daily-email: add 2023-08-19

Asserting all the things

src/content/daily-email/2023-08-19.md

@@ -0,0 +1,43 @@
+---
+title: >
+  Asserting all the things
+pubDate: 2023-08-19
+permalink: >
+  archive/2023/08/19/asserting-all-the-things
+tags:
+  - php
+---
+
+As well as assertions within tests, you can also check within implementation code that things are in an expected state or contain a certain value.
+
+In PHP, this is done by throwing an Exception if a condition is met.
+
+For example:
+
+```php
+if (!is_array(false)) {
+  throw new \Exception('Not an array');
+}
+```
+
+There's also the `assert` construct which, since PHP 8.0, throws an Exception by default:
+
+```php
+assert(is_array(false));
+```
+
+You can also use an assertion library, such as `webmozart/assert` or `beberlei/assert` which provide assertions and guard methods:
+
+```php
+use Webmozart\Assert\Assert;
+
+Assert::isArray(false);
+```
+
+Similarly, if the condition fails, it throws an Exception that can be caught elsewhere.
+
+As well as basic assertions such as the item is the expected type or don't match the condition, there are more complex assertions, such as all items within an array are a certain type or that an integer is positive.
+
+## Here's the thing
+
+I use guard conditions a lot within my code. If something is not as I'd expect, I like for an error to be thrown. This makes is easy to test and to debug any failures compared to failing silently.