Maximize and minimize window in Selenium Python - Deep Dive

Overview - Maximize and minimize window

What is it?

Maximizing and minimizing a window means changing the size of the browser window during automated tests. Maximizing makes the window fill the entire screen, while minimizing hides it or reduces it to the taskbar. This helps test how web pages behave in different window sizes and states.

Why it matters

Without controlling window size, tests might run in unexpected window states causing inconsistent results. For example, some page elements may appear or disappear depending on window size. Maximizing ensures the page is fully visible, while minimizing can simulate background running or test resource usage.

Where it fits

Before learning this, you should know how to set up Selenium WebDriver and open a browser window. After mastering window control, you can learn about responsive testing, handling multiple windows or tabs, and advanced browser interactions.

Mental Model

Core Idea

Maximizing and minimizing windows lets automated tests control browser size and visibility to simulate real user environments.

Think of it like...

It's like adjusting the blinds on a window at home: you can open them fully to let in all the light (maximize) or close them to block the view (minimize).

┌─────────────────────────────┐
│        Browser Window       │
│ ┌───────────────────────┐ │
│ │ Maximized: fills screen│ │
│ └───────────────────────┘ │
│ ┌─────────────────────────┐ │
│ │ Minimized: hidden/taskbar│
│ └─────────────────────────┘ │
└─────────────────────────────┘

Build-Up - 7 Steps

1

Foundation

Opening a browser window

Concept: Learn how to start a browser session using Selenium WebDriver.

from selenium import webdriver # Create a new Chrome browser instance driver = webdriver.Chrome() # Open a webpage driver.get('https://example.com')

Result

A new browser window opens and loads the example.com webpage.

Understanding how to open a browser is the first step before controlling its size or state.

2

Foundation

Getting current window size

Concept: Learn how to check the current size of the browser window.

size = driver.get_window_size() print(f"Width: {size['width']}, Height: {size['height']}")

Result

Prints the current width and height of the browser window in pixels.

Knowing the current window size helps verify changes after maximizing or minimizing.

3

Intermediate

Maximizing the browser window

🤔Before reading on: do you think maximizing changes the window size instantly or gradually? Commit to your answer.

Concept: Learn how to make the browser window fill the entire screen.

driver.maximize_window()

Result

The browser window expands to fill the full screen immediately.

Maximizing ensures all page elements are visible, preventing layout issues caused by small windows.

4

Intermediate

Minimizing the browser window

🤔Before reading on: do you think minimizing closes the browser or just hides it? Commit to your answer.

Concept: Learn how to hide or reduce the browser window to the taskbar.

driver.minimize_window()

Result

The browser window is hidden or reduced to the taskbar but remains open.

Minimizing simulates the browser running in the background without closing it, useful for resource or multitasking tests.

5

Intermediate

Restoring window to original size

Concept: Learn how to set the window back to a specific size after maximizing or minimizing.

driver.set_window_size(1024, 768)

Result

The browser window resizes to 1024 pixels wide and 768 pixels tall.

Controlling window size precisely allows testing responsive designs and different screen resolutions.

6

Advanced

Combining window states in tests

🤔Before reading on: do you think switching between maximize and minimize affects page state? Commit to your answer.

Concept: Learn how to switch window states during a test to simulate user behavior.

driver.maximize_window() # Perform some checks driver.minimize_window() # Simulate background running driver.set_window_size(800, 600) # Test responsive layout

Result

The browser window changes states as commanded, allowing tests to verify page behavior in each state.

Switching window states during tests helps catch bugs that only appear when users resize or hide the browser.

7

Expert

Limitations and platform differences

🤔Before reading on: do you think maximize and minimize behave identically on all operating systems? Commit to your answer.

Concept: Understand how different OS and browsers may handle maximize and minimize differently.

Note: On some Linux systems, minimize_window() may not work as expected due to window manager differences. Similarly, maximize_window() might not fill the screen if OS restricts window size. Tests should handle these cases gracefully.

Result

Tests that rely on window state control may behave differently on various platforms, requiring conditional handling.

Knowing platform-specific behavior prevents flaky tests and helps design robust cross-platform test suites.

Under the Hood

Selenium WebDriver sends commands to the browser's driver (like chromedriver) which then instructs the browser to change its window state. The browser interacts with the operating system's window manager to maximize or minimize the window. These commands are asynchronous and depend on OS support.

Why designed this way?

This design separates test code from browser internals, allowing Selenium to control many browsers uniformly. Using OS window managers ensures the window behaves like a real user action, improving test realism.

