How to fix java.lang.IllegalStateException: You have not started an Objectify context

0
votes

I am trying to take a test driven development approach to building a Java based app running on App Engine, but I am having difficulties getting the setup working.

My servlet

package mobi.grocerymonkey.groceryapp;

import com.google.appengine.api.utils.SystemProperty;

import java.io.IOException;
import java.io.BufferedReader;
import java.util.Properties;

import org.json.JSONObject;
import java.util.logging.Logger;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;

import static com.googlecode.objectify.ObjectifyService.ofy;
import com.googlecode.objectify.ObjectifyService;

/* This is the servlet */
@WebServlet(name = "GroceryServlet", value = "/grocery")
public class GroceryServlet extends HttpServlet {

  private static final Logger log = Logger.getLogger(GroceryServlet.class.getName());

  @Override
  public void init() throws ServletException {
    log.info("context init");
    ObjectifyService.init();
    ObjectifyService.register(Grocery.class);
  }

  @Override
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws IOException {

    response.setContentType("text/plain");
    response.getWriter().println("Hello Kitty");
  }

  @Override
  public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws IOException {
      BufferedReader reader = request.getReader();
      String line = null;
      StringBuffer stringBuffer = new StringBuffer();
      while((line = reader.readLine()) != null) {
        stringBuffer.append(line);
      }
      String jsonString = stringBuffer.toString();
      JSONObject json = new JSONObject(jsonString);
      log.info("JSON "+ jsonString);

      Grocery grocery = new Grocery();
      grocery.setName((String) json.get("name"));
      grocery.setQuantity((Integer) json.get("quantity"));

      ofy().save().entity(grocery).now();

      log.info("JSON name "+ grocery.getName());

      response.setContentType("application/json");
      response.getWriter().println(jsonString);
    }

}

web.xml file

<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
         http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1">
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
  </welcome-file-list>
  <filter>
    <filter-name>ObjectifyFilter</filter-name>
    <filter-class>com.googlecode.objectify.ObjectifyFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>ObjectifyFilter</filter-name>
    <url-pattern>/*</url-pattern>
    <dispatcher>REQUEST</dispatcher>
    <dispatcher>INCLUDE</dispatcher>
    <dispatcher>FORWARD</dispatcher>
  </filter-mapping>
</web-app>

My unit test

package mobi.grocerymonkey.groceryapp;

import static com.google.common.truth.Truth.assertThat;
import static org.mockito.Mockito.when;
import static org.mockito.Mockito.mock;

import com.google.appengine.tools.development.testing.LocalServiceTestHelper;
import com.google.appengine.tools.development.testing.LocalDatastoreServiceTestConfig;
import com.google.cloud.datastore.DatastoreOptions;

import com.google.cloud.datastore.DatastoreOptions;
import com.googlecode.objectify.ObjectifyFactory;
import com.googlecode.objectify.ObjectifyService;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.json.JSONObject;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.BufferedReader;
import java.io.StringReader;
import java.io.Reader;
import java.io.Closeable;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Unit tests for {@link HelloAppEngine}.
 */
@RunWith(JUnit4.class)
public class GroceryServletTest {
  private static final String MOCK_URL = "/grocery";
  // Set up a helper so that the ApiProxy returns a valid environment for local testing.
  private final LocalServiceTestHelper helper =
    new LocalServiceTestHelper(new LocalDatastoreServiceTestConfig());
  private Closeable closeable;

  @Mock
  private HttpServletRequest mockRequest;

  @Mock
  private HttpServletResponse mockResponse;

  private StringWriter responseWriter;
  private GroceryServlet servletUnderTest;

  @Before
  public void setUp() throws Exception {
    MockitoAnnotations.initMocks(this);
    helper.setUp();

    ObjectifyService.init(new ObjectifyFactory(
      DatastoreOptions.newBuilder()
        .setHost("http://localhost:8081")
        .setProjectId("enduring-trees-259812")
        .build()
        .getService()
      ));
      closeable = ObjectifyService.begin();

    //  Set up some fake HTTP requests
    when(mockRequest.getRequestURI()).thenReturn(MOCK_URL);

    JSONObject grocery = new JSONObject();
    grocery.put("name", "Beer");

