Throw exception if level < 0

Author: dantleech

lib/Util/TextFormat.php

@@ -2,6 +2,8 @@
 
 namespace Phpactor\CodeBuilder\Util;
 
+use RuntimeException;
+
 class TextFormat
 {
     /**
@@ -22,6 +24,11 @@ public function __construct(string $indentation = '    ', string $newLineChar =
 
     public function indent(string $string, int $level = 0): string
     {
+        if ($level < 0) {
+            throw new RuntimeException(sprintf(
+                'Level must be greater than or equal to 0, got "%s"', $level
+            ));
+        }
         $lines = TextUtil::lines($string);
         $lines = array_map(function ($line) use ($level) {
             return str_repeat($this->indentation, $level) . $line;

tests/Unit/Util/TextFormatTest.php

@@ -4,6 +4,7 @@
 
 use PHPUnit\Framework\TestCase;
 use Phpactor\CodeBuilder\Util\TextFormat;
+use RuntimeException;
 
 class TextFormatTest extends TestCase
 {
@@ -139,6 +140,12 @@ public function provideIndent()
         ];
     }
 
+    public function testIndentExceptionIfLevelLessThan0()
+    {
+        $this->expectException(RuntimeException::class);
+        (new TextFormat())->indent('foobar', -1);
+    }
+
     public function testReplacesIndentation()
     {
         $this->assertEquals(<<<'EOT'