Welcome to an exciting part of our course where we delve into automating dropdown selections using Playwright. Dropdowns are common on web pages for user selections, such as choosing a category of books or filtering search results. This lesson will guide you through writing automated tests to interact with dropdowns, enhancing your Playwright skills.

In this lesson, you will learn how to automate dropdown selection with Playwright. We'll cover the process of identifying and interacting with dropdown elements on a webpage to select a specific option. Here's a sneak peek:

In this test, we perform the following actions:

1. Navigate to a Web Page: Using page.goto('http://localhost:3000/books'), Playwright opens the specified URL, which hosts the dropdown we want to manipulate.

2. Select an Option from a Dropdown: We use page.selectOption('select#categories', 'Fantasy') to automate the action of selecting the 'Fantasy' option. The CSS selector select#categories is used to fetch the 'select' element with an id of 'categories', which corresponds to an HTML element like <select id="categories"…>. This simulates the user action of choosing an option from the dropdown.

3. Verify the Selected Value: By evaluating the current value of the dropdown with page.$eval('select#categories', select => select.value), we ensure it's set to 'Fantasy'. This serves as a check to confirm that the selection occurred as expected.

   • The page.$eval method fetches the element matching the CSS selector 'select#categories', which is the dropdown element.

In addition to selecting a specific option, it can be beneficial to understand how to retrieve all possible options from a dropdown. This assists in scenarios where you need to verify the presence of certain options or dynamically interact with them.

In this example, we perform the following actions:

1. Navigate to a Web Page: Just like selecting an option, we first navigate to the desired page using page.goto('http://localhost:3000/books').

2. Understand Arrays: Arrays are used to store multiple items in a single variable and are defined using square brackets []. In the code, the array expectedOptions is initialized as const expectedOptions = ['', 'Literature', 'Science Fiction', 'Fantasy'];, containing the list of expected dropdown values. This list will be then used to compare and verify the list of options that we get from the page.

3. Retrieve All Options: We use page.$$eval('select#categories option', options => options.map(option => option.value)) to fetch all option elements within the dropdown. The CSS selector select#categories option targets each option under the dropdown. This returns an array of option values.

   • Notice that we use $$eval here instead of $eval: is used to select a single element and execute a function on it, while is used to select all matching elements and apply a function to an array of those elements.

Arrow functions in JavaScript allow you to describe a task or behavior in a clear and straightforward way using the => symbol.

Here's how they work:

1. Parameters: These are like placeholders. When you write an arrow function, you may use parentheses () to list what the function needs to perform its task. For example, if you want to add two numbers, you'll have parameters for those numbers:

   Here, a and b are parameters.

2. Task: After the parameters, an arrow function shows what it does using the => symbol. In the example above, a + b is the task of adding the two numbers.

In our Playwright examples, let's see arrow functions in action:

• In page.$eval('select#categories', select => select.value), select => select.value is an arrow function. Here, select acts as a placeholder for the dropdown element, and select.value describes the task of getting the dropdown's value.

• In page.$$eval('select#categories option', options => options.map(option => option.value)), options.map(option => option.value) uses placeholders to represent each dropdown option, describing how to get each option's value.

Automating dropdown selections is crucial for creating robust automated tests. It ensures that web applications function correctly across a variety of user interactions, leading to improved user experiences and saving time in manual testing. Mastery of this skill will boost your efficiency in writing tests and handling dynamic web environments.

With this newfound knowledge, you're all set to move into the practice section. Let's put these concepts into action and deepen your understanding!