.js')25  await driver.startTracing()26  await driver.stopTracing()27  t.true(Tracing.start.calledOnce)28  t.snapshot(handler.args)29  driver.close()30})31test('collect events', async t => {32  const driver = await createDriver({ port: 3000 })33  await driver.loadFile('test/fixtures/fast.js')34  await driver.startTracing()35  await delay(0)36  await driver.stopTracing()37  t.true(Tracing.callbacks.dataCollected.calledOnce)38  t.snapshot(Tracing.callbacks.dataCollected.args)39  driver.close()...

Using AI Code Generation

1const { chromium } = require('playwright');2(async () => {3  const browser = await chromium.launch();4  const context = await browser.newContext();5  const page = await context.newPage();6  await page.tracing.start({ screenshots: true, snapshots: true });7  await page.tracing.stop({ path: 'trace.zip' });8  await browser.close();9})();10const { chromium } = require('playwright');11(async () => {12  const browser = await chromium.launch();13  const context = await browser.newContext();14  const page = await context.newPage();15  await page.tracing.start({ screenshots: true, snapshots: true });16  await page.tracing.stop({ path: 'trace.zip' });17  await browser.close();18})();19const { chromium } = require('playwright');20(async () => {21  const browser = await chromium.launch();22  const context = await browser.newContext();23  const page = await context.newPage();24  await page.tracing.start({ screenshots: true, snapshots: true });25  await page.tracing.stop({ path: 'trace.zip' });26  await browser.close();27})();28const { chromium } = require('playwright');29(async () => {30  const browser = await chromium.launch();31  const context = await browser.newContext();32  const page = await context.newPage();33  await page.tracing.start({ screenshots: true, snapshots: true });34  await page.tracing.stop({ path: 'trace.zip' });35  await browser.close();36})();37const { chromium } = require('playwright');38(async () => {39  const browser = await chromium.launch();40  const context = await browser.newContext();41  const page = await context.newPage();42  await page.tracing.start({ screenshots: true, snapshots: true });43  await page.tracing.stop({

Using AI Code Generation

1const { chromium } = require('playwright');2(async () => {3  const browser = await chromium.launch({ headless: false });4  const context = await browser.newContext();5  const page = await context.newPage();6  await page.tracing.start({ screenshots: true, snapshots: true });7  await page.tracing.stop({ path: 'trace.zip' });8  await browser.close();9})();10In the above code, we are using the tracing.stop() method of Playwright’s internal API to stop the tracing. The tracing.stop() method takes

Using AI Code Generation

1const { chromium } = require('playwright');2(async () => {3  const browser = await chromium.launch({ headless: false });4  const context = await browser.newContext();5  const page = await context.newPage();6  await page.tracing.start({ screenshots: true, snapshots: true });7  await page.tracing.stop({ path: 'trace.zip' });8  await browser.close();9})();10const { chromium } = require('playwright');11(async () => {12  const browser = await chromium.launch({ headless: false });13  const context = await browser.newContext();14  const page = await context.newPage();15  await page.tracing.start({ screenshots: true, snapshots: true });16  await page.tracing.stop({ path: 'trace2.zip' });17  await browser.close();18})();19const { chromium } = require('playwright');20(async () => {21  const browser = await chromium.launch({ headless: false });22  const context = await browser.newContext();23  const page = await context.newPage();24  await page.tracing.start({ screenshots: true, snapshots: true });25  await page.tracing.stop({ path: 'trace3.zip' });26  await browser.close();27})();28const { chromium } = require('playwright');29(async () => {30  const browser = await chromium.launch({ headless: false });31  const context = await browser.newContext();32  const page = await context.newPage();33  await page.tracing.start({ screenshots: true, snapshots: true });34  await page.tracing.stop({ path: 'trace4.zip' });35  await browser.close();36})();37const { chromium } = require('playwright');38(async () => {39  const browser = await chromium.launch({ headless: false });40  const context = await browser.newContext();41  const page = await context.newPage();

