Using service loader to get Maven plugin context

maven-plugin-testing-harness-api/src/main/java/com/github/codeteapot/maven/plugin/testing/MavenPluginContext.java

@@ -8,13 +8,20 @@
  */
 public interface MavenPluginContext {
 
+  /**
+   * Name used to determine what context implementation must be used.
+   *
+   * @return Implementation name.
+   */
+  String getName();
+
   /**
    * Set the base directory used where plug-in is executed.
    *
    * @param baseDir The new base directory. May be {@code null} for default one.
    */
   void setBaseDir(File baseDir);
-  
+
   /**
    * Set the logger used by the plug-in execution.
    *
@@ -26,7 +33,7 @@ public interface MavenPluginContext {
    * Injects a Plexus component with the given role.
    *
    * @param component Component to be injected.
-   * @param role Role for component lookup. 
+   * @param role Role for component lookup.
    */
   void inject(Object component, String role);
 
@@ -38,7 +45,7 @@ public interface MavenPluginContext {
    * @return A configurator for the wanted plug-in goal.
    */
   MavenPluginGoalConfigurator goal(String name);
-  
+
   /**
    * Instantiates a goal configuration.
    *

maven-plugin-testing-harness-junit-jupiter/src/main/java/com/github/codeteapot/maven/plugin/testing/junit/jupiter/MavenPluginExtension.java

@@ -1,5 +1,8 @@
 package com.github.codeteapot.maven.plugin.testing.junit.jupiter;
 
+import static java.util.ServiceLoader.load;
+import static java.util.stream.StreamSupport.stream;
+
 import com.github.codeteapot.maven.plugin.testing.MavenPluginContext;
 import org.junit.jupiter.api.extension.AfterEachCallback;
 import org.junit.jupiter.api.extension.BeforeEachCallback;
@@ -16,20 +19,17 @@
 public final class MavenPluginExtension
     implements BeforeEachCallback, AfterEachCallback, ParameterResolver {
 
-  private static final String DEFAULT_PLUGIN_CONTEXT_CLASS_NAME =
-      "com.github.codeteapot.maven.plugin.testing.plexus.PlexusMavenPluginContext";
-
   // private static final Namespace MAVEN_PLUGIN = create(
   // "com.github.codeteapot.maven.test");
 
-  String pluginContextClassName;
+  String pluginContextName;
   MavenPluginContext pluginContext;
 
   /**
    * Default constructor.
    */
   public MavenPluginExtension() {
-    pluginContextClassName = DEFAULT_PLUGIN_CONTEXT_CLASS_NAME;
+    pluginContextName = null;
     pluginContext = null;
   }
 
@@ -38,7 +38,10 @@ public MavenPluginExtension() {
    */
   @Override
   public void beforeEach(ExtensionContext context) throws Exception {
-    pluginContext = (MavenPluginContext) Class.forName(pluginContextClassName).newInstance();
+    pluginContext = stream(load(MavenPluginContext.class).spliterator(), false)
+        .filter(this::pluginContextMatch)
+        .findAny()
+        .orElseThrow(() -> new IllegalStateException("Maven plugin context is not available"));
   }
 
   /**
@@ -68,4 +71,8 @@ public Object resolveParameter(ParameterContext parameterContext,
       ExtensionContext extensionContext) throws ParameterResolutionException {
     return pluginContext;
   }
+
+  private boolean pluginContextMatch(MavenPluginContext context) {
+    return pluginContextName == null || context.getName().equals(pluginContextName);
+  }
 }

maven-plugin-testing-harness-junit-jupiter/src/test/java/com/github/codeteapot/maven/plugin/testing/junit/jupiter/MavenPluginExtensionTest.java

@@ -1,6 +1,7 @@
 package com.github.codeteapot.maven.plugin.testing.junit.jupiter;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.catchThrowable;
 import static org.mockito.Mockito.when;
 import com.github.codeteapot.maven.plugin.testing.MavenPluginContext;
 import org.junit.jupiter.api.Test;
@@ -13,27 +14,36 @@
 @ExtendWith(MockitoExtension.class)
 public class MavenPluginExtensionTest {
 
