Capture request-level metrics (path, status, client platform/version).

service/src/test/java/org/whispersystems/textsecuregcm/metrics/MetricsRequestEventListenerTest.java

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+package org.whispersystems.textsecuregcm.metrics;
+
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.Tag;
+import org.bouncycastle.ocsp.Req;
+import org.glassfish.jersey.server.ContainerRequest;
+import org.glassfish.jersey.server.ContainerResponse;
+import org.glassfish.jersey.server.ExtendedUriInfo;
+import org.glassfish.jersey.server.monitoring.RequestEvent;
+import org.glassfish.jersey.uri.UriTemplate;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.ArgumentCaptor;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Optional;
+import java.util.Set;
+
+import static org.junit.Assert.*;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+public class MetricsRequestEventListenerTest {
+
+    private MeterRegistry               meterRegistry;
+    private Counter                     counter;
+
+    private MetricsRequestEventListener listener;
+
+    @Before
+    public void setup() {
+        meterRegistry = mock(MeterRegistry.class);
+        counter       = mock(Counter.class);
+
+        listener      = new MetricsRequestEventListener(meterRegistry);
+    }
+
+    @Test
+    @SuppressWarnings("unchecked")
+    public void testOnEvent() {
+        final String path = "/test";
+        final int statusCode = 200;
+
+        final ExtendedUriInfo uriInfo = mock(ExtendedUriInfo.class);
+        when(uriInfo.getMatchedTemplates()).thenReturn(Collections.singletonList(new UriTemplate(path)));
+
+        final ContainerRequest request = mock(ContainerRequest.class);
+        when(request.getRequestHeader("User-Agent")).thenReturn(Collections.singletonList("Signal-Android 4.53.7 (Android 8.1)"));
+
+        final ContainerResponse response = mock(ContainerResponse.class);
+        when(response.getStatus()).thenReturn(statusCode);
+
+        final RequestEvent event = mock(RequestEvent.class);
+        when(event.getType()).thenReturn(RequestEvent.Type.FINISHED);
+        when(event.getUriInfo()).thenReturn(uriInfo);
+        when(event.getContainerRequest()).thenReturn(request);
+        when(event.getContainerResponse()).thenReturn(response);
+
+        final ArgumentCaptor<Iterable<Tag>> tagCaptor = ArgumentCaptor.forClass(Iterable.class);
+        when(meterRegistry.counter(eq(MetricsRequestEventListener.COUNTER_NAME), any(Iterable.class))).thenReturn(counter);
+
+        listener.onEvent(event);
+
+        verify(meterRegistry).counter(eq(MetricsRequestEventListener.COUNTER_NAME), tagCaptor.capture());
+
+        final Iterable<Tag> tagIterable = tagCaptor.getValue();
+        final Set<Tag> tags = new HashSet<>();
+
+        for (final Tag tag : tagIterable) {
+            tags.add(tag);
+        }
+
+        assertEquals(4, tags.size());
+        assertTrue(tags.contains(Tag.of(MetricsRequestEventListener.PATH_TAG, path)));
+        assertTrue(tags.contains(Tag.of(MetricsRequestEventListener.STATUS_CODE_TAG, String.valueOf(statusCode))));
+        assertTrue(tags.contains(Tag.of(MetricsRequestEventListener.PLATFORM_TAG, "android")));
+        assertTrue(tags.contains(Tag.of(MetricsRequestEventListener.VERSION_TAG, "4.53.7")));
+    }
+
+    @Test
+    public void testGetPathTemplate() {
+        final UriTemplate firstComponent = new UriTemplate("/first");
+        final UriTemplate secondComponent = new UriTemplate("/second");
+        final UriTemplate thirdComponent = new UriTemplate("/{param}/{moreDifferentParam}");
+
+        final ExtendedUriInfo uriInfo = mock(ExtendedUriInfo.class);
+        when(uriInfo.getMatchedTemplates()).thenReturn(Arrays.asList(thirdComponent, secondComponent, firstComponent));
+
+        assertEquals("/first/second/{param}/{moreDifferentParam}", MetricsRequestEventListener.getPathTemplate(uriInfo));
+    }
+
+    @Test
+    public void testGetUserAgentTags() {
+        assertEquals(MetricsRequestEventListener.UNRECOGNIZED_TAGS,
+                listener.getUserAgentTags("This is obviously not a reasonable User-Agent string."));
+
+        final List<Tag> tags = listener.getUserAgentTags("Signal-Android 4.53.7 (Android 8.1)");
+
+        assertEquals(2, tags.size());
+        assertTrue(tags.contains(Tag.of(MetricsRequestEventListener.PLATFORM_TAG, "android")));
+        assertTrue(tags.contains(Tag.of(MetricsRequestEventListener.VERSION_TAG, "4.53.7")));
+    }
+
+    @Test
+    public void testGetUserAgentTagsFlooded() {
+        for (int i = 0; i < MetricsRequestEventListener.MAX_VERSIONS; i++) {
+            listener.getUserAgentTags(String.format("Signal-Android 1.0.%d (Android 8.1)", i));
+        }
+
+        assertEquals(MetricsRequestEventListener.OVERFLOW_TAGS,
+                listener.getUserAgentTags("Signal-Android 2.0.0 (Android 8.1)"));
+
+        final List<Tag> tags = listener.getUserAgentTags("Signal-Android 1.0.0 (Android 8.1)");
+
+        assertEquals(2, tags.size());
+        assertTrue(tags.contains(Tag.of(MetricsRequestEventListener.PLATFORM_TAG, "android")));
+        assertTrue(tags.contains(Tag.of(MetricsRequestEventListener.VERSION_TAG, "1.0.0")));
+    }
+}