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	@title Writing Unit Tests			@title Writing Unit Tests
	@group developer			@group developer

	Simple guide to Arcanist and Phabricator unit tests.			Simple guide to Arcanist and Phorge unit tests.

	= Overview =			= Overview =

	Arcanist and Phabricator provide and use a simple unit test framework. This			Arcanist and Phorge provide and use a simple unit test framework. This
	document is aimed at project contributors and describes how to use it to add			document is aimed at project contributors and describes how to use it to add
	and run tests in these projects or other libphutil libraries.			and run tests in these projects or other libphutil libraries.

	In the general case, you can integrate `arc` with a custom unit test engine			In the general case, you can integrate `arc` with a custom unit test engine
	(like PHPUnit or any other unit testing library) to run tests in other projects.			(like PHPUnit or any other unit testing library) to run tests in other projects.
	See @{article:Arcanist User Guide: Customizing Lint, Unit Tests and Workflows}			See @{article:Arcanist User Guide: Customizing Lint, Unit Tests and Workflows}
	for information on customizing engines.			for information on customizing engines.

	= Adding Tests =			= Adding Tests =

	To add new tests to a Arcanist or Phabricator module:			To add new tests to a Arcanist or Phorge module:

	- Create a `__tests__/` directory in the module if it doesn't exist yet.			- Create a `__tests__/` directory in the module if it doesn't exist yet.
	- Add classes to the `__tests__/` directory which extend from			- Add classes to the `__tests__/` directory which extend from
	@{class:PhabricatorTestCase} (in Phabricator) or			@{class:PhabricatorTestCase} (in Phorge) or
	@{class@arcanist:PhutilTestCase} (elsewhere).			@{class@arcanist:PhutilTestCase} (elsewhere).
	- Run `arc liberate` on the library root so your classes are loadable.			- Run `arc liberate` on the library root so your classes are loadable.

	= Running Tests =			= Running Tests =

	Once you've added test classes, you can run them with:			Once you've added test classes, you can run them with:

	- `arc unit path/to/module/`, to explicitly run module tests.			- `arc unit path/to/module/`, to explicitly run module tests.
	- `arc unit`, to run tests for all modules affected by changes in the			- `arc unit`, to run tests for all modules affected by changes in the
	working copy.			working copy.
	- `arc diff` will also run `arc unit` for you.			- `arc diff` will also run `arc unit` for you.

	= Example Test Case =			= Example Test Case =

	Here's a simple example test:			Here's a simple example test:

	lang=php			lang=php
	class PhabricatorTrivialTestCase extends PhabricatorTestCase {			class PhorgeTrivialTestCase extends PhabricatorTestCase {

	private $two;			private $two;

	public function willRunOneTest($test_name) {			public function willRunOneTest($test_name) {
	// You can execute setup steps which will run before each test in this			// You can execute setup steps which will run before each test in this
	// method.			// method.
	$this->two = 2;			$this->two = 2;
	}			}

	public function testAllIsRightWithTheWorld() {			public function testAllIsRightWithTheWorld() {
	$this->assertEqual(4, $this->two + $this->two, '2 + 2 = 4');			$this->assertEqual(4, $this->two + $this->two, '2 + 2 = 4');
	}			}

	}			}

	You can see this class at @{class:PhabricatorTrivialTestCase} and run it with:			You can see this class at @{class:PhabricatorTrivialTestCase} and run it with:

	phabricator/ $ arc unit src/infrastructure/testing/testcase/			phorge/ $ arc unit src/infrastructure/testing/testcase/
	PASS <1ms* testAllIsRightWithTheWorld			PASS <1ms* testAllIsRightWithTheWorld

	For more information on writing tests, see			For more information on writing tests, see
	@{class@arcanist:PhutilTestCase} and @{class:PhabricatorTestCase}.			@{class@arcanist:PhutilTestCase} and @{class:PhabricatorTestCase}.

	= Database Isolation =			= Database Isolation =

	By default, Phabricator isolates unit tests from the database. It makes a crude			By default, Phorge isolates unit tests from the database. It makes a crude
	effort to simulate some side effects (principally, ID assignment on insert), but			effort to simulate some side effects (principally, ID assignment on insert), but
	any queries which read data will fail to select any rows and throw an exception			any queries which read data will fail to select any rows and throw an exception
	about isolation. In general, isolation is good, but this can make certain types			about isolation. In general, isolation is good, but this can make certain types
	of tests difficult to write. When you encounter issues, you can deal with them			of tests difficult to write. When you encounter issues, you can deal with them
	in a number of ways. From best to worst:			in a number of ways. From best to worst:

	- Encounter no issues; your tests are fast and isolated.			- Encounter no issues; your tests are fast and isolated.
	- Add more simulated side effects if you encounter minor issues and simulation			- Add more simulated side effects if you encounter minor issues and simulation
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