If tests are ran from an already installed Piwik, it should configure everything automatically and just work from what I remember. Can you check if you have a section [database_tests] in your config/config.ini.php as described here? https://github.com/piwik/piwik/tree/master/tests#phpunit-tests

Mine looks like this:

[database_tests]
host = "127.0.0.1"
username = "root"
password = "secure"
tables_prefix = ""

I don't think the empty tables_prefix entry is required but maybe it helps

I tried running the tests using your way but I am not able to run the Integration tests. Unit Tests ran fine. Please note that I reinstalled Piwik from scratch as well. I am getting the below error log now -

61. Piwik\Plugins\UsersManager\tests\Integration\UsersManagerTest
    Failed to setup fixture: TEST INITIALIZATION FAILED: Trying to drop original database 'workspace'. Something's wrong w/ the tests.
    #0 C:\xampp\htdocs\PHPStorm\tests\PHPUnit\Framework\Fixture.php(227): Piwik\Tests\Framework\Fixture->dropDatabase()
    adding support for windows phone 7 version 7.5 #1 C:\xampp\htdocs\PHPStorm\tests\PHPUnit\Framework\TestCase\SystemTestCase.php(76): Piwik\Tests\Framework\Fixture->performSetUp()
    Using alternate database. #2 C:\xampp\htdocs\PHPStorm\tests\PHPUnit\Framework\TestCase\IntegrationTestCase.php(61): Piwik\Tests\Framework\TestCase\SystemTestCase::setUpBeforeClass()
    Updates ? #3 [internal function]: Piwik\Tests\Framework\TestCase\IntegrationTestCase::setUpBeforeClass()
    SitesManager plugins: added group managment to admin UI #4 C:\xampp\htdocs\PHPStorm\vendor\phpunit\phpunit\src\Framework\TestSuite.php(697): call_user_func(Array)
    Collaboration via github #5 C:\xampp\htdocs\PHPStorm\vendor\phpunit\phpunit\src\TextUI\TestRunner.php(440): PHPUnit_Framework_TestSuite->run(Object(PHPUnit_Framework_TestResult))
    [#3316] Add request parameter option to disable seriesPicker on jqplot #6 C:\xampp\htdocs\PHPStorm\vendor\phpunit\phpunit\src\TextUI\Command.php(149): PHPUnit_TextUI_TestRunner->doRun(Object(PHPUnit_Framework_TestSuite), Array)
    [#3341] Add possibility to pass custom plot properties in request eg. canvasLegend #7 C:\xampp\htdocs\PHPStorm\vendor\phpunit\phpunit\src\TextUI\Command.php(100): PHPUnit_TextUI_Command->run(Array, true)
    [#3317] export_as_image_icon setting has no effect on widget #8 C:\xampp\htdocs\PHPStorm\vendor\phpunit\phpunit\phpunit(47): PHPUnit_TextUI_Command::main()
    [#3327] Add show_related_reports request parameter #9 {main}
    #0 C:\xampp\htdocs\PHPStorm\tests\PHPUnit\Framework\Fixture.php(245): PHPUnit_Framework_Assert::fail('TEST INITIALIZA...')
    adding support for windows phone 7 version 7.5 #1 C:\xampp\htdocs\PHPStorm\tests\PHPUnit\Framework\TestCase\SystemTestCase.php(76): Piwik\Tests\Framework\Fixture->performSetUp()
    Using alternate database. #2 C:\xampp\htdocs\PHPStorm\tests\PHPUnit\Framework\TestCase\IntegrationTestCase.php(61): Piwik\Tests\Framework\TestCase\SystemTestCase::setUpBeforeClass()
    Updates ? #3 [internal function]: Piwik\Tests\Framework\TestCase\IntegrationTestCase::setUpBeforeClass()
    SitesManager plugins: added group managment to admin UI #4 C:\xampp\htdocs\PHPStorm\vendor\phpunit\phpunit\src\Framework\TestSuite.php(697): call_user_func(Array)
    Collaboration via github #5 C:\xampp\htdocs\PHPStorm\vendor\phpunit\phpunit\src\TextUI\TestRunner.php(440): PHPUnit_Framework_TestSuite->run(Object(PHPUnit_Framework_TestResult))
    [#3316] Add request parameter option to disable seriesPicker on jqplot #6 C:\xampp\htdocs\PHPStorm\vendor\phpunit\phpunit\src\TextUI\Command.php(149): PHPUnit_TextUI_TestRunner->doRun(Object(PHPUnit_Framework_TestSuite), Array)
    [#3341] Add possibility to pass custom plot properties in request eg. canvasLegend #7 C:\xampp\htdocs\PHPStorm\vendor\phpunit\phpunit\src\TextUI\Command.php(100): PHPUnit_TextUI_Command->run(Array, true)
    [#3317] export_as_image_icon setting has no effect on widget #8 C:\xampp\htdocs\PHPStorm\vendor\phpunit\phpunit\phpunit(47): PHPUnit_TextUI_Command::main()
    [#3327] Add show_related_reports request parameter #9 {main}

C:\xampp\htdocs\PHPStorm\tests\PHPUnit\Framework\TestCase\SystemTestCase.php:78
C:\xampp\htdocs\PHPStorm\tests\PHPUnit\Framework\TestCase\IntegrationTestCase.php:61

FAILURES!
Tests: 3721, Assertions: 0, Errors: 61.

