Fix elements with content of "0" not being rendered (fixes #376)

CHANGELOG.md

@@ -4,6 +4,10 @@ Updates should follow the [Keep a CHANGELOG](https://keepachangelog.com/) princi
 
 ## [Unreleased][unreleased]
 
+### Fixed
+
+ - Fixed bug where elements with content of `"0"` wouldn't be rendered (#376)
+
 ## [0.19.2] - 2019-05-19
 
 ### Fixed

src/HtmlElement.php

@@ -38,7 +38,7 @@ public function __construct(string $tagName, array $attributes = [], $contents =
         $this->attributes = $attributes;
         $this->selfClosing = $selfClosing;
 
-        $this->setContents($contents ?: '');
+        $this->setContents($contents ?? '');
     }
 
     /**
@@ -111,7 +111,7 @@ public function getContents(bool $asString = true)
      */
     public function setContents($contents): self
     {
-        $this->contents = $contents ?: '';
+        $this->contents = $contents ?? '';
 
         return $this;
     }

src/Inline/Parser/CloseBracketParser.php

@@ -162,7 +162,7 @@ protected function tryParseInlineLinkAndTitle(Cursor $cursor)
         $title = '';
         // make sure there's a space before the title:
         if (\preg_match(RegexHelper::REGEX_WHITESPACE_CHAR, $cursor->peek(-1))) {
-            $title = LinkParserHelper::parseLinkTitle($cursor) ?: '';
+            $title = LinkParserHelper::parseLinkTitle($cursor) ?? '';
         }
 
         $cursor->advanceToNextNonSpaceOrNewline();

tests/unit/HtmlElementTest.php

@@ -114,4 +114,17 @@ public function testNullContentSetter()
         $img->setContents(null);
         $this->assertTrue($img->getContents(false) === '');
     }
+
+    /**
+     * See https://github.com/thephpleague/commonmark/issues/376
+     */
+    public function testRegressionWith0NotBeingRendered()
+    {
+        $element = new HtmlElement('em');
+        $element->setContents('0');
+        $this->assertSame('0', $element->getContents());
+
+        $element = new HtmlElement('em', [], '0');
+        $this->assertSame('0', $element->getContents());
+    }
 }