phpunit: How do I pass values between tests?

The setUp() method is always called before tests, so even if you set up a dependency between two tests, any variables set in setUp() will be overwritten. The way PHPUnit data passing works is from the return value of one test to the parameter of the other:

class JsonRpcBitcoinTest extends PHPUnit_Framework_TestCase
{
    public function setUp()
    {
        global $configRpcUser, $configRpcPass, $configRpcHost, $configRpcPort;

        $this->bitcoindConn = new JsonRpcBitcoin($configRpcUser, $configRpcPass, $configRpcHost, $configRpcPort);
        $this->blockHash = '';
    }


    public function testCmdGetBlockHash()
    {   
        $result = (array)json_decode($this->bitcoindConn->getblockhash(20));
        $this->assertNotNull($result['result']);

        return $result['result']; // the block hash
    }


    /**
     * @depends testCmdGetBlockHash
     */
    public function testCmdGetBlock($blockHash) // return value from above method
    {   
        $result = (array)json_decode($this->bitcoindConn->getblock($blockHash));
        $this->assertEquals($result['error'], $blockHash);
    }
}

So if you need to save more state between tests, return more data in that method. I would guess that the reason PHPUnit makes this annoying is to discourage dependent tests.

See the official documentation for details.

Another option is to use static variables.

Here is an example (for Symfony 4 functional tests):

namespace App\Tests\Controller\Api;

use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Hautelook\AliceBundle\PhpUnit\RefreshDatabaseTrait;
use Symfony\Component\HttpFoundation\AcceptHeader;

class BasicApiTest extends WebTestCase
{
    // This trait provided by HautelookAliceBundle will take care of refreshing the database content to a known state before each test
    use RefreshDatabaseTrait;

    private $client = null;

    /**
     * @var string
     */
    private const APP_TOKEN = 'token-for-tests';

    /**
     * @var string
     */
    private static $app_user__email = 'tester+api+01@localhost';

    /**
     * @var string
     */
    private static $app_user__pass = 'tester+app+01+password';

    /**
     * @var null|string
     */
    private static $app_user__access_token = null;

    public function test__Authentication__Login()
    {
        $this->client->request(
            Request::METHOD_POST,
            '/api/login',
            [],
            [],
            [
                'CONTENT_TYPE' => 'application/json',
                'HTTP_App-Token' => self::APP_TOKEN
            ],
            '{"user":"'.static::$app_user__email.'","pass":"'.static::$app_user__pass.'"}'
        );
        $response = $this->client->getResponse();

        $this->assertEquals(Response::HTTP_OK, $response->getStatusCode());

        $content_type = AcceptHeader::fromString($response->headers->get('Content-Type'));
        $this->assertTrue($content_type->has('application/json'));

        $responseData = json_decode($response->getContent(), true);
        $this->assertArrayHasKey('token', $responseData);

        $this->static = static::$app_user__access_token = $responseData['token'];
    }

    /**
     * @depends test__Authentication__Login
     */
    public function test__SomeOtherTest()
    {
        $this->client->request(
            Request::METHOD_GET,
            '/api/some_endpoint',
            [],
            [],
            [
                'CONTENT_TYPE' => 'application/json',
                'HTTP_App-Token' => self::APP_TOKEN,
                'HTTP_Authorization' => 'Bearer ' . static::$app_user__access_token
            ],
            '{"user":"'.static::$app_user__email.'","pass":"'.static::$app_user__pass.'"}'
        );
        $response = $this->client->getResponse();

        $this->assertEquals(Response::HTTP_OK, $response->getStatusCode());

        $content_type = AcceptHeader::fromString($response->headers->get('Content-Type'));
        $this->assertTrue($content_type->has('application/json'));
        //...
    }
}

You can use a static variable within a function... PHP annoyingly shares static variables of class methods with all the instances... But in this cas it can help :p

protected function &getSharedVar()
{
    static $value = null;
    return $value;
}

...

public function testTest1()
{
    $value = &$this->getSharedVar();

    $value = 'Hello Test 2';
}


public function testTest2()
{
    $value = &$this->getSharedVar();

    // $value should be ok
}

NB: this is NOT the good way but it helps if you need some data in all your tests...