-  private static final String PLEXUS_PLUGIN_CONTEXT_CLASS_NAME =
-      "com.github.codeteapot.maven.plugin.testing.plexus.PlexusMavenPluginContext";
-  private static final String TEST_PLUGIN_CONTEXT_CLASS_NAME =
-      "com.github.codeteapot.maven.plugin.testing.junit.jupiter.TestMavenPluginContext";
-
+  private static final String TEST_PLUGIN_CONTEXT_NAME = "test";
   private static final MavenPluginContext TEST_MAVEN_PLUGIN_CONTEXT = new TestMavenPluginContext();
 
+  private static final String UNAVAILABLE_PLUGIN_CONTEXT_NAME = "%%%unavailable%%%";
+
   @Mock
   private ExtensionContext extensionContext;
 
   @Test
-  public void plexusAsDefaultPluginContext() {
+  public void withoutDefaultPluginContext() {
     MavenPluginExtension extension = new MavenPluginExtension();
 
-    assertThat(extension.pluginContextClassName).isEqualTo(PLEXUS_PLUGIN_CONTEXT_CLASS_NAME);
+    assertThat(extension.pluginContextName).isNull();
   }
 
   @Test
-  public void createContextBeforeEachTest() throws Exception {
+  public void createTestContextBeforeEachTest() throws Exception {
+    MavenPluginExtension extension = new MavenPluginExtension();
+    extension.pluginContextName = TEST_PLUGIN_CONTEXT_NAME;
+    extension.pluginContext = null;
+
+    extension.beforeEach(extensionContext);
+
+    assertThat(extension.pluginContext).isInstanceOf(TestMavenPluginContext.class);
+  }
+
+  @Test
+  public void createAnyContextBeforeEachTest() throws Exception {
     MavenPluginExtension extension = new MavenPluginExtension();
-    extension.pluginContextClassName = TEST_PLUGIN_CONTEXT_CLASS_NAME;
+    extension.pluginContextName = null;
     extension.pluginContext = null;
 
     extension.beforeEach(extensionContext);
@@ -64,16 +74,26 @@ public void supportsMavenPluginContextParameter(
 
     assertThat(supports).isTrue();
   }
-  
+
   @Test
   public void resolveMavenPluginContextParameter(@Mock ParameterContext parameterContext) {
     MavenPluginExtension extension = new MavenPluginExtension();
     extension.pluginContext = TEST_MAVEN_PLUGIN_CONTEXT;
-    
+
     Object resolvedParameter = extension.resolveParameter(parameterContext, extensionContext);
-    
+
     assertThat(resolvedParameter).isEqualTo(TEST_MAVEN_PLUGIN_CONTEXT);
   }
+
+  @Test
+  public void failWhenPluginContextIsNotAvailable() {
+    MavenPluginExtension extension = new MavenPluginExtension();
+    extension.pluginContextName = UNAVAILABLE_PLUGIN_CONTEXT_NAME;
+
+    Throwable e = catchThrowable(() -> extension.beforeEach(extensionContext));
+
+    assertThat(e).isInstanceOf(IllegalStateException.class);
+  }
 
   @SuppressWarnings("unused")
   private void parameterSupport(MavenPluginContext mavenPluginContext) {

maven-plugin-testing-harness-junit-jupiter/src/test/java/com/github/codeteapot/maven/plugin/testing/junit/jupiter/TestMavenPluginContext.java

@@ -5,9 +5,16 @@
 import com.github.codeteapot.maven.plugin.testing.logger.MavenPluginLogger;
 import java.io.File;
 
-class TestMavenPluginContext implements MavenPluginContext {
+public class TestMavenPluginContext implements MavenPluginContext {
 