Using AI Code Generation

1const { chromium } = require('playwright');2(async () => {3  const browser = await chromium.launch({ headless: false });4  const context = await browser.newContext();5  const page = await context.newPage();6  await page.tracing.start({ screenshots: true, snapshots: true });7  await page.tracing.stop();8  await browser.close();9})();10const { chromium } = require('playwright');11(async () => {12  const browser = await chromium.launch({ headless: false });13  const context = await browser.newContext();14  const page = await context.newPage();15  await page.tracing.start({ screenshots: true, snapshots: true });16  await page.tracing.stop();17  await browser.close();18})();19const { chromium } = require('playwright');20(async () => {21  const browser = await chromium.launch({ headless: false });22  const context = await browser.newContext();23  const page = await context.newPage();24  await page.tracing.start({ screenshots: true, snapshots: true });25  await page.tracing.stop();26  await browser.close();27})();28const { chromium } = require('playwright');29(async () => {30  const browser = await chromium.launch({ headless: false });31  const context = await browser.newContext();32  const page = await context.newPage();33  await page.tracing.start({ screenshots: true, snapshots: true });34  await page.tracing.stop();35  await browser.close();36})();37const { chromium } = require('playwright');38(async () => {39  const browser = await chromium.launch({ headless: false });40  const context = await browser.newContext();41  const page = await context.newPage();

Using AI Code Generation

1const playwright = require('playwright');2(async () => {3  const browser = await playwright.webkit.launch();4  const context = await browser.newContext();5  const page = await context.newPage();6  await page.tracing.start({ screenshots: true, snapshots: true });7  await page.tracing.stop({ path: 'trace.zip' });8  await browser.close();9})();10const playwright = require('playwright');11(async () => {12  const browser = await playwright.webkit.launch();13  const context = await browser.newContext();14  const page = await context.newPage();15  await page.tracing.start({ screenshots: true, snapshots: true });16  await page.tracing.stop({ path: 'trace.zip' });17  await browser.close();18})();19const playwright = require('playwright');20(async () => {21  const browser = await playwright.webkit.launch();22  const context = await browser.newContext();23  const page = await context.newPage();24  await page.tracing.start({ screenshots: true, snapshots: true });25  await page.tracing.stop({ path: 'trace.zip' });26  await browser.close();27})();28const playwright = require('playwright');29(async () => {30  const browser = await playwright.webkit.launch();31  const context = await browser.newContext();32  const page = await context.newPage();33  await page.tracing.start({ screenshots: true, snapshots: true });34  await page.tracing.stop({ path: 'trace.zip' });35  await browser.close();36})();37const playwright = require('playwright');38(async () => {39  const browser = await playwright.webkit.launch();40  const context = await browser.newContext();41  const page = await context.newPage();42  await page.tracing.start({ screenshots: true, snapshots: true });43  await page.tracing.stop({ path: 'trace.zip

Using AI Code Generation

1const { chromium } = require('playwright');2(async () => {3  const browser = await chromium.launch();4  const page = await browser.newPage();5  const trace = await page.context().newTracing({ screenshots: true, snapshots: true });6  await trace.start({ screenshots: true, snapshots: true });7  await page.click('text=Get started');8  await trace.stop({ path: 'trace.zip' });9  await browser.close();10})();11const { chromium } = require('playwright');12(async () => {13  const browser = await chromium.launch();14  const page = await browser.newPage();15  await page.context().startTracing({ screenshots: true, snapshots: true });16  await page.click('text=Get started');17  await page.context().stopTracing({ path: 'trace.zip' });18  await browser.close();19})();20const { chromium } = require('playwright');21(async () => {22  const browser = await chromium.launch();23  const page = await browser.newPage();24  await page.context().startTracing({ screenshots: true, snapshots: true });25  await page.click('text=Get started');26  await page.context().stopTracing({ path: 'trace.zip' });27  await browser.close();28})();29const { chromium } = require('playwright');30(async () => {31  const browser = await chromium.launch();32  const page = await browser.newPage();33  await page.context().startTracing({ screenshots: true, snapshots: true });34  await page.click('text=Get started');35  await page.context().stopTracing({ path: 'trace.zip' });36  await browser.close();37})();38const { chromium } = require('playwright');39(async () => {40  const browser = await chromium.launch();41  const page = await browser.newPage();42  await page.context().startTracing({ screenshots: true, snapshots: true });43  await page.click('text

