Custom annotations in Selenium Java - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a custom annotation in Java testing?

A custom annotation is a user-defined marker or metadata that you create to add extra information to your test code, which can be processed at runtime or compile time to influence test behavior.

beginner

How do you define a custom annotation in Java?

You define a custom annotation using the @interface keyword, specify retention policy (like RUNTIME), and optionally target elements (like METHOD or FIELD).

intermediate

Why use custom annotations in Selenium tests?

Custom annotations help organize tests, add metadata like test priority or author, and enable reusable logic such as custom waits or setup steps, making tests cleaner and easier to maintain.

intermediate

What is the RetentionPolicy.RUNTIME in custom annotations?

RetentionPolicy.RUNTIME means the annotation is available during runtime via reflection, allowing test frameworks to read and act on the annotation while tests run.

beginner

Give an example of a simple custom annotation for marking tests as 'Critical'.

Example:

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

@Retention(RetentionPolicy.RUNTIME)
public @interface CriticalTest {
  String value() default "";
}

This annotation can be placed on test methods to mark them as critical.

Which keyword is used to create a custom annotation in Java?

A @interface

B @annotation

C interface

D @custom

The @interface keyword is used to define a custom annotation in Java.

What does RetentionPolicy.RUNTIME mean for a custom annotation?

A Annotation is available only in source code

B Annotation is available at runtime via reflection

C Annotation is discarded after compilation

D Annotation is only for documentation

RetentionPolicy.RUNTIME means the annotation is kept in the compiled class and can be accessed during runtime.

Why might you use custom annotations in Selenium tests?

A To add metadata and control test execution

B To replace WebDriver entirely

C To write CSS selectors

D To compile Java code faster

Custom annotations add metadata like priority or author and help control test execution flow.

Which Java package is commonly used to access annotations at runtime?

A java.util.stream

B java.io

C java.lang.reflect

D java.net

The java.lang.reflect package provides classes to inspect annotations at runtime.

What element type would you specify to apply a custom annotation only to methods?

A ElementType.FIELD

B ElementType.TYPE

C ElementType.PARAMETER

D ElementType.METHOD

ElementType.METHOD restricts the annotation usage to methods only.

Explain how to create and use a custom annotation in Selenium Java tests.

Think about how annotations add metadata and how Selenium tests can read them.

Describe the benefits of using custom annotations in test automation.

Consider how annotations help manage many tests in a project.

Practice

1. What is the main purpose of creating custom annotations in Selenium Java tests?

easy

A. To automatically generate test reports without any code

B. To replace all Selenium WebDriver methods with custom ones

C. To write test cases without using any Java code

D. To add metadata that can control test behavior or provide extra information

Solution

1. Step 1: Understand what annotations do

   Annotations add metadata to code elements like methods or classes, influencing how tests run or are processed.

2. Step 2: Identify the role of custom annotations

   Custom annotations let testers add their own metadata to control or describe tests beyond built-in annotations.

3. Final Answer:

   To add metadata that can control test behavior or provide extra information -> Option D

4. Quick Check:

   Custom annotations = metadata control [OK]

Hint: Custom annotations add info to tests, not replace code [OK]

Common Mistakes:

• Thinking custom annotations replace WebDriver methods
• Assuming they auto-generate reports without code
• Believing tests can run without Java code

2. Which of the following is the correct syntax to define a custom annotation named TestInfo in Java?

easy

A. public @interface TestInfo { String author(); int priority() default 1; }

B. public class TestInfo { String author(); int priority() default 1; }

C. @interface TestInfo { public String author; public int priority = 1; }

D. annotation TestInfo { String author(); int priority(); }

Solution

1. Step 1: Recall Java annotation syntax

   Annotations use the keyword @interface and define methods without bodies for elements.

2. Step 2: Check public @interface TestInfo { String author(); int priority() default 1; } syntax

   public @interface TestInfo { String author(); int priority() default 1; } correctly uses public @interface TestInfo and defines methods with optional default values.

