Use default pom.xml when Basedir is set

When Basedir is explicit set we can try to find a pom.xml
we can not use a default pom.xml with default basedir which point to project basedir

Author: slawekjaranowski

maven-plugin-testing-harness/src/main/java/org/apache/maven/api/plugin/testing/MojoExtension.java

@@ -28,6 +28,7 @@
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.net.URL;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
@@ -139,6 +140,8 @@ public class MojoExtension extends PlexusExtension implements ParameterResolver
     // Namespace for storing/retrieving data related to MojoExtension
     private static final ExtensionContext.Namespace MOJO_EXTENSION = ExtensionContext.Namespace.create("MojoExtension");
 
+    public static final String BASEDIR_IS_SET_KEY = "basedirIsSet";
+
     @Override
     public boolean supportsParameter(ParameterContext parameterContext, ExtensionContext extensionContext)
             throws ParameterResolutionException {
@@ -178,7 +181,13 @@ public Object resolveParameter(ParameterContext parameterContext, ExtensionConte
     public void beforeEach(ExtensionContext context) throws Exception {
         String basedir = AnnotationSupport.findAnnotation(context.getElement().get(), Basedir.class)
                 .map(Basedir::value)
-                .orElseGet(PlexusExtension::getBasedir);
+                .orElse(null);
+
+        if (basedir == null) {
+            basedir = getBasedir();
+        } else {
+            context.getStore(MOJO_EXTENSION).put(BASEDIR_IS_SET_KEY, Boolean.TRUE);
+        }
 
         URL resource = context.getRequiredTestClass().getResource(basedir);
         if (resource != null) {
@@ -315,6 +324,14 @@ private Mojo lookupMojo(
         } else if (!pom.isEmpty()) {
             Path path = basedir.resolve(pom);
             pomDom = Xpp3DomBuilder.build(new XmlStreamReader(path.toFile()));
+        } else if (isBasedirSet(extensionContext)) {
+            // only look for a pom.xml if basedir is explicitly set
+            Path path = basedir.resolve("pom.xml");
+            if (Files.exists(path)) {
+                pomDom = Xpp3DomBuilder.build(new XmlStreamReader(path.toFile()));
+            } else {
+                pomDom = new Xpp3Dom("");
+            }
         } else {
             pomDom = new Xpp3Dom("");
         }
@@ -334,6 +351,10 @@ private Mojo lookupMojo(
         return lookupMojo(extensionContext, coord, pluginConfiguration, descriptor);
     }
 
+    private boolean isBasedirSet(ExtensionContext extensionContext) {
+        return extensionContext.getStore(MOJO_EXTENSION).getOrDefault(BASEDIR_IS_SET_KEY, Boolean.class, Boolean.FALSE);
+    }
+
     protected String[] mojoCoordinates(String goal, PluginDescriptor pluginDescriptor) throws Exception {
         if (goal.matches(".*:.*:.*:.*")) {
             return goal.split(":");

maven-plugin-testing-harness/src/test/java/org/apache/maven/plugin/testing/ParametersMojoTest.java

@@ -124,4 +124,20 @@ void basedirInjectedWithBasedirFromClasspathAnnotation(ParametersMojo mojo) {
         assertEquals("i-have-a-basedir-set-by-annotation-classpath", mojo.getPlain());
         assertDoesNotThrow(mojo::execute);
     }
+
+    @Test
+    @Basedir("src/test/projects/basedir-set-by-annotation")
+    @InjectMojo(goal = "test:test-plugin:0.0.1-SNAPSHOT:parameters")
+    void basedirInjectedWithBasedirAnnotationDefaultPom(ParametersMojo mojo) {
+        assertEquals("i-have-a-basedir-set-by-annotation", mojo.getPlain());
+        assertDoesNotThrow(mojo::execute);
+    }
+
+    @Test
+    @Basedir("/projects/basedir-set-by-annotation-classpath")
+    @InjectMojo(goal = "parameters")
+    void basedirInjectedWithBasedirFromClasspathAnnotationDefaultPom(ParametersMojo mojo) {
+        assertEquals("i-have-a-basedir-set-by-annotation-classpath", mojo.getPlain());
+        assertDoesNotThrow(mojo::execute);
+    }
 }