Late init for better unit tests

Author: jknack

docs/asciidoc/testing.adoc

@@ -242,10 +242,15 @@ class TestApp {
 For MVC routes you might prefer to write a unit test using a mock library. No need to use 
 `MockRouter`, but it is possible too.
 
-By default the javadoc:MockRouter[] class execute the route handler. For executing the entire
-pipeline use: javadoc:MockRouter[setFullExecution].
+==== Options
 
-Unit testing is simple and easy in Jooby. The javadoc:MockRouter[] let you to execute route function,
+- javadoc:MockRouter[setFullExecution]: the javadoc:MockRouter[] class ONLY execute the route
+handler. For executing the entire pipeline use: javadoc:MockRouter[setFullExecution].
+
+- javadoc:Jooby[setLateInit]: extension modules usually run at the time they are installed it. 
+This might not be ideally for unit tests. To delay extension initialization use the javadoc:Jooby[setLateInit] mode.
+
+Unit testing is simple and easy in Jooby. The javadoc:MockRouter[] let you execute the route function,
 while the javadoc:MockContext[] allows you to create an light-weight and mutable context where
 you can set HTTP parameters, body, headers, etc.
 

jooby/src/main/java/io/jooby/Jooby.java

@@ -92,6 +92,8 @@ public class Jooby implements Router, Registry {
 
   private EnvironmentOptions environmentOptions;
 
+  private boolean lateInit;
+
   /**
    * Creates a new Jooby instance.
    */
@@ -310,7 +312,7 @@ public Jooby renderer(@Nonnull MediaType contentType, @Nonnull Renderer renderer
    * @return This application.
    */
   @Nonnull public Jooby install(@Nonnull Extension extension) {
-    if (extension.lateinit()) {
+    if (lateInit || extension.lateinit()) {
       onStarting(() -> extension.install(this));
     } else {
       try {
@@ -477,13 +479,6 @@ public Jooby errorCode(@Nonnull Class<? extends Throwable> type,
     return this.router.getServices();
   }
 
-  private Registry checkRegistry() {
-    if (registry == null) {
-      throw new IllegalStateException("No registry available");
-    }
-    return registry;
-  }
-
   /**
    * Get base application package. This is the package from where application was initialized
    * or the package of a Jooby application sub-class.
@@ -627,6 +622,21 @@ private Registry checkRegistry() {
     return this;
   }
 
+  /**
+   * Force all module to be initialized lazily at application startup time (not at
+   * creation/instantiation time).
+   *
+   * This option is present mostly for unit-test where you need to instantiated a Jooby instance
+   * without running extensions.
+   *
+   * @param lateInit True for late init.
+   * @return This application.
+   */
+  public Jooby setLateInit(boolean lateInit) {
+    this.lateInit = lateInit;
+    return this;
+  }
+
   @Override public String toString() {
     return router.toString();
   }

modules/jooby-test/src/test/java/io/jooby/LateInitTest.java

@@ -0,0 +1,28 @@
+package io.jooby;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class LateInitTest {
+
+  @Test
+  public void defaultLateInit() {
+    Jooby app = new Jooby();
+    AtomicBoolean run = new AtomicBoolean();
+    app.install(router-> run.set(true));
+    assertEquals(true, run.get());
+  }
+
+  @Test
+  public void lateInitOn() {
+    Jooby app = new Jooby();
+    AtomicBoolean run = new AtomicBoolean();
+    app.setLateInit(true);
+    app.install(router-> run.set(true));
+    assertEquals(false, run.get());
+  }
+
+}

modules/jooby-test/src/test/java/io/jooby/UnitTest.java

@@ -3,6 +3,8 @@
 import io.reactivex.Single;
 import org.junit.jupiter.api.Test;
 
+import java.util.concurrent.atomic.AtomicBoolean;
+
 import static io.jooby.StatusCode.NO_CONTENT;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.mockito.Mockito.mock;
@@ -116,4 +118,5 @@ public void mvcApp() {
     MockRouter router = new MockRouter(new MvcApp());
     assertEquals("/mvc", router.get("/mvc").value());
   }
+
 }