Check for boolean false and add tests

Signed-off-by: Morris Jobke <hey@morrisjobke.de>

lib/private/Config.php

@@ -86,7 +86,7 @@ class Config {
 	 */
 	public function getValue($key, $default = null) {
 		$envValue = getenv(self::ENV_PREFIX . $key);
-		if ($envValue) {
+		if ($envValue !== false) {
 			return $envValue;
 		}
 

tests/lib/ConfigTest.php

@@ -52,6 +52,21 @@ class ConfigTest extends TestCase {
 		$this->assertEquals('bar', $this->config->getValue('foo'));
 		putenv('NC_foo=baz');
 		$this->assertEquals('baz', $this->config->getValue('foo'));
+		putenv('NC_foo'); // unset the env variable
+	}
+
+	public function testGetValueReturnsEnvironmentValueIfSetToZero() {
+		$this->assertEquals('bar', $this->config->getValue('foo'));
+		putenv('NC_foo=0');
+		$this->assertEquals('0', $this->config->getValue('foo'));
+		putenv('NC_foo'); // unset the env variable
+	}
+
+	public function testGetValueReturnsEnvironmentValueIfSetToFalse() {
+		$this->assertEquals('bar', $this->config->getValue('foo'));
+		putenv('NC_foo=false');
+		$this->assertEquals('false', $this->config->getValue('foo'));
+		putenv('NC_foo'); // unset the env variable
 	}
 
 	public function testSetValue() {