    Reader inputString = new StringReader(grocery.toString());
    BufferedReader reader = new BufferedReader(inputString);
    when(mockRequest.getReader()).thenReturn(reader);

    // Set up a fake HTTP response.
    responseWriter = new StringWriter();
    when(mockResponse.getWriter()).thenReturn(new PrintWriter(responseWriter));

    servletUnderTest = new GroceryServlet();
    servletUnderTest.init();
  }

  @After public void tearDown() throws Exception {
    closeable.close();
    helper.tearDown();
  }

  @Test
  public void doGetWritesResponse() throws Exception {
    servletUnderTest.doGet(mockRequest, mockResponse);

    // We expect our hello world response.
    assertThat(responseWriter.toString())
        .contains("Hello Kitty");
  }

  @Test
  public void doPostWritesResponse() throws Exception {
    JSONObject reqObj = new JSONObject();
    reqObj.put("name", "Beer");
    reqObj.put("quantity", 5);
    StringReader reader = new StringReader(reqObj.toString());

    when(mockRequest.getReader()).thenReturn(new BufferedReader(new StringReader(reqObj.toString())));

    servletUnderTest.doPost(mockRequest, mockResponse);

    // We expect our hello world response.
    assertThat(responseWriter.toString())
        .contains(reqObj.getString("name"));
  }
}

The test fails with the following error message

[ERROR] Tests run: 2, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.103 s <<< FAILURE! - in mobi.grocerymonkey.groceryapp.GroceryServletTest [ERROR] doPostWritesResponse(mobi.grocerymonkey.groceryapp.GroceryServletTest) Time elapsed: 0.078 s <<< ERROR! java.lang.IllegalStateException: You have not started an Objectify context. You are probably missing the ObjectifyFilter. If you are not running in the context of an http request, see the ObjectifyService.run() method. at mobi.grocerymonkey.groceryapp.GroceryServletTest.doPostWritesResponse(GroceryServletTest.java:109)

which is caused by this line ofy().save().entity(grocery).now() in my servlet. When I remove it, the test is run without errors.

I have tried to follow different approaches to resolve this error found here on stackoverflow but without luck.

How should the test/app be setup to be able to develop it using a test driven approach? What I am looking for is a way to be able to write the unit test first and then the actual application. But how to succeed?

(Disclaimer, I haven't worked with Java in over a decade)

UPDATE

ServletContext file

package mobi.grocerymonkey.groceryapp;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

import java.io.Closeable;
import java.io.IOException;

import com.googlecode.objectify.ObjectifyService;
import static com.googlecode.objectify.ObjectifyService.ofy;

@WebListener
public class GroceryContextListener implements ServletContextListener {

    private ServletContext context;
    private Closeable closeable;

    public void contextInitialized(ServletContextEvent event) {
        this.context = event.getServletContext();

        ObjectifyService.init();
        this.closeable = ObjectifyService.begin();
        ObjectifyService.register(Grocery.class);
        System.out.println("Context initialized");
    }

    public void contextDestroyed(ServletContextEvent event) {
      try {
        this.closeable.close();
      } catch(IOException ioe) {

      }
    }
}

Unittest file

package mobi.grocerymonkey.groceryapp;

import static com.google.common.truth.Truth.assertThat;
import static org.mockito.Mockito.when;
import static org.mockito.Mockito.mock;

import com.google.appengine.tools.development.testing.LocalServiceTestHelper;
import com.google.appengine.tools.development.testing.LocalDatastoreServiceTestConfig;
import com.google.cloud.datastore.DatastoreOptions;

import com.google.cloud.datastore.DatastoreOptions;
import com.googlecode.objectify.ObjectifyFactory;
import com.googlecode.objectify.ObjectifyService;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.json.JSONObject;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.BufferedReader;
import java.io.StringReader;
import java.io.Reader;
import java.io.Closeable;
import java.io.IOException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletContextEvent;

/**
 * Unit tests for {@link HelloAppEngine}.
 */
@RunWith(JUnit4.class)
public class GroceryServletTest {
  private static final String MOCK_URL = "/grocery";
  // Set up a helper so that the ApiProxy returns a valid environment for local testing.
  private final LocalServiceTestHelper helper =
    new LocalServiceTestHelper(new LocalDatastoreServiceTestConfig());
  private Closeable closeable;

