Custom annotations in Selenium Java

Introduction

Custom annotations help you add extra information to your test code in a clear and reusable way.

You want to mark tests with special tags like @Smoke or @Regression to group them.

You need to add metadata to tests, like author name or test priority.

You want to create your own rules that can be checked before or after tests run.

You want to reduce repeated code by using annotations to configure tests.

Syntax

Selenium Java

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

@Retention(RetentionPolicy.RUNTIME)
public @interface YourAnnotation {
    String value() default "";
    int priority() default 1;
}

Use @Retention(RetentionPolicy.RUNTIME) to keep the annotation available during test execution.

Define annotation elements like methods with default values for flexibility.

Examples

This annotation stores author and category info for tests.

Selenium Java

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

@Retention(RetentionPolicy.RUNTIME)
public @interface TestInfo {
    String author();
    String category() default "General";
}

Use the custom annotation on a test method to add metadata.

Selenium Java

@TestInfo(author = "Alice", category = "Smoke")
public void testLogin() {
    // test code
}

Read annotation values at runtime using reflection.

Selenium Java

import java.lang.reflect.Method;

Method method = MyTestClass.class.getMethod("testLogin");
TestInfo info = method.getAnnotation(TestInfo.class);
System.out.println("Author: " + info.author());

Sample Program

This program defines a custom annotation @TestInfo with author and category. It applies it to a test method and reads the annotation values using reflection before running the test.

Selenium Java

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

@Retention(RetentionPolicy.RUNTIME)
@interface TestInfo {
    String author();
    String category() default "General";
}

public class CustomAnnotationExample {

    @TestInfo(author = "Bob", category = "Regression")
    public void testSearch() {
        System.out.println("Running testSearch");
    }

    public static void main(String[] args) throws Exception {
        Method method = CustomAnnotationExample.class.getMethod("testSearch");
        TestInfo info = method.getAnnotation(TestInfo.class);
        System.out.println("Author: " + info.author());
        System.out.println("Category: " + info.category());

        CustomAnnotationExample example = new CustomAnnotationExample();
        example.testSearch();
    }
}

Important Notes

Custom annotations must be retained at runtime to be accessible during test execution.

Use reflection carefully; it can slow down tests if overused.

Annotations help keep test code clean and organized by separating metadata from logic.

Summary

Custom annotations add reusable metadata to your tests.

They are defined with @interface and retained at runtime.

You can read annotation data using Java reflection to control test behavior.

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