How to pass the web driver instance from one testcase class to another testcase class in TestNG?

Question

InitializeDriver.java:

public class InitializeDriver{

WebDriver driver;

public WebDriver getDriver() throws Exception{
        driver = new FirefoxDriver();
        System.out.println("Initialize Browser: Browser is initalized");
        return driver;
}

@BeforeSuite
public static void openBrowser() {
    driver.get("blah.blah.blah"));
    driver.manage().window().maximize();
    driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
    System.out.println("openBrowser: Browser is opened");
}

@AfterSuite
public static void closeBrowser() {
    driver.quit();
    System.out.println("closeBrowser: Browser is closed");
    }
 }

I have two testcase files.
1) testcase1.java
2) testcase2.java

testing.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="TestSuite">
    <test thread-count="5" name="Test">
        <classes>
            <class name="InitializeDriver" />
            <class name="Testcase1" />
            <class name="Testcase2" />
        </classes>
    </test> <!-- Test -->
</suite> <!-- Suite -->

Testcase1.java:

  public class Testcase1 {
    WebDriver driver = InitializeDriver.getDriver();
    //some operations
    .....
    .....
    Testcase2 tc2=new Testcase2(driver);
}

Testcase2.java

public class Testcase2 {
    //some operations
    .....
    .....
}

The Output is:

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running TestSuite
1540192536684   mozrunner::runner   INFO    Running command: "C:\\Program Files\\Mozilla Firefox\\firefox.exe" "-marionette" "-foreground" "-no-remote" "-profile" "C:\\Users\\sample\\AppData\\Local\\Temp\\rust_mozprofile.VgaP2iQZZRM1"
1540192539830   Marionette  INFO    Listening on port 54439
1540192540037   Marionette  WARN    TLS certificate errors will be ignored for this session
1540192540101   Marionette  DEBUG   [6442450945] Frame script loaded
1540192540127   Marionette  DEBUG   [6442450945] Frame script registered
Oct 22, 2018 12:45:40 PM org.openqa.selenium.remote.ProtocolHandshake createSession
INFO: Detected dialect: W3C

Initialize Browser: Browser is initalized

1540192540526   Marionette  DEBUG   [6442450945] Received DOM event beforeunload for about:blank
1540192541179   Marionette  DEBUG   [6442450945] Received DOM event pagehide for about:blank
1540192543731   Marionette  DEBUG   [6442450945] Received DOM event DOMContentLoaded for blah.blah.blah
1540192544033   Marionette  DEBUG   [6442450945] Received DOM event pageshow for blah.blah.blah

openBrowser: Browser is opened
Inside Test Case 1

1540192561608   Marionette  INFO    Stopped listening on port 54439
[Parent 18364, Gecko_IOThread] WARNING: pipe error: 109: file z:/build/build/src/ipc/chromium/src/chrome/common/ipc_channel_win.cc, line 346
[Child 3432, Chrome_ChildThread] WARNING: pipe error: 109: file z:/build/build/src/ipc/chromium/src/chrome/common/ipc_channel_win.cc, line 346
[Child 3432, Chrome_ChildThread] WARNING: pipe error: 109: file z:/build/build/src/ipc/chromium/src/chrome/common/ipc_channel_win.cc, line 346
[Parent 18364, Gecko_IOThread] WARNING: pipe error: 109: file z:/build/build/src/ipc/chromium/src/chrome/common/ipc_channel_win.cc, line 346
[Parent 18364, Gecko_IOThread] WARNING: pipe error: 109: file z:/build/build/src/ipc/chromium/src/chrome/common/ipc_channel_win.cc, line 346
[GPU 4372, Chrome_ChildThread] WARNING: pipe error: 109: file z:/build/build/src/ipc/chromium/src/chrome/common/ipc_channel_win.cc, line 346

###!!! [Child][MessageChannel::SendAndWait] Error: Channel error: cannot send/recv

closeBrowser: Browser is closed
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 29.642 sec

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 33.065 s
[INFO] Finished at: 2018-10-22T12:46:04+05:30
[INFO] Final Memory: 10M/243M
[INFO] ------------------------------------------------------------------------

It tests only the Testcase1.java and not the testcase2.java.
Please help me !

Answer 1

I would suggest you to do like this, it's worked for me

InitializeDriver.java:

public class InitializeDriver{

public static WebDriver driver;

public void getDriver() throws Exception{
        driver = new FirefoxDriver();
        System.out.println("Initialize Browser: Browser is initalized");

}

@BeforeSuite
public void openBrowser() {
    driver.get("blah.blah.blah"));
    driver.manage().window().maximize();
    driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
    System.out.println("openBrowser: Browser is opened");
}

@AfterSuite
public void closeBrowser() {
    driver.quit();
    System.out.println("closeBrowser: Browser is closed");
    }
 }  

Testcase1.java:

 public class Testcase1 extends InitializeDriver {

    //some operations
    .....
    .....
}  

testing.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="TestSuite">
    <test thread-count="5" name="Test">
        <classes>

            <class name="Testcase1" />

        </classes>
    </test> <!-- Test -->
</suite> <!-- Suite -->  

It will work for your all test class

Answer 2

Here are few notes:

1. You cannot use this line WebDriver driver = InitializeDriver.getDriver(); because your getDriver() method is not static (according to your example). To call non-static methods you need to instantiate objects first.

2. I would not recommend to use the same WebDriver instance in different tests because that would make your tests dependent on each other. Since all the changed you will introduce to WebDriver object in one test will have the place in another tests which might impact the logic.

3. If you use the same driver for all your tests you should carefully use quit() and close() methods.

4. If you still need to use the same instance you may set your WebDriver as a static field of some class, initialize it once, and then just take that field when you need WebDriver in all your tests.

P.S. - If you need to force everyone to use the only single driver in all the tests and all the users of your framework, then you can implement Singleton pattern like shown below:

public class SingletonWebDriver {

    private static WebDriver driver;

    private SingletonWebDriver(){};

    public static WebDriver getDriver(){
        if (driver == null){
            driver = new ChromeDriver(); // Here you can introduce some logic on what particular driver to instantiate.
        }
        return driver;
    }
}

So having this class implemented you can use import static SingletonWebDriver to your test classes and use getDriver() instead of driver in your code.