ForTestingOnly

{{#if:{{{parameter1}}}|{{{parameter2}}}|{{{parameter3}}}}}

{{#if: first parameter | second parameter | third parameter }}

"This function first tests whether the first parameter is not empty. If the first parameter is not empty the function displays the second argument. If the first parameter is empty or contains only whitespace characters (spaces, newlines, etc.) it displays the third argument."

-- from: MediaWiki Help:Extension:ParserFunctions##if