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Writing Tests

Testrunner Framework Support​

@wdio/visual-service is test-runner framework agnostic, which means that you can use it with all the frameworks WebdriverIO supports like:

Within your tests, you can save screenshots or match the current visual state of your application under test with a baseline. For that, the service provides custom matcher, as well as check methods:

describe('Mocha Example', () => {
    beforeEach(async () => {
        await browser.url('https://webdriver.io')
    })

    it('using visual matchers to assert against baseline', async () => {
        // Check screen to exactly match with baseline
        await expect(browser).toMatchScreenSnapshot('partialPage')
        // check an element to have a mismatch percentage of 5% with the baseline
        await expect(browser).toMatchScreenSnapshot('partialPage', 5)
        // check an element with options for `saveScreen` command
        await expect(browser).toMatchScreenSnapshot('partialPage', {
            /* some options */
        })

        // Check an element to exactly match with baseline
        await expect($('#element-id')).toMatchElementSnapshot('firstButtonElement')
        // check an element to have a mismatch percentage of 5% with the baseline
        await expect($('#element-id')).toMatchElementSnapshot('firstButtonElement', 5)
        // check an element with options for `saveElement` command
        await expect($('#element-id')).toMatchElementSnapshot('firstButtonElement', {
            /* some options */
        })

        // Check a full page screenshot match with baseline
        await expect(browser).toMatchFullPageSnapshot('fullPage')
        // Check a full page screenshot to have a mismatch percentage of 5% with the baseline
        await expect(browser).toMatchFullPageSnapshot('fullPage', 5)
        // Check a full page screenshot with options for `checkFullPageScreen` command
        await expect(browser).toMatchFullPageSnapshot('fullPage', {
            /* some options */
        })

        // Check a full page screenshot with all tab executions
        await expect(browser).toMatchTabbablePageSnapshot('check-tabbable')
        // Check a full page screenshot to have a mismatch percentage of 5% with the baseline
        await expect(browser).toMatchTabbablePageSnapshot('check-tabbable', 5)
        // Check a full page screenshot with options for `checkTabbablePage` command
        await expect(browser).toMatchTabbablePageSnapshot('check-tabbable', {
            /* some options */
        })
    })

    it('should save some screenshots', async () => {
        // Save a screen
        await browser.saveScreen('examplePage', {
            /* some options */
        })

        // Save an element
        await browser.saveElement(
            await $('#element-id'),
            'firstButtonElement',
            {
                /* some options */
            }
        )

        // Save a full page screenshot
        await browser.saveFullPageScreen('fullPage', {
            /* some options */
        })

        // Save a full page screenshot with all tab executions
        await browser.saveTabbablePage('save-tabbable', {
            /* some options, use the same options as for saveFullPageScreen */
        })
    })

    it('should compare successful with a baseline', async () => {
        // Check a screen
        await expect(
            await browser.checkScreen('examplePage', {
                /* some options */
            })
        ).toEqual(0)

        // Check an element
        await expect(
            await browser.checkElement(
                await $('#element-id'),
                'firstButtonElement',
                {
                    /* some options */
                }
            )
        ).toEqual(0)

        // Check a full page screenshot
        await expect(
            await browser.checkFullPageScreen('fullPage', {
                /* some options */
            })
        ).toEqual(0)

        // Check a full page screenshot with all tab executions
        await expect(
            await browser.checkTabbablePage('check-tabbable', {
                /* some options, use the same options as for checkFullPageScreen */
            })
        ).toEqual(0)
    })
})
IMPORTANT

This service provides save and check methods. If you run your tests for the first time you SHOULD NOT combine save and compare methods, the check-methods will automatically create a baseline image for you

#####################################################################################
 INFO:
 Autosaved the image to
 /Users/wswebcreation/sample/baselineFolder/desktop_chrome/examplePage-chrome-latest-1366x768.png
#####################################################################################

When you've disabled to automatically save baseline images, the Promise will be rejected with the following warning.

#####################################################################################
 Baseline image not found, save the actual image manually to the baseline.
 The image can be found here:
 /Users/wswebcreation/sample/.tmp/actual/desktop_chrome/examplePage-chrome-latest-1366x768.png
#####################################################################################

This means that the current screenshot is saved in the actual folder and you manually need to copy it to your baseline. If you instantiate @wdio/visual-service with autoSaveBaseline: true the image will automatically be saved into the baseline folder.

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