Does the MySQL user maybe not have enough permission eg to drop a database or so?

@tsteur - I checked the permissions and everything is setup correctly. Since this is my personal dev machine, the database user has got every permission listed.

Today I have experienced the same problem! so there is something buggy (at least in 2.x-dev branch). Not found the solution so far.
my config.ini.php has:

[database_tests]
host = "127.0.0.1"
username = "root"
password = ""
dbname = piwik_tests
tables_prefix = piwiktests_

(changing tables_prefix does not help)

output:

$ ./console tests:run
Executing command: cd /home/matt/dev/piwik-2.x-dev/tests/PHPUnit && /home/matt/dev/piwik-2.x-dev/vendor/bin/phpunit   --testsuite UnitTests
PHP Fatal error:  Uncaught PDOException: SQLSTATE[42S02]: Base table or view not found: 1146 Table 'piwik_tests.piwiktests_option' doesn't exist in /home/matt/dev/piwik-2.x-dev/libs/Zend/Db/Statement/Pdo.php:228
Stack trace:
#0 /home/matt/dev/piwik-2.x-dev/libs/Zend/Db/Statement/Pdo.php(228): PDOStatement->execute(Array)
#1 /home/matt/dev/piwik-2.x-dev/libs/Zend/Db/Statement.php(300): Zend_Db_Statement_Pdo->_execute(Array)
#2 /home/matt/dev/piwik-2.x-dev/libs/Zend/Db/Adapter/Abstract.php(479): Zend_Db_Statement->execute(Array)
#3 /home/matt/dev/piwik-2.x-dev/libs/Zend/Db/Adapter/Pdo/Abstract.php(238): Zend_Db_Adapter_Abstract->query('SELECT option_v...', Array)
#4 /home/matt/dev/piwik-2.x-dev/core/Db/Adapter/Pdo/Mysql.php(245): Zend_Db_Adapter_Pdo_Abstract->query('SELECT option_v...', Array)
#5 /home/matt/dev/piwik-2.x-dev/libs/Zend/Db/Adapter/Abstract.php(736): Piwik\Db\Adapter\Pdo\Mysql->query('SELECT option_v...', Array)
#6 /home/matt/dev/piwik-2.x-dev/core/Db.php(217): Zend_Db_Adapter_Abstract->fetchAll('SELECT option_v... in /home/matt/dev/piwik-2.x-dev/libs/Zend/Db/Statement/Pdo.php on line 234

Found the solution for me, as my piwik is installed in a sub-directory (at localhost/piwik-2.x-dev), it's required to set:

[tests]
request_uri = "/piwik-2.x-dev/"

we need to improve this and document it better both on: https://developer.piwik.org/guides/getting-started-part-1 and in the console command output

I had the same trouble trying to set up tests at 3.0.2. In particular, I was getting a handful of errors which I'll reproduce below so folks googling can find them.

When following the instructions verbatim, I got this error trying to run unit tests

PHP Fatal error:  Uncaught PDOException: SQLSTATE[HY000] [1045] Access denied for user '@USERNAME@'@'localhost' (using password: YES) in /piwik/piwik/libs/Zend/Db/Adapter/Pdo/Abstract.php:128

When, in the course of experimenting, I tried changing user to username, I got a different error:

PHP Fatal error:  Uncaught PDOException: SQLSTATE[42S02]: Base table or view not found: 1146 Table 'piwik_tests.piwiktests_option' doesn't exist in /media/sf_bkassembly-piwik/piwik/libs/Zend/Db/Statement/Pdo.php:228

To solve this, I copied a section from global.ini.php into config.ini.php and filled in appropriate values:

[database_tests]
host = localhost
username = "root"
password = "root"
dbname = piwik_tests
tables_prefix = piwiktests_
port = 3306
adapter = PDO\MYSQL
type = InnoDB
schema = Mysql
charset = utf8

[tests]
; needed in order to run tests.
; if Piwik is available at http://localhost/dev/piwik/ replace @REQUEST_URI@ with /dev/piwik/
; note: the REQUEST_URI should not contain "plugins" or "tests" in the PATH
http_host   = localhost
remote_addr = "127.0.0.1"
request_uri = "/"
port = 8777             # turned out to be very important

The tests now run fine

I'd be happy to submit a patch to the docs if someone can confirm that the result I have here is roughly what the docs ought to suggest.

Thanks for posting @johnhess - a patch to the developer docs would be appreciated 👍

With Matomo 3.5.1 (from archive)

./console tests:run

does not work anymore at all:

[InvalidArgumentException]                               
There are no commands defined in the "tests" namespace.  

But the docs here still propose to execute that:
https://developer.matomo.org/guides/tests-php

@johsin18 did you run ./console development:enable?

@sgiehl development:enable did not help, but what did help was to install Matomo from the git repo (not from the archive). This is mentioned clearly in tests/README.md, but not here:
https://developer.matomo.org/guides/tests
It is proposed here
https://developer.matomo.org/guides/getting-started-part-1
but sounds more like an optional thing there, and in fact most other stuff works with the archive version as well.
Could you maybe mention in this section at least?
https://developer.matomo.org/guides/getting-started-part-1#if-you-want-to-execute-the-automated-test-suite

Created PR at matomo-org/developer-documentation#307