Add vimeo/psalm

Author: devanych

.gitattributes

@@ -7,3 +7,4 @@
 /.scrutinizer.yml   export-ignore
 /phpcs.xml          export-ignore
 /phpunit.xml.dist   export-ignore
+/psalm.xml          export-ignore

composer.json

@@ -26,7 +26,8 @@
     },
     "require-dev": {
         "phpunit/phpunit": "^9.1",
-        "squizlabs/php_codesniffer": "^3.5"
+        "squizlabs/php_codesniffer": "^3.5",
+        "vimeo/psalm": "^3.12"
     },
     "autoload": {
         "psr-4": {
@@ -40,10 +41,12 @@
     },
     "scripts": {
         "test": "phpunit --colors=always",
+        "static": "psalm",
         "cs-check": "phpcs",
         "cs-fix": "phpcbf",
         "check": [
             "@cs-check",
+            "@static",
             "@test"
         ]
     }

psalm.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0"?>
+<psalm
+    totallyTyped="true"
+    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"
+>
+    <projectFiles>
+        <directory name="src" />
+        <ignoreFiles>
+            <directory name="vendor" />
+        </ignoreFiles>
+    </projectFiles>
+
+    <issueHandlers>
+        <DocblockTypeContradiction errorLevel="info" />
+        <LessSpecificImplementedReturnType errorLevel="info" />
+        <MixedArgumentTypeCoercion errorLevel="info" />
+        <MixedAssignment errorLevel="info" />
+        <MixedPropertyTypeCoercion errorLevel="info" />
+        <PropertyNotSetInConstructor errorLevel="info" />
+        <RedundantConditionGivenDocblockType errorLevel="info" />
+    </issueHandlers>
+</psalm>

src/RequestTrait.php

@@ -245,7 +245,7 @@ private function init(
     /**
      * Set and validate the HTTP method
      *
-     * @param mixed $method
+     * @param string $method
      * @throws InvalidArgumentException for invalid HTTP method.
      */
     private function setMethod(string $method): void