┌───────────────┐
│ Selenium Test │
└──────┬────────┘
       │ send command
┌──────▼────────┐
│ WebDriver API │
└──────┬────────┘
       │ translate
┌──────▼────────┐
│ Browser Driver│
└──────┬────────┘
       │ OS window command
┌──────▼────────┐
│ OS Window Mgr │
└───────────────┘

Myth Busters - 4 Common Misconceptions

Quick: Does minimize_window() close the browser? Commit to yes or no.

Common Belief: Minimizing the window closes the browser session.

Reality: Minimizing only hides or reduces the window; the browser remains open and active.

Why it matters: Closing the browser unexpectedly would end the test session, causing failures and lost data.

Quick: Does maximize_window() always fill the entire screen on all OS? Commit to yes or no.

Common Belief: Maximizing always makes the window fill the entire screen exactly the same way everywhere.

Reality: Maximize behavior depends on OS and window manager; sometimes it leaves space for taskbars or docks.

Why it matters: Assuming exact full-screen size can cause tests to fail when elements are partially hidden or layouts differ.

Quick: Does setting window size override maximize state? Commit to yes or no.

Common Belief: Once maximized, setting window size has no effect until the window is restored.

Reality: Setting window size changes the window size immediately, even if previously maximized.

Why it matters: Misunderstanding this can cause confusion when tests behave unexpectedly after resizing.

Quick: Does minimizing the window pause JavaScript execution? Commit to yes or no.

Common Belief: Minimizing the browser pauses all scripts and page activity.

Reality: Scripts continue running in the background unless the browser or OS suspends them explicitly.

Why it matters: Tests relying on script pauses during minimize may produce inconsistent results.

Expert Zone

1

Maximize and minimize commands are asynchronous; tests should wait for the window state to settle before proceeding.

2

Some browsers or OS combinations may not support minimize_window(), requiring fallback strategies like moving the window off-screen.

3

Using maximize_window() can affect browser zoom or DPI scaling, which impacts element positioning and test accuracy.

When NOT to use

Avoid relying solely on maximize or minimize for responsive testing; instead, use set_window_size() to test specific screen sizes. For headless browsers, maximize and minimize may have no effect; use viewport size settings instead.

Production Patterns

In real-world tests, maximize_window() is often used at test start to ensure consistent layout. Minimize_window() is rarely used but can simulate background running or multitasking. Tests combine set_window_size() with maximize to cover multiple device resolutions.

Connections

Responsive Web Design Testing

Builds-on

Controlling window size and state is essential to test how web pages adapt to different screen sizes and orientations.

Operating System Window Management

Underlying system

Understanding OS window managers helps explain why maximize and minimize behave differently across platforms.

Human Attention and Multitasking Psychology

Analogous behavior

Minimizing a window simulates how users switch attention between tasks, which affects how web apps should handle background activity.

Common Pitfalls

#1 Assuming minimize_window() closes the browser.

Wrong approach:

driver.minimize_window()
driver.find_element_by_id('submit').click() # Fails because window is hidden

Correct approach:

driver.minimize_window()
# Wait or switch context if needed
# Then interact or restore window before clicking

Root cause:

Misunderstanding that minimize hides but does not close the browser, so elements may not be interactable immediately.

#2 Not waiting after maximize_window() before interacting.

Wrong approach:

driver.maximize_window()
driver.find_element_by_id('menu').click() # Sometimes fails due to timing

Correct approach:

driver.maximize_window()
time.sleep(1) # Wait for window to resize
driver.find_element_by_id('menu').click()

Root cause:

Ignoring that window resizing is asynchronous and needs time to complete before actions.

#3 Using maximize_window() in headless mode expecting visual change.

Wrong approach:

options = webdriver.ChromeOptions()
options.add_argument('--headless')
driver = webdriver.Chrome(options=options)
driver.maximize_window()

Correct approach:

options = webdriver.ChromeOptions()
options.add_argument('--headless')
driver = webdriver.Chrome(options=options)
driver.set_window_size(1920, 1080)

Root cause:

Headless browsers do not support window state changes visually; viewport size must be set explicitly.

Key Takeaways

Maximizing and minimizing browser windows lets tests simulate real user environments by controlling window size and visibility.

Maximize fills the screen, minimize hides the window but keeps the browser running; both affect how pages render and behave.

Window state commands depend on the operating system and browser, so tests must handle platform differences carefully.

Waiting for window state changes to complete avoids flaky tests caused by timing issues.

For precise control, setting window size is often better than relying solely on maximize or minimize.