$differenceEngine = new DifferenceEngine();
$diff = $differenceEngine->generateContentDiffBody( $oldContent, $newContent );
$this->assertSame( $expectedDiff, $this->getPlainDiff( $diff ) );
$differenceEngine = new DifferenceEngine();
$diff = $differenceEngine->generateContentDiffBody( $oldContent, $newContent );
$this->assertSame( $expectedDiff, $this->getPlainDiff( $diff ) );