  @Mock
  private HttpServletRequest mockRequest;

  @Mock
  private HttpServletResponse mockResponse;

  private ServletContextListener contextListener;
  private ServletContext context;

  private StringWriter responseWriter;
  private GroceryServlet servletUnderTest;

  @Before
  public void setUp() throws Exception {
    MockitoAnnotations.initMocks(this);
    helper.setUp();

    contextListener = new GroceryContextListener();
    context = mock(ServletContext.class);

    //  Set up some fake HTTP requests
    when(mockRequest.getRequestURI()).thenReturn(MOCK_URL);

    JSONObject grocery = new JSONObject();
    grocery.put("name", "Beer");

    Reader inputString = new StringReader(grocery.toString());
    BufferedReader reader = new BufferedReader(inputString);
    when(mockRequest.getReader()).thenReturn(reader);

    // when(mockRequest.getServletContext()).thenReturn(context);

    // Set up a fake HTTP response.
    responseWriter = new StringWriter();
    when(mockResponse.getWriter()).thenReturn(new PrintWriter(responseWriter));

    servletUnderTest = new GroceryServlet();
  }

  @After 
  public void tearDown() throws Exception {
    helper.tearDown();
  }

  @Test
  public void doGetWritesResponse() throws Exception {
    servletUnderTest.doGet(mockRequest, mockResponse);

    // We expect our hello world response.
    assertThat(responseWriter.toString())
        .contains("Hello Kitty");
  }

  @Test
  public void doPostWritesResponse() throws Exception {
    contextListener.contextInitialized(new ServletContextEvent(context));

    JSONObject reqObj = new JSONObject();
    reqObj.put("name", "Beer");
    reqObj.put("quantity", 5);
    StringReader reader = new StringReader(reqObj.toString());

    when(mockRequest.getReader()).thenReturn(new BufferedReader(new StringReader(reqObj.toString())));

    servletUnderTest.doPost(mockRequest, mockResponse);

    // We expect our hello world response.
    assertThat(responseWriter.toString())
        .contains(reqObj.getString("name"));
  }
}

Servlet file

package mobi.grocerymonkey.groceryapp;

import com.google.appengine.api.utils.SystemProperty;

import java.io.IOException;
import java.io.BufferedReader;
import java.util.Properties;

import org.json.JSONObject;
import java.util.logging.Logger;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;

import static com.googlecode.objectify.ObjectifyService.ofy;
import com.googlecode.objectify.ObjectifyService;

/* This is the servlet */
@WebServlet(name = "GroceryServlet", value = "/grocery")
public class GroceryServlet extends HttpServlet {

  private static final Logger log = Logger.getLogger(GroceryServlet.class.getName());

  @Override
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws IOException {

    response.setContentType("text/plain");
    response.getWriter().println("Hello Kitty");
  }

  @Override
  public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws IOException {
      BufferedReader reader = request.getReader();
      String line = null;
      StringBuffer stringBuffer = new StringBuffer();
      while((line = reader.readLine()) != null) {
        stringBuffer.append(line);
      }
      String jsonString = stringBuffer.toString();
      JSONObject json = new JSONObject(jsonString);
      log.info("JSON "+ jsonString);

      Grocery grocery = new Grocery();
      grocery.setName((String) json.get("name"));
      grocery.setQuantity((Integer) json.get("quantity"));

      ofy().save().entity(grocery).now();

      log.info("JSON name "+ grocery.getName());

      response.setContentType("application/json");
      response.getWriter().println(jsonString);
    }

}

Now I am getting a "com.google.cloud.datastore.DatastoreException: Unauthenticated" error when running the test, so looks like I am on the right way. Would I store the datastore credentials in the web.xml and then pass them to the context similar to 

ObjectifyService.init(new ObjectifyFactory(
      DatastoreOptions.newBuilder()
        .setHost("http://localhost:8081")
        .setProjectId("enduring-trees-259812")
        .build()
        .getService()
      ));
    ObjectifyService.factory().register(Grocery.class);

