[DependencyInjection] Allow casting env var processors to cast null

Author: fancyweb

EnvVarProcessor.php

@@ -181,10 +181,12 @@ public function getEnv(string $prefix, string $name, \Closure $getEnv)
                 throw new RuntimeException(sprintf('Unsupported env var prefix "%s".', $prefix));
             }
 
-            return null;
+            if (!\in_array($prefix, ['string', 'bool', 'not', 'int', 'float'], true)) {
+                return null;
+            }
         }
 
-        if (!\is_scalar($env)) {
+        if (null !== $env && !\is_scalar($env)) {
             throw new RuntimeException(sprintf('Non-scalar env var "%s" cannot be cast to "%s".', $name, $prefix));
         }
 
@@ -199,15 +201,15 @@ public function getEnv(string $prefix, string $name, \Closure $getEnv)
         }
 
         if ('int' === $prefix) {
-            if (false === $env = filter_var($env, \FILTER_VALIDATE_INT) ?: filter_var($env, \FILTER_VALIDATE_FLOAT)) {
+            if (null !== $env && false === $env = filter_var($env, \FILTER_VALIDATE_INT) ?: filter_var($env, \FILTER_VALIDATE_FLOAT)) {
                 throw new RuntimeException(sprintf('Non-numeric env var "%s" cannot be cast to int.', $name));
             }
 
             return (int) $env;
         }
 
         if ('float' === $prefix) {
-            if (false === $env = filter_var($env, \FILTER_VALIDATE_FLOAT)) {
+            if (null !== $env && false === $env = filter_var($env, \FILTER_VALIDATE_FLOAT)) {
                 throw new RuntimeException(sprintf('Non-numeric env var "%s" cannot be cast to float.', $name));
             }
 

Tests/ContainerBuilderTest.php

@@ -839,8 +839,8 @@ public function testEnvAreNullable()
         $container->register('foo', 'stdClass')
             ->setPublic(true)
             ->setProperties([
-            'fake' => '%env(int:FAKE)%',
-        ]);
+                'fake' => '%env(resolve:FAKE)%',
+            ]);
 
         $container->compile(true);
 

Tests/EnvVarProcessorTest.php

@@ -760,4 +760,22 @@ public static function provideGetEnvUrlPath()
             ['blog//', 'https://symfony.com/blog//'],
         ];
     }
+
+    /**
+     * @testWith    ["", "string"]
+     *              [false, "bool"]
+     *              [true, "not"]
+     *              [0, "int"]
+     *              [0.0, "float"]
+     */
+    public function testGetEnvCastsNull($expected, string $prefix)
+    {
+        $processor = new EnvVarProcessor(new Container());
+
+        $this->assertSame($expected, $processor->getEnv($prefix, 'default::FOO', static function () use ($processor) {
+            return $processor->getEnv('default', ':FOO', static function () {
+                return null;
+            });
+        }));
+    }
 }