Add an PlexusExtension#setContext protected method

Author: gnodet

src/main/java/org/codehaus/plexus/testing/PlexusExtension.java

@@ -74,7 +74,8 @@ public class PlexusExtension implements BeforeEachCallback, AfterEachCallback {
     @Override
     public void beforeEach(ExtensionContext context) throws Exception {
         basedir = getBasedir();
-        this.context = context;
+
+        setContext(context);
 
         getContainer().addComponent(getContainer(), PlexusContainer.class.getName());
 
@@ -83,6 +84,10 @@ public void beforeEach(ExtensionContext context) throws Exception {
                         Collections.emptyList(), binder -> binder.requestInjection(context.getRequiredTestInstance()));
     }
 
+    protected void setContext(ExtensionContext context) {
+        this.context = context;
+    }
+
     @SuppressWarnings("ResultOfMethodCallIgnored")
     protected void setupContainer() {
         // ----------------------------------------------------------------------------