Assertions

Aug 24, 2021
13 minutes to read

Use Assertions to verify page action results. Assertions are comparisons that help you determine if the page state is correct. Assertions compare the actual value of a page-related variable to the value you expect it to have. If an assertion fails, the test fails too.

You cannot record assertions.

Test Scripts

The t.expect TestController method executes assertions like so:

await t.expect( actual ).eql( expected, message, options );

The TestCafe framework documentation includes an assertions guide.

Codeless Tests

The Assertions section of the Actions panel contains assertion templates.

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Greater than or Equals to

Less than

Less than or Equals to

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Assertion Parameters

Assertion Target

If the DOM tab is active, the assertion examines a page element that corresponds to an element selector;
If the fn tab is active, the assertion examines the return value of a client function.

Element Selector

Create a new Element Selector query in one of two ways:

Pick the target element with the element picker. TestCafe Studio generates a set of selectors for the target element. To view available selectors, click the button next to the Element Selector input field.

Note

The element picker is available only during recording.

Use the element selector creation dialog.

Select the property you want to include in the comparison from the Verified Property dropdown. See Element Properties for the list of available properties.

Client Function Return Value

Select a function to execute from the Function drop-down list. The Function drop-down menu contains functions that you defined earlier in the test.

Expected Value

Many assertions compare the results of their evaluations to the value of the Expected Value parameter. You can either manually set the parameter’s value, or click the button to populate the field with the current value of a page element parameter.

Note

Enclose strings in quotes: write “Thank you, Peter” instead of Thank you, Peter.

Automatic assertion evaluation (recording mode only)

When you add an assertion to your test during recording, TestCafe Studio immediately performs the calculations necessary to execute that assertion. This data may help you pick the right value for the expected value field.

If the assertion you added refers to a page element, TestCafe Studio evaluates the properties of that element, and displays them:

in the property grid;
in the Actual Value field next to the Verified Property field.

If the assertion you added refers to a client function, TestCafe Studio automatically evaluates the function in question, and populates the Actual Value field with the result.

Assertion Options

You can configure assertions with the following options:

Timeout - success time limit (in milliseconds). TestCafe repeats the assertion until either the assertion succeeds or the time runs out. TestCafe Studio evaluates the assertion target anew with each attempt.
Message - the message to output in case of test failure. To add this option, click the Add Message button in the assertion parameters area.

Assertion Status

TestCafe Studio displays an Assertion Status indicator when it executes an assertion in recording mode.

The Assertion Status indicator can display the following information:

- Success: the assertion passed;
- Failure: the assertion failed;
- Unknown: the assertion has not been executed;
- Ongoing: the assertion is in progress.

Click the Assertion Status indicator to execute the assertion again after you make changes.

Assertion Types

Deep Equal

Asserts that a verified value is equal to an expected value.

For example, the following assertion verifies if the number of label elements on a tested page is equal to 9:

Warning

The Deep Equal assertion takes into account whitespace characters like newline symbols or tabulations when it compares strings. Specify these characters in the Expected Value field (for instance, \n) or use the Contains and Match assertions to compare only visible symbols.

Not Deep Equal

Asserts that a verified value is not equal to an expected value.

For example, the following assertion checks if the number of label elements on a tested page is not equal to 10:

Ok

Asserts that a verified value is true. You can use this assertion to verify if the element exists, if it is visible, or if it is focused.

For example, the following assertion checks if the Submit button is visible:

Not Ok

Asserts that a verified value is false. You can use this assertion to check if the element does not exist, is not visible, or is not focused.

For example, the following assertion checks if the Submit button does not exist:

Contains

Asserts that a verified value contains an expected value.

For example, the following assertion checks if the input #developer-name contains the text Peter:

Not Contains

Asserts that a verified value does not contain an expected value.

For example, the following assertion checks if the input #developer-name does not contain the text John:

Type of

Asserts that a verified value (an element or its attribute) is the type specified in the Type Name field.

For example, the following assertion checks the type of the element’s value property:

Not Type of

Asserts that a verified value (an element or its attribute) is not the type specified in the Type Name field.

For example, the following assertion checks the type of the element’s visible property:

Greater than

Asserts that a verified value is greater than an expected value.