Using AI Code Generation

1const { chromium } = require('playwright');2const { stopTracing } = require('playwright/lib/server/chromium');3(async () => {4  const browser = await chromium.launch({headless: false});5  const context = await browser.newContext();6  const page = await context.newPage();7  await page.screenshot({ path: 'google.png' });8  await stopTracing(page);9  await browser.close();10})();11const { chromium } = require('playwright');12const { stopTracing } = require('playwright/lib/server/chromium');13(async () => {14  const browser = await chromium.launch({headless: false});15  const context = await browser.newContext();16  const page = await context.newPage();17  await page.screenshot({ path: 'google.png' });18  await stopTracing(page);19  await browser.close();20})();21const { chromium } = require('playwright');22const { stopTracing } = require('playwright/lib/server/chromium');23(async () => {24  const browser = await chromium.launch({headless: false});25  const context = await browser.newContext();26  const page = await context.newPage();27  await page.screenshot({ path: 'google.png' });28  await stopTracing(page);29  await browser.close();30})();31const { chromium } = require('playwright');32const { stopTracing } = require('playwright/lib/server/chromium');33(async () => {34  const browser = await chromium.launch({headless: false});35  const context = await browser.newContext();36  const page = await context.newPage();37  await page.screenshot({ path: 'google.png' });38  await stopTracing(page);39  await browser.close();40})();41const { chromium } = require('playwright');42const { stopTracing } = require('playwright/lib/server/chromium');43(async () => {44  const browser = await chromium.launch({headless: false});

Using AI Code Generation

1const playwright = require('playwright');2const { trace } = require('playwright/lib/server/trace/recorder');3const { chromium } = require('playwright');4const fs = require('fs');5(async () => {6  const browser = await chromium.launch({ headless: false });7  const context = await browser.newContext();8  const page = await context.newPage();9  await page.fill('input[name="q"]', 'Hello world');10  await page.click('input[value="Google Search"]');11  await page.waitForSelector('text=Hello world');12  await page.screenshot({ path: 'example.png' });13  const trace = await context.tracing.stop({ path: 'trace.zip' });14  await browser.close();15})();16const playwright = require('playwright');17const { trace } = require('playwright/lib/server/trace/recorder');18const { chromium } = require('playwright');19const fs = require('fs');20(async () => {21  const browser = await chromium.launch({ headless: false });22  const context = await browser.newContext();23  const page = await context.newPage();24  await page.fill('input[name="q"]', 'Hello world');25  await page.click('input[value="Google Search"]');26  await page.waitForSelector('text=Hello world');27  await page.screenshot({ path: 'example.png' });28  const trace = await context.tracing.stop({ path: 'trace.zip' });29  await browser.close();30})();31const playwright = require('playwright');32const { trace } = require('playwright/lib/server/trace/recorder');33const { chromium } = require('playwright');34const fs = require('fs');35(async () => {36  const browser = await chromium.launch({ headless: false });37  const context = await browser.newContext();38  const page = await context.newPage();39  await page.fill('input[name="q"]', 'Hello world');40  await page.click('input[value="Google Search"]');41  await page.waitForSelector('text=Hello world');42  await page.screenshot({ path: 'example.png' });

StackOverFlow community discussions

Questions

Discussion

Is it possible to get the selector from a locator object in playwright?

Running Playwright in Azure Function

How to run a list of test suites in a single file concurrently in jest?

firefox browser does not start in playwright

Jest + Playwright - Test callbacks of event-based DOM library

Well this is one way, but not sure if it will work for all possible locators!.

// Get a selector from a playwright locator
import { Locator } from "@playwright/test";
export function extractSelector(locator: Locator) {
    const selector = locator.toString();
    const parts = selector.split("@");
    if (parts.length !== 2) { throw Error("extractSelector: susupect that this is not a locator"); }
    if (parts[0] !== "Locator") { throw Error("extractSelector: did not find locator"); }
    return parts[1];
}

https://stackoverflow.com/questions/72044959/is-it-possible-to-get-the-selector-from-a-locator-object-in-playwright

Assuming you are not running test with the --runinband flag, the simple answer is yes but it depends ????

There is a pretty comprehensive GitHub issue jest#6957 that explains certain cases of when tests are run concurrently or in parallel. But it seems to depend on a lot of edge cases where jest tries its best to determine the fastest way to run the tests given the circumstances.

To my knowledge there is no way to force jest to run in parallel.

Aside

Have you considered using playwright instead of puppeteer with jest? Playwright has their own internally built testing library called @playwright/test that is used in place of jest with a similar API. This library allows for explicitly defining test groups in a single file to run in parallel (i.e. test.describe.parallel) or serially (i.e. test.describe.serial). Or even to run all tests in parallel via a config option.

