Test cases for metric util

Author: Pankaj Agrawal

pom.xml

@@ -182,6 +182,12 @@
                 <version>3.5.10</version>
                 <scope>test</scope>
             </dependency>
+            <dependency>
+                <groupId>org.mockito</groupId>
+                <artifactId>mockito-inline</artifactId>
+                <version>3.5.10</version>
+                <scope>test</scope>
+            </dependency>
             <dependency>
                 <groupId>org.aspectj</groupId>
                 <artifactId>aspectjweaver</artifactId>

powertools-metrics/src/main/java/software/amazon/lambda/powertools/metrics/PowertoolsMetricsLogger.java

@@ -6,7 +6,7 @@
 import software.amazon.cloudwatchlogs.emf.model.Unit;
 
 public final class PowertoolsMetricsLogger {
-    private static MetricsLogger metricsLogger = new MetricsLogger();
+    private static final MetricsLogger metricsLogger = new MetricsLogger();
 
     public static MetricsLogger metricsLogger() {
         return metricsLogger;

powertools-metrics/src/main/java/software/amazon/lambda/powertools/metrics/internal/LambdaMetricsAspect.java

@@ -44,24 +44,7 @@ public Object around(ProceedingJoinPoint pjp,
             logger.setNamespace(namespace(powertoolsMetrics))
                     .setDimensions(DimensionSet.of("service", service(powertoolsMetrics)));
 
-            MetricsLogger coldStartLogger = null;
-
-            if (powertoolsMetrics.captureColdStart()
-                    && isColdStart()) {
-
-                Optional<Context> contextOptional = extractContext(pjp);
-
-                if (contextOptional.isPresent()) {
-                    Context context = contextOptional.orElseThrow(() -> new IllegalStateException("Context not found"));
-
-                    coldStartLogger = new MetricsLogger();
-
-                    coldStartLogger.putDimensions(DimensionSet.of("function_name", context.getFunctionName()))
-                            .setDimensions(DimensionSet.of("service", service(powertoolsMetrics)))
-                            .setNamespace(namespace(powertoolsMetrics))
-                            .putMetric("ColdStart", 1, Unit.COUNT);
-                }
-            }
+            MetricsLogger coldStartLogger = coldStartSingleMetricIfApplicable(pjp, powertoolsMetrics);
 
             Object proceed = pjp.proceed(proceedArgs);
 
@@ -77,6 +60,28 @@ && isColdStart()) {
         return pjp.proceed(proceedArgs);
     }
 
+    private MetricsLogger coldStartSingleMetricIfApplicable(final ProceedingJoinPoint pjp,
+                                                            final PowertoolsMetrics powertoolsMetrics) {
+        if (powertoolsMetrics.captureColdStart()
+                && isColdStart()) {
+
+            Optional<Context> contextOptional = extractContext(pjp);
+
+            if (contextOptional.isPresent()) {
+                Context context = contextOptional.orElseThrow(() -> new IllegalStateException("Context not found"));
+
+                MetricsLogger coldStartLogger = new MetricsLogger();
+
+                return coldStartLogger.putDimensions(DimensionSet.of("function_name", context.getFunctionName()))
+                        .setDimensions(DimensionSet.of("service", service(powertoolsMetrics)))
+                        .setNamespace(namespace(powertoolsMetrics))
+                        .putMetric("ColdStart", 1, Unit.COUNT);
+            }
+        }
+
+        return null;
+    }
+
     private String namespace(PowertoolsMetrics powertoolsMetrics) {
         return !"".equals(powertoolsMetrics.namespace()) ? powertoolsMetrics.namespace() : NAMESPACE;
     }

powertools-metrics/src/test/java/software/amazon/lambda/powertools/metrics/PowertoolsMetricsLoggerTest.java