3. Final Answer:

   public @interface TestInfo { String author(); int priority() default 1; } -> Option A

4. Quick Check:

   Annotation syntax = @interface + methods [OK]

Hint: Annotations use @interface keyword, not class or annotation [OK]

Common Mistakes:

• Using class instead of @interface
• Declaring fields instead of methods inside annotation
• Missing default keyword for optional elements

3. Given the custom annotation and usage below, what will be the output when printTestInfo() is called?

import java.lang.reflect.Method;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

@Retention(RetentionPolicy.RUNTIME)
@interface TestInfo {
  String author();
  int priority() default 1;
}

public class SampleTest {
  @TestInfo(author = "Alice", priority = 3)
  public void testMethod() {}

  public static void printTestInfo() throws Exception {
    Method m = SampleTest.class.getMethod("testMethod");
    TestInfo info = m.getAnnotation(TestInfo.class);
    System.out.println(info.author() + ":" + info.priority());
  }
}

medium

A. Compilation error

B. Alice:1

C. Alice:3

D. null:0

Solution

1. Step 1: Understand annotation retrieval via reflection

   The method getAnnotation(TestInfo.class) fetches the annotation instance on testMethod.

2. Step 2: Check annotation values

   The annotation has author="Alice" and priority=3, so printing them outputs "Alice:3".

3. Final Answer:

   Alice:3 -> Option C

4. Quick Check:

   Reflection reads annotation values correctly [OK]

Hint: Annotation values print as set, defaults overridden [OK]

Common Mistakes:

• Assuming default priority is used instead of 3
• Expecting null because of missing retention policy
• Thinking reflection causes compile error

4. Consider this custom annotation definition:

@interface TestInfo {
  String author();
  int priority() default 1;
}

And this usage:

@TestInfo(author = "Bob")
public void test() {}

Why might the following code throw a NullPointerException when accessing priority()?

TestInfo info = testMethod.getAnnotation(TestInfo.class);
int p = info.priority();

medium

A. The priority method is missing in the annotation definition

B. The annotation is not retained at runtime, so info is null

C. The author value is missing, causing priority to be null

D. Annotations cannot have default values

Solution

1. Step 1: Check annotation retention policy

   If the annotation lacks @Retention(RetentionPolicy.RUNTIME), it is not available at runtime, so getAnnotation returns null.

2. Step 2: Understand NullPointerException cause

   Since info is null, calling info.priority() throws NullPointerException.

3. Final Answer:

   The annotation is not retained at runtime, so info is null -> Option B

4. Quick Check:

   Missing runtime retention = null annotation [OK]

Hint: Always add @Retention(RetentionPolicy.RUNTIME) for runtime use [OK]

Common Mistakes:

• Assuming default values cause null
• Thinking missing author causes error
• Believing annotations can't have defaults

5. You want to create a custom annotation @StepInfo to mark test steps with a description and an optional severity level (default "LOW"). You also want to process these annotations at runtime to print all step descriptions with their severity. Which combination of annotation elements and retention policy is correct to achieve this?

hard

A. @Retention(RetentionPolicy.RUNTIME) public @interface StepInfo { String description(); String severity() default "LOW"; }

B. @Retention(RetentionPolicy.CLASS) public @interface StepInfo { String description(); String severity() default "LOW"; }

C. @Retention(RetentionPolicy.SOURCE) public @interface StepInfo { String description(); String severity(); }

D. public @interface StepInfo { String description(); String severity() default "LOW"; }

Solution

1. Step 1: Choose correct retention for runtime processing

   To access annotations at runtime via reflection, use @Retention(RetentionPolicy.RUNTIME).

2. Step 2: Define annotation elements with default values

   Define description() as required and severity() with default "LOW" for optional use.

3. Final Answer:

   @Retention(RetentionPolicy.RUNTIME) public @interface StepInfo { String description(); String severity() default "LOW"; } -> Option A

4. Quick Check:

   Runtime retention + default value = correct annotation [OK]

Hint: Use RUNTIME retention to read annotations during tests [OK]

Common Mistakes:

• Using CLASS or SOURCE retention prevents runtime access
• Omitting retention causes default CLASS retention
• Not providing default for optional elements