// parallel
test.describe.parallel('group', () => {
  test('runs in parallel 1', async ({ page }) => {});
  test('runs in parallel 2', async ({ page }) => {});
});

// serial
test.describe.serial('group', () => {
  test('runs first', async ({ page }) => {});
  test('runs second', async ({ page }) => {});
});

https://stackoverflow.com/questions/73497773/how-to-run-a-list-of-test-suites-in-a-single-file-concurrently-in-jest

I found the error. It was because of some missing libraries need. I discovered this when I downgraded playwright to version 1.9 and ran the the code then this was the error msg:

(node:12876) UnhandledPromiseRejectionWarning: browserType.launch: Host system is missing dependencies!

Some of the Universal C Runtime files cannot be found on the system. You can fix
that by installing Microsoft Visual C++ Redistributable for Visual Studio from:
https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads

Full list of missing libraries:
    vcruntime140.dll
    msvcp140.dll
Error
    at Object.captureStackTrace (D:\Projects\snkrs-play\node_modules\playwright\lib\utils\stackTrace.js:48:19)
    at Connection.sendMessageToServer (D:\Projects\snkrs-play\node_modules\playwright\lib\client\connection.js:69:48)
    at Proxy.<anonymous> (D:\Projects\snkrs-play\node_modules\playwright\lib\client\channelOwner.js:64:61)
    at D:\Projects\snkrs-play\node_modules\playwright\lib\client\browserType.js:64:67
    at BrowserType._wrapApiCall (D:\Projects\snkrs-play\node_modules\playwright\lib\client\channelOwner.js:77:34)
    at BrowserType.launch (D:\Projects\snkrs-play\node_modules\playwright\lib\client\browserType.js:55:21)
    at D:\Projects\snkrs-play\index.js:4:35
    at Object.<anonymous> (D:\Projects\snkrs-play\index.js:7:3)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:12876) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:12876) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

A list of missing libraries was provided. After successful installments, firefox ran fine. I upgraded again to version 1.10 and firefox still works.

https://stackoverflow.com/questions/66984974/firefox-browser-does-not-start-in-playwright

I found the error. It was because of some missing libraries need. I discovered this when I downgraded playwright to version 1.9 and ran the the code then this was the error msg:

(node:12876) UnhandledPromiseRejectionWarning: browserType.launch: Host system is missing dependencies!

Some of the Universal C Runtime files cannot be found on the system. You can fix
that by installing Microsoft Visual C++ Redistributable for Visual Studio from:
https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads

Full list of missing libraries:
    vcruntime140.dll
    msvcp140.dll
Error
    at Object.captureStackTrace (D:\Projects\snkrs-play\node_modules\playwright\lib\utils\stackTrace.js:48:19)
    at Connection.sendMessageToServer (D:\Projects\snkrs-play\node_modules\playwright\lib\client\connection.js:69:48)
    at Proxy.<anonymous> (D:\Projects\snkrs-play\node_modules\playwright\lib\client\channelOwner.js:64:61)
    at D:\Projects\snkrs-play\node_modules\playwright\lib\client\browserType.js:64:67
    at BrowserType._wrapApiCall (D:\Projects\snkrs-play\node_modules\playwright\lib\client\channelOwner.js:77:34)
    at BrowserType.launch (D:\Projects\snkrs-play\node_modules\playwright\lib\client\browserType.js:55:21)
    at D:\Projects\snkrs-play\index.js:4:35
    at Object.<anonymous> (D:\Projects\snkrs-play\index.js:7:3)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:12876) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:12876) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

A list of missing libraries was provided. After successful installments, firefox ran fine. I upgraded again to version 1.10 and firefox still works.

https://stackoverflow.com/questions/66984974/firefox-browser-does-not-start-in-playwright

This question is quite close to a "need more focus" question. But let's try to give it some focus:

Does Playwright has access to the cPicker object on the page? Does it has access to the window object?

Yes, you can access both cPicker and the window object inside an evaluate call.

Should I trigger the events from the HTML file itself, and in the callbacks, print in the DOM the result, in some dummy-element, and then infer from that dummy element text that the callbacks fired?