@@ -0,0 +1,74 @@
+package software.amazon.lambda.powertools.metrics;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.util.Collections;
+import java.util.Map;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.MockedStatic;
+import software.amazon.cloudwatchlogs.emf.config.SystemWrapper;
+import software.amazon.cloudwatchlogs.emf.model.DimensionSet;
+import software.amazon.cloudwatchlogs.emf.model.Unit;
+
+import static java.util.Collections.*;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mockStatic;
+
+class PowertoolsMetricsLoggerTest {
+
+    private final ByteArrayOutputStream out = new ByteArrayOutputStream();
+    private final PrintStream originalOut = System.out;
+    private final ObjectMapper mapper = new ObjectMapper();
+
+    @BeforeEach
+    void setUp() {
+        System.setOut(new PrintStream(out));
+    }
+
+    @AfterEach
+    void tearDown() {
+        System.setOut(originalOut);
+    }
+
+    @BeforeAll
+    static void beforeAll() {
+        try (MockedStatic<SystemWrapper> mocked = mockStatic(SystemWrapper.class)) {
+            mocked.when(() -> SystemWrapper.getenv("AWS_EMF_ENVIRONMENT")).thenReturn("Lambda");
+        }
+    }
+
+    @Test
+    void singleMetricsCaptureUtility() {
+        try (MockedStatic<SystemWrapper> mocked = mockStatic(SystemWrapper.class)) {
+            mocked.when(() -> SystemWrapper.getenv("AWS_EMF_ENVIRONMENT")).thenReturn("Lambda");
+
+            PowertoolsMetricsLogger.withSingleMetric("Metric1", 1, Unit.COUNT, "test",
+                    metricsLogger -> metricsLogger.setDimensions(DimensionSet.of("Dimension1", "Value1")));
+
+            assertThat(out.toString())
+                    .satisfies(s -> {
+                        Map<String, Object> logAsJson = readAsJson(s);
+
+                        assertThat(logAsJson)
+                                .containsEntry("Metric1", 1.0)
+                                .containsEntry("Dimension1", "Value1")
+                                .containsKey("_aws");
+                    });
+        }
+    }
+
+    private Map<String, Object> readAsJson(String s) {
+        try {
+            return mapper.readValue(s, Map.class);
+        } catch (JsonProcessingException e) {
+            e.printStackTrace();
+        }
+        return emptyMap();
+    }
+}

powertools-metrics/src/test/java/software/amazon/lambda/powertools/metrics/handlers/PowertoolsMetricsColdStartEnabledHandler.java

@@ -0,0 +1,21 @@
+package software.amazon.lambda.powertools.metrics.handlers;
+
+import com.amazonaws.services.lambda.runtime.Context;
+import com.amazonaws.services.lambda.runtime.RequestHandler;
+import software.amazon.cloudwatchlogs.emf.logger.MetricsLogger;
+import software.amazon.cloudwatchlogs.emf.model.Unit;
+import software.amazon.lambda.powertools.metrics.PowertoolsMetrics;
+
+import static software.amazon.lambda.powertools.metrics.PowertoolsMetricsLogger.metricsLogger;
+
+public class PowertoolsMetricsColdStartEnabledHandler implements RequestHandler<Object, Object> {
+
+    @Override
+    @PowertoolsMetrics(namespace = "ExampleApplication", service = "booking", captureColdStart = true)
+    public Object handleRequest(Object input, Context context) {
+        MetricsLogger metricsLogger = metricsLogger();
+        metricsLogger.putMetric("Metric1", 1, Unit.BYTES);
+
+        return null;
+    }
+}

powertools-metrics/src/test/java/software/amazon/lambda/powertools/metrics/handlers/PowertoolsMetricsEnabledStreamHandler.java

@@ -0,0 +1,23 @@
+package software.amazon.lambda.powertools.metrics.handlers;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import com.amazonaws.services.lambda.runtime.Context;
+import com.amazonaws.services.lambda.runtime.RequestStreamHandler;
+import software.amazon.cloudwatchlogs.emf.logger.MetricsLogger;
+import software.amazon.cloudwatchlogs.emf.model.Unit;
+import software.amazon.lambda.powertools.metrics.PowertoolsMetrics;
+
+import static software.amazon.lambda.powertools.metrics.PowertoolsMetricsLogger.metricsLogger;
+
+public class PowertoolsMetricsEnabledStreamHandler implements RequestStreamHandler {
+
+    @Override
+    @PowertoolsMetrics(namespace = "ExampleApplication", service = "booking")
+    public void handleRequest(InputStream input, OutputStream output, Context context) {
+        MetricsLogger metricsLogger = metricsLogger();
+        metricsLogger.putMetric("Metric1", 1, Unit.BYTES);
+    }
+}