Custom ExpectedCondition in Selenium Java - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Custom ExpectedCondition in Selenium?

A Custom ExpectedCondition is a user-defined condition that Selenium waits for before proceeding. It helps handle specific scenarios not covered by built-in conditions.

intermediate

How do you create a Custom ExpectedCondition in Selenium Java?

You create a Custom ExpectedCondition by implementing the ExpectedCondition<T> interface and overriding the apply method with your condition logic.

beginner

Why use Custom ExpectedConditions instead of Thread.sleep()?

Custom ExpectedConditions wait only as long as needed for a condition, making tests faster and more reliable than fixed waits like Thread.sleep().

intermediate

Example: What does this Custom ExpectedCondition do?

ExpectedCondition<Boolean> elementHasText = driver -> {
  WebElement el = driver.findElement(By.id("message"));
  return el.getText().contains("Success");
};

This condition waits until the element with id 'message' contains the text 'Success'. It returns true when the text is found, otherwise false.

beginner

What method do you use to apply a Custom ExpectedCondition in Selenium?

Use WebDriverWait's until() method, passing your Custom ExpectedCondition to wait until it returns true or a value.

What interface must you implement to create a Custom ExpectedCondition in Selenium Java?

A By

B WebDriverWait

C WebElement

D ExpectedCondition<T>

Custom ExpectedConditions require implementing the ExpectedCondition interface.

Which method do you override when creating a Custom ExpectedCondition?

A findElement

B wait

C apply

D click

The apply method contains the logic to check the condition.

Why is using Custom ExpectedConditions better than Thread.sleep()?

A They wait only as long as needed

B They are slower

C They ignore conditions

D They always wait the maximum time

Custom ExpectedConditions wait dynamically, improving test speed and reliability.

What does WebDriverWait.until() do with a Custom ExpectedCondition?

A Waits until the condition returns true or a value

B Immediately fails the test

C Ignores the condition

D Clicks on the element

until() waits for the condition to be met or timeout.

Which of these is a valid use case for a Custom ExpectedCondition?

A Hard coding a fixed wait time

B Waiting for an element's text to contain specific words

C Ignoring element visibility

D Skipping waits entirely

Custom ExpectedConditions are useful for waiting on specific element states like text content.

Explain how to create and use a Custom ExpectedCondition in Selenium Java.

Think about the interface and method you need to write, then how to wait for it.

Why should you prefer Custom ExpectedConditions over fixed waits like Thread.sleep() in test automation?

Consider how waiting smarter helps tests run better.

Practice

1. What is the main purpose of creating a Custom ExpectedCondition in Selenium Java?

easy

A. To automatically generate test reports

B. To replace the WebDriverWait class entirely

C. To speed up test execution by skipping waits

D. To define a specific condition that WebDriverWait will wait for before proceeding

Solution

1. Step 1: Understand the role of ExpectedCondition

   ExpectedCondition defines a condition that WebDriverWait checks repeatedly until it returns a non-null value or true.

2. Step 2: Purpose of Custom ExpectedCondition

   Creating a custom one allows you to specify your own logic for waiting, beyond built-in conditions.

3. Final Answer:

   To define a specific condition that WebDriverWait will wait for before proceeding -> Option D

4. Quick Check:

   Custom ExpectedCondition = Custom wait logic [OK]

Hint: Custom ExpectedCondition defines what to wait for [OK]

Common Mistakes:

• Thinking it replaces WebDriverWait
• Assuming it speeds up tests by skipping waits
• Confusing it with reporting features

2. Which method must be implemented when creating a custom ExpectedCondition in Selenium Java?

easy

A. apply(WebDriver driver)

B. waitForCondition()

C. checkCondition(WebElement element)

D. execute()

Solution

1. Step 1: Recall ExpectedCondition interface

   The ExpectedCondition interface requires implementing the apply method that takes a WebDriver and returns a result or null.

2. Step 2: Identify correct method name

   Only apply(WebDriver driver) is the correct method signature for custom conditions.

3. Final Answer:

   apply(WebDriver driver) -> Option A

4. Quick Check:

   Custom ExpectedCondition method = apply() [OK]

Hint: Custom ExpectedCondition always implements apply(driver) [OK]

Common Mistakes:

• Using wrong method names like waitForCondition or execute
• Confusing with WebElement methods
• Missing the WebDriver parameter

3. Given the following custom ExpectedCondition code snippet, what will be the output if the element with id 'status' has text 'Ready'?