Exactly, or you can assign values to a javascript variable:

const cPicker = new ColorPicker({
  onClickOutside(e){
  },
  onInput(color){
    window['color'] = color;
  },
  onChange(color){
    window['result'] = color;
  }
})

And then

it('Should call all callbacks with correct arguments', async() => {
    await page.goto(`http://localhost:5000/tests/visual/basic.html`, {waitUntil:'load'})

    // Wait until the next frame
    await page.evaluate(() => new Promise(requestAnimationFrame))

    // Act
   
    // Assert
    const result = await page.evaluate(() => window['color']);
    // Check the value
})

https://stackoverflow.com/questions/65477895/jest-playwright-test-callbacks-of-event-based-dom-library

Blogs

Check out the latest blogs from LambdaTest on this topic:

How To Write End-To-End Tests Using Cypress App Actions

When I started writing tests with Cypress, I was always going to use the user interface to interact and change the application’s state when running tests.

Complete Tutorial On Appium Parallel Testing [With Examples]

In today’s fast-paced world, the primary goal of every business is to release their application or websites to the end users as early as possible. As a result, businesses constantly search for ways to test, measure, and improve their products. With the increase in competition, faster time to market (TTM) has become vital for any business to survive in today’s market. However, one of the possible challenges many business teams face is the release cycle time, which usually gets extended for several reasons.

Test strategy and how to communicate it

I routinely come across test strategy documents when working with customers. They are lengthy—100 pages or more—and packed with monotonous text that is routinely reused from one project to another. Yawn once more— the test halt and resume circumstances, the defect management procedure, entrance and exit criteria, unnecessary generic risks, and in fact, one often-used model replicates the requirements of textbook testing, from stress to systems integration.

How To Use WebDriverManager In Selenium

Scala Testing: A Comprehensive Guide

Before we discuss Scala testing, let us understand the fundamentals of Scala and how this programming language is a preferred choice for your development requirements.The popularity and usage of Scala are rapidly rising, evident by the ever-increasing open positions for Scala developers.

Playwright tutorial

LambdaTest’s Playwright tutorial will give you a broader idea about the Playwright automation framework, its unique features, and use cases with examples to exceed your understanding of Playwright testing. This tutorial will give A to Z guidance, from installing the Playwright framework to some best practices and advanced concepts.

Chapters:

What is Playwright : Playwright is comparatively new but has gained good popularity. Get to know some history of the Playwright with some interesting facts connected with it.
How To Install Playwright : Learn in detail about what basic configuration and dependencies are required for installing Playwright and run a test. Get a step-by-step direction for installing the Playwright automation framework.
Playwright Futuristic Features: Launched in 2020, Playwright gained huge popularity quickly because of some obliging features such as Playwright Test Generator and Inspector, Playwright Reporter, Playwright auto-waiting mechanism and etc. Read up on those features to master Playwright testing.
What is Component Testing: Component testing in Playwright is a unique feature that allows a tester to test a single component of a web application without integrating them with other elements. Learn how to perform Component testing on the Playwright automation framework.
Inputs And Buttons In Playwright: Every website has Input boxes and buttons; learn about testing inputs and buttons with different scenarios and examples.
Functions and Selectors in Playwright: Learn how to launch the Chromium browser with Playwright. Also, gain a better understanding of some important functions like “BrowserContext,” which allows you to run multiple browser sessions, and “newPage” which interacts with a page.
Handling Alerts and Dropdowns in Playwright : Playwright interact with different types of alerts and pop-ups, such as simple, confirmation, and prompt, and different types of dropdowns, such as single selector and multi-selector get your hands-on with handling alerts and dropdown in Playright testing.
Playwright vs Puppeteer: Get to know about the difference between two testing frameworks and how they are different than one another, which browsers they support, and what features they provide.
Run Playwright Tests on LambdaTest: Playwright testing with LambdaTest leverages test performance to the utmost. You can run multiple Playwright tests in Parallel with the LammbdaTest test cloud. Get a step-by-step guide to run your Playwright test on the LambdaTest platform.
Playwright Python Tutorial: Playwright automation framework support all major languages such as Python, JavaScript, TypeScript, .NET and etc. However, there are various advantages to Python end-to-end testing with Playwright because of its versatile utility. Get the hang of Playwright python testing with this chapter.
Playwright End To End Testing Tutorial: Get your hands on with Playwright end-to-end testing and learn to use some exciting features such as TraceViewer, Debugging, Networking, Component testing, Visual testing, and many more.
Playwright Video Tutorial: Watch the video tutorials on Playwright testing from experts and get a consecutive in-depth explanation of Playwright automation testing.