For example, the following assertion checks if the element’s ClientWidth property is greater than 700:

Greater than or Equal to

Asserts that a verified value is greater than or equal to an expected value.

For example, the following assertion checks if the element’s ClientWidth property is greater than or equals to 700:

Less than

Asserts that a verified value is less than the expected value.

For example, the following assertion checks if the element’s OffsetHeight property is less than 150:

Less than or Equal to

Asserts that a verified value is less than or equal to an expected value.

For example, the following assertion checks if the element’s OffsetHeight property is less than or equals to 150:

Within

Asserts that a verified value is within a range from Start Value to End Value. Bounds are inclusive.

For example, the following assertion checks if the element’s ScrollHeight property is within a range from 100 to 200:

Not Within

Asserts that a verified value is not within a range from Start Value to End Value. Bounds are inclusive.

For example, the following assertion checks if the element’s ScrollHeight property is within a range from 100 to 200:

Match

Asserts that a verified value matches a specified regular expression.

You can use the following options:

Global - Performs a global match.
Sticky - Performs a sticky search.
Multiline - Performs a multiline match.
Unicode - Unicode-related features are enabled.
Ignore Case - Performs a case-insensitive match.

For example, the following assertion checks if the input #developer-name contains the text Peter:

Important

When you specify a regular expression in JavaScript code, you should enclose a pattern in forward slashes:

However, in the Regular Expression parameter for the Match and Not Match assertions, you should not use forward slashes:

Not Match

Asserts that a verified value does not match a specified regular expression.

You can use the following options:

Global - Performs a global match.
Sticky - Performs a sticky search.
Multiline - Performs a multiline match.
Unicode - Unicode-related features are enabled.
Ignore Case - Performs a case-insensitive match.

For example, the following assertion checks if the input #developer-name does not contain the text John:

Important

When you specify a regular expression in JavaScript code, you enclose a pattern in forward slashes, as follows:

In the Regular Expression parameter for the Match or Not Match assertion, however, you should not use forward slashes:

Element Properties

When you verify a page element’s state, you create a selector that matches a target element and then select the element’s property from the property grid.

The property grid always contains the General Properties group. If you add an assertion during recording, the property grid can also contain the following groups: CSS Properties, Attributes, Rectangle.

Note

When you add an assertion during recording, the property grid also displays property values.

General Properties

Contains properties that are common across all elements and properties that are specific to the target element.

Property	Type	Description
`exists`	Boolean	`true` if at least one matching element exists.
`count`	Number	The number of matching elements.
`focused`	Boolean	`true` if the element is focused, meaning the document.activeElement property returns this element.
`visible`	Boolean	`true` if the element is visible, meaning the element does not have `display: none` or `visibility: hidden` CSS properties, and has a non-zero width and height.
`checked`	Boolean	For checkbox and radio input elements, their current state. For other elements, `undefined`.
`childElementCount`	Number	The number of child HTML elements.
`childNodeCount`	Number	The number of child nodes.
`classNames`	Array of String	The list of element classes.
`clientHeight`	Number	The inner height of the element, including padding but not the horizontal scrollbar height, border, or margin. See Element.clientHeight.
`clientLeft`	Number	The width of the left border of the element. See Element.clientLeft.
`clientTop`	Number	The width of the top border of the element. See Element.clientTop.
`clientWidth`	Number	The inner width of the element, including padding but not the vertical scrollbar width, border, or margin. See Element.clientWidth.
`hasChildElements`	Boolean	`true` if the element has child HTML elements.
`hasChildNodes`	Boolean	`true` if the element has child nodes.
`id`	String	The element’s identifier. See Element.id.
`innerText`	String	The element’s text content “as rendered”. See Element.innerText.
`namespaceURI`	String	The namespace URI of the element. If the element does not have a namespace, this property is set to `null`. See Element.namespaceURI.
`nodeType`	Number	The type of the node. See Node.nodeType.
`offsetHeight`	Number	The height of the element including vertical padding and borders. See HTMLElement.offsetHeight.
`offsetLeft`	Number	The number of pixels that the upper left corner of the element is offset by to the left within the `offsetParent` node. See HTMLElement.offsetLeft.
`offsetTop`	Number	The number of pixels that the upper left corner of the element is offset by to the top within the `offsetParent` node. See HTMLElement.offsetTop.
`offsetWidth`	Number	The width of the element including vertical padding and borders. See HTMLElement.offsetWidth.
`selected`	Boolean	For an `<option>` element, indicates if it is currently selected. For other elements, `undefined`. See HTMLOptionElement.
`selectedIndex`	Number	For a `<select>` element, the index of the first selected `<option>` element. For other elements, `undefined`. See HTMLSelectElement.selectedIndex.
`scrollHeight`	Number	The height of the element’s content, including content that is not visible on the screen due to overflow. See Element.scrollHeight.
`scrollLeft`	Number	The number of pixels that the element’s content is scrolled to the left. See Element.scrollLeft.
`scrollTop`	Number	The number of pixels that the element’s content is scrolled upward. See Element.scrollTop.
`scrollWidth`	Number	Either the width of the element’s content (in pixels) or the width of the element itself, whichever is greater. See Element.scrollWidth.
`tagName`	String	The element’s name. See Element.tagName.
`textContent`	String	The text content of the node and its descendants. See Node.textContent.
`value`	String	For input elements, the current value. For other elements, `undefined`.