New Update

I upgraded to Junit5 and rewrote the entire test to this

package mobi.grocerymonkey.groceryapp;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.AfterAll;
import static org.junit.jupiter.api.Assertions.assertEquals;

import com.googlecode.objectify.ObjectifyFactory;
import com.googlecode.objectify.ObjectifyService;
import com.googlecode.objectify.util.Closeable;
import static com.googlecode.objectify.ObjectifyService.factory;
import static com.googlecode.objectify.ObjectifyService.ofy;
import com.googlecode.objectify.Key;

import com.google.cloud.datastore.Datastore;
import com.google.cloud.datastore.DatastoreOptions;
import com.google.cloud.datastore.testing.LocalDatastoreHelper;
import com.google.appengine.api.datastore.DatastoreService;
import com.google.appengine.api.datastore.DatastoreServiceFactory;
import com.google.appengine.tools.development.testing.LocalDatastoreServiceTestConfig;
import com.google.appengine.tools.development.testing.LocalServiceTestHelper;

import mobi.grocerymonkey.groceryapp.util.TestBase;

import mobi.grocerymonkey.groceryapp.domain.Grocery;
import mobi.grocerymonkey.groceryapp.domain.GroceryList;

public class MyFirstTest extends TestBase {

  // Maximum eventual consistency.
  private final static LocalServiceTestHelper helper =
      new LocalServiceTestHelper(new LocalDatastoreServiceTestConfig()
          .setDefaultHighRepJobPolicyUnappliedJobPercentage(100));

  Closeable closeable;

  @BeforeAll
  public static void setUp() {
    helper.setUp();
  }

  @AfterAll
  public static void tearDown() {
    helper.tearDown();
  }

  @BeforeEach
  public void setUpEach() {
    ObjectifyService.init(new ObjectifyFactory(
      DatastoreOptions.getDefaultInstance().getService()));
    closeable = ObjectifyService.begin();
  }

  @AfterEach
  public void tearDownEach() {
    closeable.close();
  }

  @DisplayName("Test MyFirstTest.testAddition()")
  @Test
  public void testAddition() {
    assertEquals(1 + 1, 2);
  }

  @DisplayName("Testing testGroceryList()")
  @Test
  public void testGroceryList() {
    factory().register(GroceryList.class);

    GroceryList list = new GroceryList("Weekend Beer List");
    Key<GroceryList> k1 = ofy().save().entity(list).now();

    assertEquals(1+1, 2);
  }
}

It is deliberately kept in a single file for now. But for some reason, the datastore cannot find the emulator that is running when the test is run. I am getting a Datastore Unauthenticated error.

I ran gcloud beta emulators datastore start and $(gcloud beta emulators datastore env-init) before running the unit test.

2
javagoogle-app-engineservletsjunitobjectify

2 Answers

0
votes

The core of test-driven development revolves around five steps, which you repeated throughout the software development life cycle.

Test-driven development life-cycle:

  1. Write the test

  2. Run the test (without implementation code, test does not pass)

  3. Write just enough implementation so the test passes

  4. Run all tests (test pass)

  5. Refactor

  6. Repeat

By following this steps you can create a TDD implementation for your application.

There is no specific way for Google Cloud to do beside the steps I have specified above.

As specified in your error, you can see that you have not started an Objectify context, and you are missing the ObjectifyFilter.

Here is a implementation of a list in Java, which follows the TDD, which may be helpful to clear some of your concerns.

0
votes

The problem is that you're calling ObjectifyService.init() twice, but you only called begin() on the first (abandoned) factory.

You call init() in your setUp() method, which initializes the static ObjectifyFactory. You then open a session on that factory with the ObjectifyService.begin() call.

At the end of your setUp() you call servletUnderTest.init(), which also calls ObjectifyService.init(). This replaces the static ObjectifyFactory. When you next execute your servlet and call ofy()..., you're using a factory that has not started a session.

Take a look at the code for ObjectifyService. It's quite literally just a few lines of code to wrap a static ObjectifyFactory instance.

If you have more than one servlet, this code will not work well in production either - you only want to initialize and register your classes once. I recommend doing this with a ServletContextListener.