README.md

@@ -227,7 +227,7 @@ One or more environment variables failed assertions: FOO is not an integer
 
 ### Boolean Variables
 
-You may need to ensure a variable is in the form of a boolean, accepting "On", "1", "Yes", "Off", "0" and "No". You may do the following:
+You may need to ensure a variable is in the form of a boolean, accepting "true", "false", "On", "1", "Yes", "Off", "0" and "No". You may do the following:
 
 ```php
 $dotenv->required('FOO')->isBoolean();

composer.json

@@ -21,13 +21,17 @@
         "symfony/polyfill-ctype": "^1.9"
     },
     "require-dev": {
+        "ext-filter": "*",
         "phpunit/phpunit": "^4.8.35 || ^5.0 || ^6.0 || ^7.0"
     },
     "autoload": {
         "psr-4": {
             "Dotenv\\": "src/"
         }
     },
+    "suggest": {
+        "ext-filter": "Required to use the boolean validator."
+    },
     "extra": {
         "branch-alias": {
             "dev-master": "3.6-dev"

src/Lines.php

@@ -22,7 +22,7 @@ public static function process(array $lines)
         foreach ($lines as $line) {
             list($multiline, $line, $multilineBuffer) = self::multilineProcess($multiline, $line, $multilineBuffer);
 
-            if (!$multiline && !self::isComment($line) && self::isSetter($line)) {
+            if (!$multiline && !self::isCommentOrWhitespace($line)) {
                 $output[] = $line;
             }
         }
@@ -115,28 +115,20 @@ private static function getCharPairs($line)
     }
 
     /**
-     * Determine if the line in the file is a comment, e.g. begins with a #.
+     * Determine if the line in the file is a comment or whitespace.
      *
      * @param string $line
      *
      * @return bool
      */
-    private static function isComment($line)
+    private static function isCommentOrWhitespace($line)
     {
+        if (trim($line) === '') {
+            return true;
+        }
+
         $line = ltrim($line);
 
         return isset($line[0]) && $line[0] === '#';
     }
-
-    /**
-     * Determine if the given line looks like it's setting a variable.
-     *
-     * @param string $line
-     *
-     * @return bool
-     */
-    private static function isSetter($line)
-    {
-        return strpos($line, '=') !== false;
-    }
 }

tests/Dotenv/DotenvTest.php

@@ -236,6 +236,12 @@ public function testMutlilineLoading()
         $this->assertSame('https://vision.googleapis.com/v1/images:annotate?key=', getenv('TEST_EQS'));
     }
 
+    public function testEmptyLoading()
+    {
+        $dotenv = Dotenv::create($this->fixturesFolder, 'empty.env');
+        $this->assertSame(['EMPTY_VAR' => null], $dotenv->load());
+    }
+
     public function testGetEnvironmentVariablesList()
     {
         $dotenv = Dotenv::create($this->fixturesFolder);

tests/fixtures/env/empty.env

@@ -0,0 +1 @@
+EMPTY_VAR