KyleWpppd KyleWpppd -4 years ago 61
PHP Question

Distinguish between NULL and FALSE with PHPUnit

Does anyone know a reliable way to distinguish between FALSE and NULL with PHPUnit?

I'm trying to distinguish from NULL and FALSE in return values in my assertions.

This fails:

$this->assertNotEquals(FALSE, NULL);

And these assertions pass:


Edit: For some context, this is to distinguish between an error state (FALSE) versus an empty result (NULL). To ensure the function is returning properly, I need to distinguish between the two.

As per some of the problems regarding what I am testing, I'm adding the tests.

Class testNullFalse extends PHPUnit_Framework_TestCase{

public function test_null_not_false (){
$this->assertNotEquals(FALSE, NULL, "False and null are not the same");

public function test_null_is_false (){
$this->assertFalse(NULL, "Null is clearly not FALSE");

public function test_false_is_null (){
$this->assertNull(FALSE, "False is clearly not NULL");

public function test_false_equals_null(){
$this->assertEquals(FALSE, NULL, "False and null are not equal");

public function test_false_sameas_null(){
$this->assertSame(FALSE, NULL, "False and null are not the same");

public function test_false_not_sameas_null(){
$this->assertNotSame(FALSE, NULL, "False and null are not the same");

And the results.

PHPUnit 3.5.10 by Sebastian Bergmann.


Time: 0 seconds, Memory: 5.50Mb

There were 4 failures:

1) testNullFalse::test_null_not_false
False and null are not the same
Failed asserting that <null> is not equal to <boolean:false>.

2) testNullFalse::test_null_is_false
Null is clearly not FALSE
Failed asserting that <null> is false.

3) testNullFalse::test_false_is_null
False is clearly not NULL
Failed asserting that <boolean:false> is null.

4) testNullFalse::test_false_sameas_null
False and null are not the same
<null> does not match expected type "boolean".

Tests: 6, Assertions: 6, Failures: 4.

Answer Source

These assertions use == which will perform type coercion. Hamcrest has identicalTo($value) which uses ===, and I believe PHPUnit has assertSame($expected, $actual) which does the same.

self::assertSame(false, $dao->getUser(-2));

Update: In answer to your comment, "It can be NULL or an object":

$user = $dao->getUser(-2);
self::assertTrue($user === null || is_object($user));

Using Hamcrest assertions is a little more expressive, especially in the event of a failure:

assertThat($dao->getUser(-2), anyOf(objectValue(), nullValue()));
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