From 1f87afa8e680918fcfaae990b52fd862800d67f6 Mon Sep 17 00:00:00 2001
From: Thiemo Kreuz <thiemo.kreuz@wikimedia.de>
Date: Fri, 13 Apr 2018 15:50:34 +0200
Subject: [PATCH] Fix MathFormatter failing on new SnakFormatter format MIME
 types

A formatter like this is not supposed to check if the format is known
or not. The code calling these formatters can introduce new (sub) formats
any time. What a formatter like this should do then are two things:
* If it's some HTML format, always return HTML.
* If you really can't identify the format, do a sensible fallback.

This currently blocks introducing a new format in Wikibase.

Bug: T46727
Change-Id: I585069e8f2ba33ec657ca4d514c6d502fe0f5ba3
---
 MathFormatter.php           | 16 +++-------------
 tests/MathFormatterTest.php | 10 +++++-----
 2 files changed, 8 insertions(+), 18 deletions(-)

diff --git a/MathFormatter.php b/MathFormatter.php
index c21a1fc..966faa0 100644
--- a/MathFormatter.php
+++ b/MathFormatter.php
@@ -25,20 +25,9 @@ class MathFormatter implements ValueFormatter {
 	 * Loads format to distinguish the type of formatting
 	 *
 	 * @param string $format One of the SnakFormatter::FORMAT_... constants.
-	 *
-	 * @throws InvalidArgumentException
 	 */
 	public function __construct( $format ) {
-		switch ( $format ) {
-			case SnakFormatter::FORMAT_PLAIN:
-			case SnakFormatter::FORMAT_WIKI:
-			case SnakFormatter::FORMAT_HTML:
-			case SnakFormatter::FORMAT_HTML_DIFF:
-				$this->format = $format;
-				break;
-			default:
-				throw new InvalidArgumentException( 'Unsupported output format: ' . $format );
-		}
+		$this->format = $format;
 	}
 
 	/**
@@ -59,6 +48,8 @@ class MathFormatter implements ValueFormatter {
 				return $tex;
 			case SnakFormatter::FORMAT_WIKI:
 				return "<math>$tex</math>";
+
+			// Intentionally fall back to MathML output in all other, possibly unknown cases.
 			default:
 				$renderer = new MathMathML( $tex );
 
@@ -72,7 +63,6 @@ class MathFormatter implements ValueFormatter {
 					$html = $this->formatDetails( $html, $tex );
 				}
 
-				// TeX string is not valid or rendering failed
 				return $html;
 		}
 	}
diff --git a/tests/MathFormatterTest.php b/tests/MathFormatterTest.php
index fec365d..a435a70 100644
--- a/tests/MathFormatterTest.php
+++ b/tests/MathFormatterTest.php
@@ -58,11 +58,11 @@ class MathFormatterTest extends MediaWikiTestCase {
 		$formatter->format( null );
 	}
 
-	/**
-	 * @expectedException InvalidArgumentException
-	 */
-	public function testUnknownFormat() {
-		new MathFormatter( 'unknown/unknown' );
+	public function testUnknownFormatFallsBackToMathMl() {
+		$formatter = new MathFormatter( 'unknown/unknown' );
+		$value = new StringValue( self::SOME_TEX );
+		$resultFormat = $formatter->format( $value );
+		$this->assertContains( '</math>', $resultFormat );
 	}
 
 	public function testFormatPlain() {