Add auto-configuration for Common Library beans and test support for @WebMvcTest

Author: mmushfiq

README.md

@@ -95,18 +95,8 @@ implementation "com.company.project:springboot-microservice-common-lib:${pnCommo
 **Note:** This common library is not yet available in the central repository. To use it locally, clone this repository and execute `gradle publishToMavenLocal` to publish it to your local Maven repository.
 
 ### Bean Detection Configuration
-To ensure that Spring detects and registers the beans provided by this common library, add the following class to the config package of your microservice:
-
-```java
-import org.springframework.context.annotation.ComponentScan;
-import org.springframework.context.annotation.Configuration;
-
-@Configuration
-@ComponentScan(basePackages = "com.company.project.common")
-public class CommonLibScannerConfig {
-}
-```
-This will enable automatic scanning and registration of common library components.
+The Common Library provides Spring Boot auto-configuration, so you do not need to manually add any @ComponentScan in your microservice.
+When the library is on the classpath all components, services, and configurations inside com.company.project.common are automatically detected and registered.
 
 
 ## Reference Implementation

build.gradle

@@ -81,6 +81,9 @@ dependencies {
     annotationProcessor "org.mapstruct:mapstruct-processor:${mapstructVersion}"
     implementation "net.ttddyy.observation:datasource-micrometer-spring-boot:${datasourceMicrometerVersion}"
     implementation "org.codehaus.janino:janino:${codehausJaninoVersion}"
+
+    testImplementation "org.mockito:mockito-core"
+    testImplementation "org.springframework.boot:spring-boot-starter-test"
 }
 
 dependencyManagement {

gradle.properties

@@ -1,4 +1,4 @@
-projectVersion = 0.0.1
+projectVersion = 0.0.2
 springBootVersion = 3.3.3
 springdocStarterVersion = 2.4.0
 logstashLogbackVersion = 7.4

src/main/java/com/company/project/common/config/CommonLibAutoConfig.java

@@ -0,0 +1,19 @@
+package com.company.project.common.config;
+
+import org.springframework.boot.autoconfigure.AutoConfiguration;
+import org.springframework.context.annotation.ComponentScan;
+
+/**
+ * Auto-configuration entry point for the Common Library.
+ *
+ * <p>Registers all Common Library components by performing a component scan on
+ * {@code com.company.project.common}. This allows applications to use the
+ * library without manually adding a {@code @ComponentScan} in their own code.
+ *
+ * <p>Loaded automatically when the Common Library is on the classpath and
+ * Spring Boot auto-configuration is enabled.
+ */
+@AutoConfiguration
+@ComponentScan(basePackages = {"com.company.project.common"})
+public class CommonLibAutoConfig {
+}

src/main/java/com/company/project/common/test/WebMvcTestImportSelector.java

@@ -0,0 +1,36 @@
+package com.company.project.common.test;
+
+import com.company.project.common.config.CommonLibAutoConfig;
+import lombok.extern.slf4j.Slf4j;
+import org.jetbrains.annotations.NotNull;
+import org.springframework.context.annotation.ImportSelector;
+import org.springframework.core.type.AnnotationMetadata;
+
+/**
+ * Import selector that automatically loads Common Library configuration classes
+ * during {@code @WebMvcTest} tests.
+ *
+ * <p>This class is registered via Spring Boot’s Test Import Selector SPI
+ * ({@code META-INF/spring/org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest.imports})
+ * so that the following configurations are applied only in MVC slice tests:
+ * <ul>
+ *   <li>{@code CommonLibAutoConfig} – main Common Library auto-configuration</li>
+ *   <li>{@code WebMvcTestMockConfig} – test-only mocks/stubs (e.g., Tracer)</li>
+ * </ul>
+ * This allows consumer applications to use {@code @WebMvcTest} without manually
+ * importing Common Library test configuration.
+ */
+@Slf4j
+public class WebMvcTestImportSelector implements ImportSelector {
+
+    @NotNull
+    @Override
+    public String[] selectImports(@NotNull AnnotationMetadata metadata) {
+        log.info("WebMvcTestImportSelector loaded");
+        return new String[] {
+                CommonLibAutoConfig.class.getName(),
+                WebMvcTestMockConfig.class.getName()
+        };
+    }
+
+}

src/main/java/com/company/project/common/test/WebMvcTestMockConfig.java

@@ -0,0 +1,52 @@
+package com.company.project.common.test;
+
+import com.company.project.common.config.OpenTelemetryConfig;
+import io.micrometer.tracing.Tracer;
+import java.lang.reflect.Method;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Test-only auto-configuration for the Common Library.
+ *
+ * <p>Provides Mockito-based mock beans (e.g., {@link Tracer} and
+ * {@link OpenTelemetryConfig}) required for {@code @WebMvcTest} and other
+ * slice tests. This configuration activates only when Mockito is present on the
+ * classpath, thanks to {@link ConditionalOnClass}.</p>
+ *
+ * <p>The mocks are created reflectively to avoid introducing a compile-time
+ * Mockito dependency into the main library module, ensuring they are used only
+ * in test environments.</p>
+ *
+ * <p>This class is typically imported automatically via the
+ * {@code WebMvcTest.imports} SPI defined in the Common Library's
+ * {@code META-INF/spring} resources.</p>
+ */
+@ConditionalOnClass(name = "org.mockito.Mockito")
+@Configuration
+public class WebMvcTestMockConfig {
+
+    @Bean
+    public Tracer tracer() {
+        return createMock(Tracer.class);
+    }
+
+    @Bean
+    public OpenTelemetryConfig openTelemetryConfig() {
+        return createMock(OpenTelemetryConfig.class);
+    }
+
+    @SuppressWarnings("unchecked")
+    private <T> T createMock(Class<T> type) {
+        try {
+            Class<?> mockitoClass = Class.forName("org.mockito.Mockito");
+            Method m = mockitoClass.getMethod("mock", Class.class);
+            Object mocked = m.invoke(null, type);
+            return (T) mocked;
+        } catch (Exception ex) {
+            throw new RuntimeException("Failed to create mock reflectively", ex);
+        }
+    }
+
+}

src/main/resources/META-INF/LICENSE.txt

@@ -0,0 +1,22 @@
+MIT License
+
+Copyright (c) 2025 CommonLibrary
+Author: Mushfig Mammadov (mushfiqazeri@gmail.com)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -0,0 +1 @@
+com.company.project.common.config.CommonLibAutoConfig

src/main/resources/META-INF/spring/org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest.imports

@@ -0,0 +1 @@
+com.company.project.common.test.WebMvcTestImportSelector