Test profiles and configuration in Spring Boot - Mini Project: Build & Apply

Test profiles and configuration

📖 Scenario: You are building a Spring Boot application that needs to behave differently in testing and production environments. You want to use Spring profiles to separate configuration for tests and for normal running.

🎯 Goal: Create a Spring Boot application with two profiles: test and default. Configure a property app.message differently for each profile. Write a simple test that uses the test profile and checks the message.

📋 What You'll Learn

Create an application property app.message with value Production Message in the default profile

Create a test profile property app.message with value Test Message

Write a Spring Boot test class that activates the test profile

Write a test method that asserts the app.message property value is Test Message

💡 Why This Matters

🌍 Real World

Many applications need different settings for testing, development, and production. Spring profiles help manage these differences cleanly.

💼 Career

Understanding Spring profiles and configuration is essential for backend developers working with Spring Boot to write maintainable and testable applications.

1

Create default application properties

Create a file named src/main/resources/application.properties and add the line app.message=Production Message to set the default message.

Spring Boot

# Create src/main/resources/application.properties with app.message=Production Message
# Your code here

Hint

This file sets the default configuration for your Spring Boot app.

2

Create test profile properties

Create a file named src/test/resources/application-test.properties and add the line app.message=Test Message to set the message for the test profile.

Spring Boot

app.message=Production Message
# Create src/test/resources/application-test.properties with app.message=Test Message
# Your code here

Hint

This file overrides properties when the test profile is active.

3

Write a Spring Boot test class with test profile

Create a test class named MessageServiceTest in package com.example.demo. Annotate it with @SpringBootTest and @ActiveProfiles("test"). Inject Environment and write a test method testAppMessage() that asserts environment.getProperty("app.message") equals Test Message.

Spring Boot

app.message=Production Message

# In src/test/resources/application-test.properties
app.message=Test Message

// Create MessageServiceTest.java with @SpringBootTest and @ActiveProfiles("test")
// Inject Environment and write testAppMessage() to assert app.message equals "Test Message"
// Your code here

Hint

Use @ActiveProfiles("test") to activate the test profile during this test.

4

Add main application class

Create a main Spring Boot application class named DemoApplication in package com.example.demo with @SpringBootApplication annotation and a main method that runs SpringApplication.run(DemoApplication.class, args).

Spring Boot

app.message=Production Message

# In src/test/resources/application-test.properties
app.message=Test Message

package com.example.demo;

// Create DemoApplication.java with @SpringBootApplication and main method
// Your code here

Hint

This is the entry point of your Spring Boot application.

Practice

1. What is the main purpose of using test profiles in a Spring Boot application?

easy

A. To run the application with special settings only during testing

B. To improve the application's runtime performance in production

C. To automatically generate test data for the application

D. To disable security features permanently

Solution

1. Step 1: Understand test profiles concept

   Test profiles allow running the app with different settings specifically for testing purposes.

2. Step 2: Compare options

   Only To run the application with special settings only during testing correctly describes the purpose of test profiles as special settings for tests.

3. Final Answer:

   To run the application with special settings only during testing -> Option A

4. Quick Check:

   Test profiles = special test settings [OK]

Hint: Test profiles isolate test settings from production [OK]

Common Mistakes:

• Confusing test profiles with performance tuning
• Thinking test profiles generate test data automatically
• Assuming test profiles disable security permanently

2. Which of the following is the correct way to name a properties file for a test profile named testdb?

easy

A. application.properties.testdb

B. testdb-application.properties

C. application-testdb.properties

D. application_testdb.properties

Solution

1. Step 1: Recall Spring Boot profile file naming

   Spring Boot uses the pattern application-{profile}.properties for profile-specific config files.

2. Step 2: Match the pattern with the profile name

   For profile testdb, the correct file name is application-testdb.properties.

3. Final Answer:

   application-testdb.properties -> Option C

4. Quick Check:

   Profile file = application-{profile}.properties [OK]

Hint: Use application-{profile}.properties naming [OK]

Common Mistakes:

• Placing profile name after .properties
• Using underscores instead of hyphens
• Reversing the order of profile and application

3. Given the following test class annotation:
@ActiveProfiles("test")
and two property files:
application.properties with db.url=prod-db
application-test.properties with db.url=test-db
What will be the value of db.url during this test?

medium

A. prod-db

B. test-db

C. null

D. application.properties

Solution

1. Step 1: Understand @ActiveProfiles effect

   @ActiveProfiles("test") activates the 'test' profile for the test run.

2. Step 2: Determine property file precedence

   Properties in application-test.properties override those in application.properties when 'test' profile is active.

3. Final Answer:

   test-db -> Option B

4. Quick Check:

   Active profile properties override default [OK]

Hint: Active profile properties override defaults [OK]

Common Mistakes:

• Assuming default properties always apply
• Confusing profile name in annotation
• Expecting null if profile is active

4. You have a test annotated with @ActiveProfiles("dev") but the test still uses properties from application.properties instead of application-dev.properties. What is the most likely cause?

medium

A. The test class must extend a special base class to use profiles

B. The @ActiveProfiles annotation is only for production

C. Spring Boot does not support multiple profiles

D. The application-dev.properties file is missing or misnamed

Solution

1. Step 1: Check profile file presence

   If application-dev.properties is missing or named incorrectly, Spring Boot falls back to application.properties.

2. Step 2: Verify annotation usage

   @ActiveProfiles works for tests to activate profiles; it is not limited to production.

3. Final Answer:

   The application-dev.properties file is missing or misnamed -> Option D

4. Quick Check:

   Missing profile file causes fallback to default [OK]

Hint: Check profile file name and location first [OK]

Common Mistakes:

• Thinking @ActiveProfiles is ignored in tests
• Believing Spring Boot lacks profile support
• Assuming inheritance is required for profiles

5. You want to run integration tests with a profile integration that uses a different database URL and disables security. Which combination correctly activates this profile and overrides the default settings?

hard

A. Create application-integration.properties with overrides and annotate tests with @ActiveProfiles("integration")

B. Add spring.profiles.active=integration only in application.properties

C. Use @Profile("integration") on the test class without any properties file

D. Set environment variable SPRING_PROFILE=integration but keep default properties unchanged

Solution

1. Step 1: Use profile-specific properties file

   Create application-integration.properties to override database URL and security settings for the integration profile.

2. Step 2: Activate profile in tests

   Annotate tests with @ActiveProfiles("integration") to activate the profile during test runs.

3. Final Answer:

   Create application-integration.properties with overrides and annotate tests with @ActiveProfiles("integration") -> Option A

4. Quick Check:

   Profile file + @ActiveProfiles activates test config [OK]

Hint: Use profile file plus @ActiveProfiles to activate [OK]

Common Mistakes:

• Setting active profile only in default properties
• Using @Profile instead of @ActiveProfiles on tests
• Relying on environment variable without config changes