CSS Properties

Contains the target element’s CSS properties and their computed values.

Attributes

Contains element attributes.

Rectangle

Contains the properties that specify the element’s size and its position relative to the viewport: bottom, height, left, right, top, width.

Examples

Check if an Element Exists

Use the Ok assertion to verify the element’s exists property.

For example, the following assertion checks if the Submit button exists:

Check if an Element is Visible or Focused

Use the Ok assertion to verify the element’s visible or focused property.

Check The Number of Elements

To check the number of elements, use the Deep Equal assertion to verify the count property.

For example, the following assertion checks the number of label elements on the page:

You can also check the number of elements in more complex scenarios, for example, when you perform search queries or test table filtering. In these cases, you can use assertions like Greater than, Less than, Within, and so on.

The following assertion verifies if the number of table rows is between 3 and 5:

Check an Element’s Text

Use the Contains or Match assertions to check an element’s text.

For example, to check the text in an <input> or <textarea>, verify the element’s value property:

For other elements, you can verify the innerText or textContent property. For example, the following assertion verifies the article header’s text:

Check an Element’s Attribute Value

You can use the Deep Equal, Ok or other assertions to check an element’s attribute value.

To access the element’s attributes, add an assertion during test recording. The attributes are displayed in the property grid’s Attributes category.

For example, the following assertion checks the button’s type attribute:

Check the Page URL

To check the page URL, define a function that returns the location.href value and verify this value with a Deep Equal assertion.

Page URL: https://devexpress.github.io/testcafe/example/

View Code

getUrl

return window.location.href;

Expected Value: 'https://devexpress.github.io/testcafe/example/'

Check the User Agent

You can obtain the navigator.userAgent string with a function and use the Deep Equal assertion to verify the value.

View Code

getUserAgent

return window.navigator.userAgent;

Expected Value: 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.0.2 Safari/605.1.15'

Verify a Complex Object

Client-side functions allow you to perform complex verifications. This example shows how to verify data from specific table columns.

The tested page contains a Data Grid control. To verify the content in its columns, create a function that obtains data from these columns and pushes these data to an array. The Deep Equal assertion can check this array against the expected data.

Page URL: https://js.devexpress.com

View Code

getSalesAmount

const grid = document.querySelector('.dx-datagrid-rowsview');
const rowCount = grid.querySelectorAll('.dx-data-row').length;
const sales = grid.querySelectorAll('td:nth-child(3)');
const customers = grid.querySelectorAll('td:nth-child(7)');

const array = [];

for (let i = 0; i < rowCount; i++) {
    array.push({
        sales: sales[i].textContent,
        customer: customers[i].textContent
    });
}

return array;

Expected Value

[
    { sales: '$6,370', customer: 'Renewable Supplies' },
    { sales: '$4,530', customer: 'Apollo Inc' },
    { sales: '$1,110', customer: 'Johnson & Assoc' },
    { sales: '$6,600', customer: 'Global Services' },
    { sales: '$2,830', customer: 'Health Plus Inc' },
    { sales: '$6,770', customer: 'Gemini Stores' },
    { sales: '$1,460', customer: 'Discovery Systems' }
]