Add static analysis with phpstan

.gitattributes

@@ -4,5 +4,7 @@
 /.github/ export-ignore
 /CONTRIBUTING.md export-ignore
 /fixtures/ export-ignore
+/phpstan-fixtures/ export-ignore
+/phpstan.dist.neon export-ignore
 /phpunit.xml.dist export-ignore
 /tests/ export-ignore

.github/workflows/ci.yml

@@ -64,3 +64,18 @@ jobs:
 
       - name: Execute Unit Tests
         run: vendor/bin/phpunit
+
+  phpstan:
+    runs-on: ubuntu-latest
+    name: Static analysis
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: "8.2"
+          ini-file: development
+          coverage: none
+      - name: Install dependencies
+        run: composer update --ansi --no-interaction --no-progress
+      - run: ./vendor/bin/phpstan

composer.json

@@ -24,12 +24,16 @@
     "autoload-dev": {
         "psr-4": {
             "Prophecy\\PhpUnit\\Tests\\Fixtures\\": "fixtures",
+            "Prophecy\\PhpUnit\\Tests\\PhpstanFixtures\\": "phpstan-fixtures",
             "Prophecy\\PhpUnit\\Tests\\": "tests"
         }
     },
     "extra": {
         "branch-alias": {
             "dev-master": "2.x-dev"
         }
+    },
+    "require-dev": {
+        "phpstan/phpstan": "^1.10"
     }
 }

phpstan-fixtures/ExampleUsage.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace Prophecy\PhpUnit\Tests\PhpstanFixtures;
+
+use PHPUnit\Framework\TestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
+use Prophecy\Prophecy\ObjectProphecy;
+
+class ExampleUsage extends TestCase
+{
+    use ProphecyTrait;
+
+    public function testExplicitClass(): void
+    {
+        $prophecy = $this->prophesize(\DateTimeImmutable::class);
+
+        $this->configureDouble($prophecy);
+
+        $double = $prophecy->reveal();
+
+        $this->checkValue($double->format('Y-m-d'));
+    }
+
+    /**
+     * @param ObjectProphecy<\DateTimeImmutable> $double
+     */
+    private function configureDouble(ObjectProphecy $double): void
+    {
+    }
+
+    private function checkValue(string $value): void
+    {
+        self::assertNotEmpty($value);
+    }
+}

phpstan.dist.neon

@@ -0,0 +1,11 @@
+parameters:
+    level: 9
+    treatPhpDocTypesAsCertain: false
+    paths:
+        - ./src/
+        - ./phpstan-fixtures/
+    ignoreErrors:
+        # recordDoubledType exist only in PHPUnit < 10 but the code is checking that before using it.
+        -
+            message: '#^Call to an undefined method Prophecy\\PhpUnit\\Tests\\PhpstanFixtures\\[^:]++\:\:recordDoubledType\(\)\.$#'
+            path: src/ProphecyTrait.php

src/ProphecyTrait.php

@@ -98,6 +98,7 @@ protected function tearDownProphecy(): void
     private function countProphecyAssertions(): void
     {
         \assert($this instanceof TestCase);
+        \assert($this->prophet !== null);
         $this->prophecyAssertionsCounted = true;
 
         foreach ($this->prophet->getProphecies() as $objectProphecy) {