Add daily email for 2024-02-20

Which level is right for you?

source/_daily_emails/2024-02-20.md

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+---
+title: Which level is right for you?
+date: 2024-02-20
+permalink: archive/2024/02/20/which-level-is-right-for-you
+snippet: |
+    TODO
+tags:
+    - software-development
+    - static-analysis
+    - php
+    - phpstan
+---
+
+Today, whilst working on [Versa], I was experimenting with different PHPStan levels.
+
+Level 1 is the least strict level, and applies the fewest rules and returns the fewest results.
+
+As you increase the level, the stricter PHPStan is.
+
+## Levelling up to 9
+
+Here is the code to get the values of the `--extra-args` and `--working-dir` options:
+
+```language-php
+$extraArgs = $input->getOption('extra-args');
+$workingDir = $input->getOption('working-dir');
+```
+
+This passed PHPStan level 8, but these are the errors I get when running level 9:
+
+```language-plain
+------ -------------------------------------------------------------------------------------------------------
+ Line   versa
+------ -------------------------------------------------------------------------------------------------------
+ 61     Parameter $extraArgs of static method App\Process\Process::create() expects string|null, mixed given.
+ 62     Parameter $workingDir of static method App\Process\Process::create() expects string, mixed given.
+ 72     Parameter $extraArgs of static method App\Process\Process::create() expects string|null, mixed given.
+ 73     Parameter $workingDir of static method App\Process\Process::create() expects string, mixed given.
+ 84     Parameter $extraArgs of static method App\Process\Process::create() expects string|null, mixed given.
+ 85     Parameter $workingDir of static method App\Process\Process::create() expects string, mixed given.
+ 94     Parameter $extraArgs of static method App\Process\Process::create() expects string|null, mixed given.
+ 95     Parameter $workingDir of static method App\Process\Process::create() expects string, mixed given.
+ 104    Parameter $extraArgs of static method App\Process\Process::create() expects string|null, mixed given.
+ 105    Parameter $workingDir of static method App\Process\Process::create() expects string, mixed given.
+ 119    Parameter $extraArgs of static method App\Process\Process::create() expects string|null, mixed given.
+ 120    Parameter $workingDir of static method App\Process\Process::create() expects string, mixed given.
+------ -------------------------------------------------------------------------------------------------------
+
+[ERROR] Found 12 errors
+```
+
+The issue is that `$input->getOption()` from Symfony's `InputInterface` returns `mixed` - even though it always returns `null` or a string.
+
+If I did `--working-dir 2`, it would return the string `"2"`.
+
+An empty string throws an error, and an empty value (if there are no extra arguments) returns `null`.
+
+So, I know `$workingDir` will always be a string and `$extraArgs` will either a string or `null`.
+
+## Passing level 8
+
+To pass level 8, PHPStan needs to be sure the variables are what I think they are.
+
+Here's the code I can use to get it to pass:
+
+```language-php
+$extraArgs = $input->getOption('extra-args');
+$workingDir = $input->getOption('working-dir');
+assert(is_string($extraArgs) || is_null($extraArgs));
+assert(is_string($workingDir));
+```
+
+By using `assert()` and throwing an Exception if the condition fails, PHPStan is now happy with the code and my code passes level 9.
+
+## Here's the thing
+
+Although the extra code gets PHPStan to pass, it it worth it?
+
+Is this extra code adding value? Does it make the code more readable or is it likely to prevent a bug?
+
+In this case, I know the value will always be the type I expect.
+
+I can work around this using a baseline or annotations for PHPStan to ignore these lines, **or is level 8 good enough for this project**?
+
+Similar to 100% test coverage, is aiming for the highest PHPStan level an objective to be met, or is enough value being added added by the lower level?
+
+Which level is right for you and this codebase?
+
+[versa]: {{site.url}}