mirror of
https://github.com/danog/psalm.git
synced 2024-12-02 09:37:59 +01:00
111 lines
2.4 KiB
Markdown
111 lines
2.4 KiB
Markdown
# Adding assertions
|
|
|
|
Psalm has three docblock annotations that allow you to specify that a function verifies facts about variables and properties:
|
|
|
|
- `@psalm-assert` (used when throwing an exception)
|
|
- `@psalm-assert-if-true`/`@psalm-assert-if-false` (used when returning a `bool`)
|
|
|
|
A list of acceptable assertions [can be found here](assertion_syntax.md).
|
|
|
|
## Examples
|
|
|
|
If you have a class that verified its input is an array of strings, you can make that clear to Psalm:
|
|
|
|
```php
|
|
<?php
|
|
/** @psalm-assert string[] $arr */
|
|
function validateStringArray(array $arr) : void {
|
|
foreach ($arr as $s) {
|
|
if (!is_string($s)) {
|
|
throw new UnexpectedValueException('Invalid value ' . gettype($s));
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
This enables you to call the `validateStringArray` function on some data and have Psalm understand that the given data *must* be an array of strings:
|
|
|
|
```php
|
|
<?php
|
|
function takesString(string $s) : void {}
|
|
function takesInt(int $s) : void {}
|
|
|
|
function takesArray(array $arr) : void {
|
|
takesInt($arr[0]); // this is fine
|
|
|
|
validateStringArray($arr);
|
|
|
|
takesInt($arr[0]); // this is an error
|
|
|
|
foreach ($arr as $a) {
|
|
takesString($a); // this is fine
|
|
}
|
|
}
|
|
```
|
|
|
|
Similarly, `@psalm-assert-if-true` and `@psalm-assert-if-false` will filter input if the function/method returns `true` and `false` respectively:
|
|
|
|
```php
|
|
<?php
|
|
class A {
|
|
public function isValid() : bool {
|
|
return (bool) rand(0, 1);
|
|
}
|
|
}
|
|
class B extends A {
|
|
public function bar() : void {}
|
|
}
|
|
|
|
/**
|
|
* @psalm-assert-if-true B $a
|
|
*/
|
|
function isValidB(A $a) : bool {
|
|
return $a instanceof B && $a->isValid();
|
|
}
|
|
|
|
/**
|
|
* @psalm-assert-if-false B $a
|
|
*/
|
|
function isInvalidB(A $a) : bool {
|
|
return $a instanceof B || !$a->isValid();
|
|
}
|
|
|
|
function takesA(A $a) : void {
|
|
if (isValidB($a)) {
|
|
$a->bar();
|
|
}
|
|
|
|
if (isInvalidB($a)) {
|
|
// do something
|
|
} else {
|
|
$a->bar();
|
|
}
|
|
|
|
$a->bar(); //error
|
|
}
|
|
```
|
|
|
|
As well as getting Psalm to understand that the given data must be a certain type, you can also show that a variable must be not null:
|
|
|
|
```php
|
|
<?php
|
|
/**
|
|
* @psalm-assert !null $value
|
|
*/
|
|
function assertNotNull($value): void {
|
|
// Some check that will mean the method will only complete if $value is not null.
|
|
}
|
|
```
|
|
|
|
And you can check on null values:
|
|
|
|
```php
|
|
<?php
|
|
/**
|
|
* @psalm-assert-if-true null $value
|
|
*/
|
|
function isNull($value): bool {
|
|
return ($value === null);
|
|
}
|
|
```
|