[JUnit Platform] Warn if feature files could not be found

Both Surefire and Gradle assume that tests are contained within a class and
use `ClassSelector` to discover tests in these classes. Cucumber uses plain
text files. By using a class annotated with `@Cucumber` we work around this
behaviour. Cucumber will then scan the package and sub-packages of the
annotated class for feature files.

When using this system, in case of misconfiguration it is not immediately clear
if the test engine is not picked up or if the location of the feature files and
annotated class do not line up.

While we can not generically log a warning in case a discovery selector did not
find any features, we can log a warning in this special case. It is clear that
the intend was to put feature files in the package. Otherwise the annotated
class could/should be removed to suppress this warning.

Fixes: #2179

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## [Unreleased] (In Git)
 
 ### Added
+ * [JUnit Platform] Warn if feature files could not be found ([#2179](https://github.com/cucumber/cucumber-jvm/issues/2179) M.P. Korstanje)
 
 ### Changed
 

junit-platform-engine/src/main/java/io/cucumber/junit/platform/engine/CucumberEngineExecutionContext.java

@@ -3,6 +3,8 @@
 import io.cucumber.core.eventbus.EventBus;
 import io.cucumber.core.gherkin.Feature;
 import io.cucumber.core.gherkin.Pickle;
+import io.cucumber.core.logging.Logger;
+import io.cucumber.core.logging.LoggerFactory;
 import io.cucumber.core.plugin.PluginFactory;
 import io.cucumber.core.plugin.Plugins;
 import io.cucumber.core.runtime.BackendServiceLoader;
@@ -20,8 +22,6 @@
 import io.cucumber.core.runtime.TimeServiceEventBus;
 import io.cucumber.core.runtime.TypeRegistryConfigurerSupplier;
 import org.apiguardian.api.API;
-import org.junit.platform.commons.logging.Logger;
-import org.junit.platform.commons.logging.LoggerFactory;
 import org.junit.platform.engine.ConfigurationParameters;
 import org.junit.platform.engine.support.hierarchical.EngineExecutionContext;
 

junit-platform-engine/src/main/java/io/cucumber/junit/platform/engine/FeatureResolver.java

@@ -4,6 +4,8 @@
 import io.cucumber.core.feature.FeatureParser;
 import io.cucumber.core.gherkin.Feature;
 import io.cucumber.core.gherkin.Pickle;
+import io.cucumber.core.logging.Logger;
+import io.cucumber.core.logging.LoggerFactory;
 import io.cucumber.core.resource.ClassLoaders;
 import io.cucumber.core.resource.ResourceScanner;
 import io.cucumber.plugin.event.Node;
@@ -20,6 +22,7 @@
 import org.junit.platform.engine.discovery.UriSelector;
 
 import java.net.URI;
+import java.util.List;
 import java.util.UUID;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
@@ -29,6 +32,8 @@
 
 final class FeatureResolver {
 
+    private static final Logger log = LoggerFactory.getLogger(FeatureResolver.class);
+
     private final FeatureParser featureParser = new FeatureParser(UUID::randomUUID);
     private final ResourceScanner<Feature> featureScanner = new ResourceScanner<>(
         ClassLoaders::getDefaultClassLoader,
@@ -142,20 +147,33 @@ void resolvePackageResource(PackageSelector selector) {
         resolvePackageResource(selector.getPackageName());
     }
 
