BAEL-7758: How to Test a Spring AOP Aspect (#16511)

Author: manfred106

spring-aop-2/src/main/java/com/baeldung/springaop/unittest/ArraySorting.java

@@ -0,0 +1,15 @@
+package com.baeldung.springaop.unittest;
+
+import org.springframework.stereotype.Component;
+
+import java.util.Collections;
+import java.util.List;
+
+@Component
+public class ArraySorting {
+
+    public <T extends Comparable<? super T>> void sort(List<T> list) {
+        Collections.sort(list);
+    }
+
+}

spring-aop-2/src/main/java/com/baeldung/springaop/unittest/ExecutionTimeAspect.java

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+package com.baeldung.springaop.unittest;
+
+import org.aspectj.lang.ProceedingJoinPoint;
+import org.aspectj.lang.annotation.Around;
+import org.aspectj.lang.annotation.Aspect;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+
+@Aspect
+@Component
+public class ExecutionTimeAspect {
+
+    private Logger logger = LoggerFactory.getLogger(ExecutionTimeAspect.class);
+
+    @Around("execution(* com.baeldung.springaop.unittest.ArraySorting.sort(..))")
+    public Object logExecutionTime(ProceedingJoinPoint joinPoint) throws Throwable {
+        long t = System.currentTimeMillis();
+        Object result = joinPoint.proceed();
+        logger.info("Execution time=" + (System.currentTimeMillis() - t) + "ms");
+        return result;
+    }
+
+}

spring-aop-2/src/test/java/com/baeldung/springaop/unittest/ExecutionTimeAspectIntegrationTest.java

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+package com.baeldung.springaop.unittest;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+@SpringBootTest
+class ExecutionTimeAspectIntegrationTest {
+
+    @Autowired
+    private ArraySorting arraySorting;
+
+    private List<Integer> getRandomNumberList(int size) {
+        List<Integer> numberList = new ArrayList<>();
+        for (int n=0;n<size;n++) {
+            numberList.add((int) Math.round(Math.random() * size));
+        }
+        return numberList;
+    }
+
+    @Test
+    void whenSort_thenExecutionTimeIsPrinted() {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        PrintStream originalSystemOut = System.out;
+        System.setOut(new PrintStream(baos));
+
+        arraySorting.sort(getRandomNumberList(10000));
+
+        System.setOut(originalSystemOut);
+        String logOutput = baos.toString();
+        assertThat(logOutput).contains("Execution time=");
+    }
+
+}

spring-aop-2/src/test/java/com/baeldung/springaop/unittest/ExecutionTimeAspectUnitTest.java

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+package com.baeldung.springaop.unittest;
+
+import org.aspectj.lang.ProceedingJoinPoint;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.slf4j.Logger;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+class ExecutionTimeAspectUnitTest {
+
+    @Mock
+    private ProceedingJoinPoint joinPoint;
+
+    @Mock
+    private Logger logger;
+
+    @InjectMocks
+    private ExecutionTimeAspect aspect;
+
+    @Test
+    void whenExecuteJoinPoint_thenLoggerInfoIsCalled() throws Throwable {
+        when(joinPoint.proceed()).thenReturn(null);
+        aspect.logExecutionTime(joinPoint);
+        verify(joinPoint, times(1)).proceed();
+        verify(logger, times(1)).info(anyString());
+    }
+
+    @Test
+    void whenExecuteJoinPoint_thenExecutionTimeIsLogged() throws Throwable {
+        when(joinPoint.proceed()).thenReturn(null);
+        aspect.logExecutionTime(joinPoint);
+        verify(joinPoint, times(1)).proceed();
+
+        ArgumentCaptor<String> argumentCaptor = ArgumentCaptor.forClass(String.class);
+        verify(logger, times(1)).info(argumentCaptor.capture());
+        assertThat(argumentCaptor.getValue()).startsWith("Execution time=");
+    }
+
+}