-  TestMavenPluginContext() {}
+  private static final String NAME = "test";
+
+  public TestMavenPluginContext() {}
+
+  @Override
+  public String getName() {
+    return NAME;
+  }
 
   @Override
   public void setBaseDir(File baseDir) {

maven-plugin-testing-harness-junit-jupiter/src/test/resources/META-INF/services/com.github.codeteapot.maven.plugin.testing.MavenPluginContext

@@ -0,0 +1 @@
+com.github.codeteapot.maven.plugin.testing.junit.jupiter.TestMavenPluginContext

maven-plugin-testing-harness-plexus/src/main/java/com/github/codeteapot/maven/plugin/testing/plexus/PlexusMavenPluginContext.java

@@ -12,6 +12,7 @@
  */
 public class PlexusMavenPluginContext implements MavenPluginContext {
 
+  private static final String NAME = "plexus";
   private static final String DESCRIPTOR_PATH = "/META-INF/maven/plugin.xml";
 
   private final Set<PlexusInjectionCommand> injectionCommandSet;
@@ -29,6 +30,11 @@ public PlexusMavenPluginContext() {
     logger = null;
     descriptorPath = DESCRIPTOR_PATH;
   }
+
+  @Override
+  public String getName() {
+    return NAME;
+  }
 
   @Override
   public void setBaseDir(File baseDir) {

maven-plugin-testing-harness-plexus/src/main/resources/META-INF/services/com.github.codeteapot.maven.plugin.testing.MavenPluginContext

@@ -0,0 +1 @@
+com.github.codeteapot.maven.plugin.testing.plexus.PlexusMavenPluginContext

maven-plugin-testing-harness-plexus/src/test/java/com/github/codeteapot/maven/plugin/testing/plexus/PlexusMavenPluginContextTest.java

@@ -9,11 +9,14 @@
 import static com.github.codeteapot.maven.plugin.testing.logger.MavenPluginLoggerMessageLevel.LOG_WARN;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
+import static java.util.ServiceLoader.load;
+import static java.util.stream.StreamSupport.stream;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.catchThrowable;
 import static org.mockito.ArgumentMatchers.argThat;
 import static org.mockito.Mockito.inOrder;
 import static org.mockito.Mockito.when;
+import com.github.codeteapot.maven.plugin.testing.MavenPluginContext;
 import com.github.codeteapot.maven.plugin.testing.logger.MavenPluginLogger;
 import java.io.BufferedReader;
 import java.io.File;
@@ -33,6 +36,8 @@
 @ExtendWith(MockitoExtension.class)
 public class PlexusMavenPluginContextTest {
 
+  private static final String PLEXUS_PLUGIN_CONTEXT_NAME = "plexus";
+
   private static final String OPERATION_FACTORY_ROLE =
       "com.github.codeteapot.maven.plugin.testing.plexus.OperationFactory";
 
@@ -50,6 +55,7 @@ public class PlexusMavenPluginContextTest {
 
   private static final String SOME_OPERAND_VALUE = "1";
 
+
   private PlexusMavenPluginContext context;
 
   @Mock
@@ -62,7 +68,11 @@ public class PlexusMavenPluginContextTest {
 
   @BeforeEach
   public void setUp(@TempDir File baseDir) {
-    context = new PlexusMavenPluginContext();
+    context = stream(load(MavenPluginContext.class).spliterator(), false)
+        .filter(ctx -> ctx.getName().equals(PLEXUS_PLUGIN_CONTEXT_NAME))
+        .findAny()
+        .map(PlexusMavenPluginContext.class::cast)
+        .get();
     context.setBaseDir(baseDir);
     context.inject(operationFactory, OPERATION_FACTORY_ROLE);
 
@@ -191,7 +201,7 @@ public void executeWithErrorWhenLoadingPlugin() throws Exception {
 
     assertThat(e).isNotNull();
   }
-  
+
   @Test
   public void executeWithErrorWhenLookingForGoal() throws Exception {
     context.descriptorPath = TEST_DESCRIPTOR_PATH;