-    private void resolvePackageResource(String packageName) {
-        featureScanner
-                .scanForResourcesInPackage(packageName, packageFilter)
+    private List<Feature> resolvePackageResource(String packageName) {
+        List<Feature> features = featureScanner
+                .scanForResourcesInPackage(packageName, packageFilter);
+
+        features
                 .stream()
                 .sorted(comparing(Feature::getUri))
                 .map(this::createFeatureDescriptor)
                 .forEach(engineDescriptor::mergeFeature);
+
+        return features;
     }
 
     void resolveClass(ClassSelector classSelector) {
         Class<?> javaClass = classSelector.getJavaClass();
         Cucumber annotation = javaClass.getAnnotation(Cucumber.class);
         if (annotation != null) {
-            resolvePackageResource(javaClass.getPackage().getName());
+            // We know now the intention is to run feature files in the
+            // package of the annotated class.
+            resolvePackageResourceWarnIfNone(javaClass.getPackage().getName());
+        }
+    }
+
+    private void resolvePackageResourceWarnIfNone(String packageName) {
+        List<Feature> features = resolvePackageResource(packageName);
+        if (features.isEmpty()) {
+            log.warn(() -> "No features found in package '" + packageName + "'");
         }
     }
 

junit-platform-engine/src/test/java/io/cucumber/junit/platform/engine/DiscoverySelectorResolverTest.java

@@ -1,7 +1,11 @@
 package io.cucumber.junit.platform.engine;
 
+import io.cucumber.core.logging.LogRecordListener;
+import io.cucumber.core.logging.LoggerFactory;
+import io.cucumber.junit.platform.engine.nofeatures.NoFeatures;
 import org.hamcrest.CustomTypeSafeMatcher;
 import org.hamcrest.Matcher;
+import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.platform.engine.ConfigurationParameters;
@@ -27,8 +31,11 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
+import java.util.logging.Level;
+import java.util.logging.LogRecord;
 import java.util.stream.Collectors;
 
+import static java.util.Collections.emptyList;
 import static java.util.Collections.singleton;
 import static java.util.Comparator.comparing;
 import static java.util.stream.Collectors.toSet;
@@ -46,15 +53,22 @@
 class DiscoverySelectorResolverTest {
 
     private final DiscoverySelectorResolver resolver = new DiscoverySelectorResolver();
+    private final LogRecordListener logRecordListener = new LogRecordListener();
     private CucumberEngineDescriptor testDescriptor;
 
     @BeforeEach
     void before() {
+        LoggerFactory.addListener(logRecordListener);
         UniqueId id = UniqueId.forEngine(new CucumberTestEngine().getId());
         testDescriptor = new CucumberEngineDescriptor(id);
         assertEquals(0, testDescriptor.getChildren().size());
     }
 
+    @AfterEach
+    void after() {
+        LoggerFactory.removeListener(logRecordListener);
+    }
+
     @Test
     void resolveRequestWithClasspathResourceSelector() {
         DiscoverySelector resource = selectClasspathResource("io/cucumber/junit/platform/engine/single.feature");
@@ -349,6 +363,19 @@ void resolveRequestWithClassSelector() {
         assertEquals(5, testDescriptor.getChildren().size());
     }
 
+    @Test
+    void resolveRequestWithClassSelectorShouldLogWarnIfNoFeaturesFound() {
+        DiscoverySelector resource = selectClass(NoFeatures.class);
+        EngineDiscoveryRequest discoveryRequest = new SelectorRequest(resource);
+        resolver.resolveSelectors(discoveryRequest, testDescriptor);
+        assertEquals(0, testDescriptor.getChildren().size());
+        assertEquals(1, logRecordListener.getLogRecords().size());
+        LogRecord logRecord = logRecordListener.getLogRecords().get(0);
+        assertEquals(Level.WARNING, logRecord.getLevel());
+        assertEquals("No features found in package 'io.cucumber.junit.platform.engine.nofeatures'",
+            logRecord.getMessage());
+    }
+
     private static class SelectorRequest implements EngineDiscoveryRequest {
 
         private final Map<Class<?>, List<DiscoverySelector>> resources = new HashMap<>();

junit-platform-engine/src/test/java/io/cucumber/junit/platform/engine/nofeatures/NoFeatures.java

@@ -0,0 +1,8 @@
+package io.cucumber.junit.platform.engine.nofeatures;
+
+import io.cucumber.junit.platform.engine.Cucumber;
+
+@Cucumber
+public class NoFeatures {
+
+}