Add Psalm

Author: BenMorel

.github/workflows/ci.yml

@@ -5,6 +5,7 @@ on:
   pull_request:
 
 env:
+  PSALM_PHP_VERSION: "8.3"
   COVERAGE_PHP_VERSION: "8.3"
 
 jobs:
@@ -56,3 +57,22 @@ jobs:
         env:
           COVERALLS_REPO_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         if: ${{ matrix.php-version == env.COVERAGE_PHP_VERSION }}
+
+  psalm:
+    name: Psalm
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ env.PSALM_PHP_VERSION }}
+
+      - name: Install composer dependencies
+        uses: "ramsey/composer-install@v1"
+
+      - name: Run Psalm
+        run: vendor/bin/psalm --no-progress

composer.json

@@ -12,7 +12,8 @@
   },
   "require-dev": {
     "phpunit/phpunit": "^9.0",
-    "php-coveralls/php-coveralls": "^2.0"
+    "php-coveralls/php-coveralls": "^2.0",
+    "vimeo/psalm": "5.17.0"
   },
   "autoload": {
     "psr-4": {

psalm.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<psalm
+    errorLevel="1"
+    resolveFromConfigFile="true"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="https://getpsalm.org/schema/config"
+    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
+    findUnusedBaselineEntry="true"
+    findUnusedPsalmSuppress="true"
+    findUnusedCode="false"
+>
+    <projectFiles>
+        <directory name="src" />
+        <ignoreFiles>
+            <directory name="vendor" />
+        </ignoreFiles>
+    </projectFiles>
+</psalm>

src/Formatter/GBFormatter.php

@@ -47,6 +47,8 @@ class GBFormatter implements CountryPostcodeFormatter
     /**
      * The regular expression patterns, or null if not built yet.
      *
+     * @psalm-var non-empty-string[]|null
+     *
      * @var string[]|null
      */
     private $patterns = null;
@@ -86,6 +88,8 @@ public function format(string $postcode) : ?string
      * - The area code (ex: WC) for additional checks
      * - The inward code (e.g. 9RZ) for formatting
      *
+     * @psalm-return non-empty-string[]
+     *
      * @return string[]
      */
     private function getPatterns() : array

src/PostcodeFormatter.php

@@ -86,6 +86,7 @@ private function doGetFormatter(string $country): ?CountryPostcodeFormatter
             return null;
         }
 
+        /** @var class-string<CountryPostcodeFormatter> $class */
         $class = __NAMESPACE__ . '\\Formatter\\' . $country . 'Formatter';
 
         return class_exists($class) ? new $class() : null;