ExpectedCondition<Boolean> condition = driver -> {
  WebElement el = driver.findElement(By.id("status"));
  return el.getText().equals("Ready") ? true : null;
};
WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(5));
boolean result = wait.until(condition);

medium

A. The code will cause a compilation error

B. The wait will pass and result will be true

C. The wait will pass and result will be null

D. The wait will timeout and throw TimeoutException

Solution

1. Step 1: Analyze the condition logic

   The condition returns true if the element's text equals "Ready", otherwise null.

2. Step 2: Understand WebDriverWait behavior

   WebDriverWait waits until the condition returns a non-null, true value. Since text is "Ready", condition returns true immediately.

3. Final Answer:

   The wait will pass and result will be true -> Option B

4. Quick Check:

   Condition true means wait passes [OK]

Hint: If condition returns true, wait.until returns true [OK]

Common Mistakes:

• Thinking null return means pass
• Assuming wait throws error on true
• Confusing null with false

4. Identify the error in this custom ExpectedCondition implementation:

ExpectedCondition<Boolean> condition = driver -> {
  WebElement el = driver.findElement(By.id("submit"));
  if(el.isDisplayed()) {
    return true;
  } else {
    return false;
  }
};

medium

A. findElement should be replaced with findElements

B. Using lambda expression is not allowed for ExpectedCondition

C. Returning false instead of null causes wait.until to stop waiting prematurely

D. Missing try-catch block for NoSuchElementException

Solution

1. Step 1: Understand ExpectedCondition return rules

   ExpectedCondition should return null to continue waiting, true to stop waiting successfully.

2. Step 2: Analyze the code's return values

   Returning false causes wait.until to stop waiting and throw TimeoutException immediately, which is not desired.

3. Final Answer:

   Returning false instead of null causes wait.until to stop waiting prematurely -> Option C

4. Quick Check:

   Return null to keep waiting, not false [OK]

Hint: Return null to wait longer, not false [OK]

Common Mistakes:

• Returning false instead of null to continue wait
• Assuming lambda is invalid
• Ignoring exception handling

5. You want to create a custom ExpectedCondition that waits until a list of elements with class 'item' contains at least 3 visible elements. Which implementation correctly achieves this?

hard

A. ExpectedCondition<Boolean> condition = driver -> {
List<WebElement> items = driver.findElements(By.className("item"));
long visibleCount = items.stream().filter(WebElement::isDisplayed).count();
return visibleCount >= 3 ? true : null;
};

B. ExpectedCondition<Boolean> condition = driver -> {
List<WebElement> items = driver.findElements(By.className("item"));
int count = 0;
for(WebElement item : items) {
if(item.isDisplayed()) count++;
}
return count > 3 ? true : false;
};

C. ExpectedCondition<Boolean> condition = driver -> {
List<WebElement> items = driver.findElements(By.className("item"));
return items.size() >= 3;
};

D. ExpectedCondition<Boolean> condition = driver -> {
List<WebElement> items = driver.findElements(By.className("item"));
return items.stream().allMatch(WebElement::isDisplayed);
};

Solution

1. Step 1: Understand the requirement

   Wait until at least 3 elements with class 'item' are visible (isDisplayed() true).

2. Step 2: Analyze each option

   ExpectedCondition<Boolean> condition = driver -> { List<WebElement> items = driver.findElements(By.className("item")); long visibleCount = items.stream().filter(WebElement::isDisplayed).count(); return visibleCount >= 3 ? true : null; }; counts visible elements and returns true if count >= 3, else null to keep waiting. This matches requirement and wait logic.
   ExpectedCondition<Boolean> condition = driver -> { List<WebElement> items = driver.findElements(By.className("item")); int count = 0; for(WebElement item : items) { if(item.isDisplayed()) count++; } return count > 3 ? true : false; }; returns false if count is not > 3, which stops wait prematurely.
   ExpectedCondition<Boolean> condition = driver -> { List<WebElement> items = driver.findElements(By.className("item")); return items.size() >= 3; }; checks total size, ignoring visibility.
   ExpectedCondition<Boolean> condition = driver -> { List<WebElement> items = driver.findElements(By.className("item")); return items.stream().allMatch(WebElement::isDisplayed); }; waits until all are visible, not at least 3.

3. Final Answer:

   Option A correctly waits for at least 3 visible elements -> Option A

4. Quick Check:

   Return true if condition met, else null to wait [OK]

Hint: Return true if condition met, else null to wait [OK]

Common Mistakes:

• Returning false instead of null to continue wait
• Ignoring visibility check
• Checking all elements visible instead of at least 3