Narrow types

Author: sebastianbergmann

.psalm/baseline.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<files psalm-version="5.18.0@b113f3ed0259fd6e212d87c3df80eec95a6abf19">
+<files psalm-version="5.19.1@b9583493b08eb36259c0f6b746a787c4c9b3ac45">
   <file src="src/Framework/Assert.php">
     <ArgumentTypeCoercion>
       <code><![CDATA[$actualElement->childNodes->item($i)]]></code>
@@ -1210,6 +1210,14 @@
       <code><![CDATA[$this->cache !== null]]></code>
     </RedundantConditionGivenDocblockType>
   </file>
+  <file src="src/Runner/Version.php">
+    <LessSpecificReturnStatement>
+      <code><![CDATA[implode('.', array_slice(explode('.', $version), 0, 2))]]></code>
+    </LessSpecificReturnStatement>
+    <MoreSpecificReturnType>
+      <code>non-empty-string</code>
+    </MoreSpecificReturnType>
+  </file>
   <file src="src/TextUI/CliArguments/Builder.php">
     <ArgumentTypeCoercion>
       <code>$parameters</code>

src/Runner/Version.php

@@ -10,6 +10,7 @@
 namespace PHPUnit\Runner;
 
 use function array_slice;
+use function assert;
 use function dirname;
 use function explode;
 use function implode;
@@ -33,6 +34,8 @@ final class Version
 
     /**
      * Returns the current version of PHPUnit.
+     *
+     * @psalm-return non-empty-string
      */
     public static function id(): string
     {
@@ -42,11 +45,16 @@ public static function id(): string
 
         if (self::$version === '') {
             self::$version = (new VersionId('9.6.15', dirname(__DIR__, 2)))->getVersion();
+
+            assert(!empty(self::$version));
         }
 
         return self::$version;
     }
 
+    /**
+     * @psalm-return non-empty-string
+     */
     public static function series(): string
     {
         if (strpos(self::id(), '-')) {
@@ -58,6 +66,9 @@ public static function series(): string
         return implode('.', array_slice(explode('.', $version), 0, 2));
     }
 
+    /**
+     * @psalm-return non-empty-string
+     */
     public static function getVersionString(): string
     {
         return 'PHPUnit ' . self::id() . ' by Sebastian Bergmann and contributors.';