Feature/bael 2515 override properties (#7165)

* [ BAEL-2515] : Add override properties article

* [ BAEL-2515] : Rename tests

* [ BAEL-2515 ]: Remove hyperlink from README

spring-boot-testing/README.MD

@@ -6,3 +6,4 @@ The "REST With Spring" Classes: http://bit.ly/restwithspring
 - [Testing with Spring and Spock](https://www.baeldung.com/spring-spock-testing)
 - [Exclude Auto-Configuration Classes in Spring Boot Tests](https://www.baeldung.com/spring-boot-exclude-auto-configuration-test)
 - [Setting the Log Level in Spring Boot when Testing](https://www.baeldung.com/spring-boot-testing-log-level)
+- [Override properties in Spring]

spring-boot-testing/src/main/java/com/baeldung/overrideproperties/Application.java

@@ -0,0 +1,11 @@
+package com.baeldung.overrideproperties;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+}

spring-boot-testing/src/main/java/com/baeldung/overrideproperties/resolver/PropertySourceResolver.java

@@ -0,0 +1,24 @@
+package com.baeldung.overrideproperties.resolver;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Component;
+
+@Component
+public class PropertySourceResolver {
+
+    private final String firstProperty;
+    private final String secondProperty;
+
+    public PropertySourceResolver(@Value("${example.firstProperty}") String firstProperty, @Value("${example.secondProperty}") String secondProperty) {
+        this.firstProperty = firstProperty;
+        this.secondProperty = secondProperty;
+    }
+
+    public String getFirstProperty() {
+        return firstProperty;
+    }
+
+    public String getSecondProperty() {
+        return secondProperty;
+    }
+}

spring-boot-testing/src/test/java/com/baeldung/overrideproperties/ContextPropertySourceResolverIntegrationTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.overrideproperties;
+
+import com.baeldung.overrideproperties.resolver.PropertySourceResolver;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.junit.Assert.assertEquals;
+
+@RunWith(SpringRunner.class)
+@ContextConfiguration(initializers = PropertyOverrideContextInitializer.class, classes = Application.class)
+public class ContextPropertySourceResolverIntegrationTest {
+
+    @Autowired private PropertySourceResolver propertySourceResolver;
+
+    @Test
+    public void shouldContext_overridePropertyValues() {
+        final String firstProperty = propertySourceResolver.getFirstProperty();
+        final String secondProperty = propertySourceResolver.getSecondProperty();
+
+        assertEquals(PropertyOverrideContextInitializer.PROPERTY_FIRST_VALUE, firstProperty);
+        assertEquals("contextFile", secondProperty);
+    }
+
+}

spring-boot-testing/src/test/java/com/baeldung/overrideproperties/ProfilePropertySourceResolverIntegrationTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.overrideproperties;
+
+import com.baeldung.overrideproperties.resolver.PropertySourceResolver;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.junit.Assert.assertEquals;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+@ActiveProfiles("test")
+public class ProfilePropertySourceResolverIntegrationTest {
+
+    @Autowired private PropertySourceResolver propertySourceResolver;
+
+    @Test
+    public void shouldProfiledProperty_overridePropertyValues() {
+        final String firstProperty = propertySourceResolver.getFirstProperty();
+        final String secondProperty = propertySourceResolver.getSecondProperty();
+
+        assertEquals("profile", firstProperty);
+        assertEquals("file", secondProperty);
+    }
+
+}

spring-boot-testing/src/test/java/com/baeldung/overrideproperties/PropertyOverrideContextInitializer.java

@@ -0,0 +1,17 @@
+package com.baeldung.overrideproperties;
+
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.test.context.support.TestPropertySourceUtils;
+
+public class PropertyOverrideContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
+
+    static final String PROPERTY_FIRST_VALUE = "contextClass";
+
+    @Override
+    public void initialize(ConfigurableApplicationContext configurableApplicationContext) {
+        TestPropertySourceUtils.addInlinedPropertiesToEnvironment(configurableApplicationContext, "example.firstProperty=" + PROPERTY_FIRST_VALUE);
+
+        TestPropertySourceUtils.addPropertiesFilesToEnvironment(configurableApplicationContext, "context-override-application.properties");
+    }
+}

spring-boot-testing/src/test/java/com/baeldung/overrideproperties/SpringBootPropertySourceResolverIntegrationTest.java

@@ -0,0 +1,26 @@
+package com.baeldung.overrideproperties;
+
+import com.baeldung.overrideproperties.resolver.PropertySourceResolver;
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(properties = { "example.firstProperty=annotation" })
+public class SpringBootPropertySourceResolverIntegrationTest {
+
+    @Autowired private PropertySourceResolver propertySourceResolver;
+
+    @Test
+    public void shouldSpringBootTestAnnotation_overridePropertyValues() {
+        final String firstProperty = propertySourceResolver.getFirstProperty();
+        final String secondProperty = propertySourceResolver.getSecondProperty();
+
+        Assert.assertEquals("annotation", firstProperty);
+        Assert.assertEquals("file", secondProperty);
+    }
+
+}

spring-boot-testing/src/test/java/com/baeldung/overrideproperties/TestResourcePropertySourceResolverIntegrationTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.overrideproperties;
+
+import com.baeldung.overrideproperties.resolver.PropertySourceResolver;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.junit.Assert.assertEquals;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class TestResourcePropertySourceResolverIntegrationTest {
+
+    @Autowired private PropertySourceResolver propertySourceResolver;
+
+    @Test
+    public void shouldTestResourceFile_overridePropertyValues() {
+        final String firstProperty = propertySourceResolver.getFirstProperty();
+        final String secondProperty = propertySourceResolver.getSecondProperty();
+
+        assertEquals("file", firstProperty);
+        assertEquals("file", secondProperty);
+    }
+
+}

spring-boot-testing/src/test/resources/application-test.properties

@@ -0,0 +1,5 @@
+# test properties
+spring.autoconfigure.exclude=org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration
+
+# override properties
+example.firstProperty=profile

spring-boot-testing/src/test/resources/application.properties

@@ -0,0 +1,7 @@
+# security
+spring.security.user.name=john
+spring.security.user.password=123
+
+# override properties
+example.firstProperty=file
+example.secondProperty=file

spring-boot-testing/src/test/resources/context-override-application.properties

@@ -0,0 +1 @@
+example.secondProperty=contextFile