Use to compare a template with its sandbox. Pass the raw code in nowikis as the first unnamed parameter; the existing template as the second, and the sandbox as the third. The optional named parameter |id= is used as a heading (to describe the test being performed); if |id= is omitted, parameter 1 is used. The optional named parameter |layout= determines whether the live and sandbox outputs are displayed side by side or on top of each other. The default value is vertical (on top of each other). A value of horizontal will produce side by side output.
If the pair of test codes in parameters 2 and 3 both produce the same output, then the test case is displayed in a collapsed table with a green heading. If the test codes produce different output (this includes white space differences), then the test is displayed in an uncollapsed table with a yellow heading.
Note that some more complex templates may cause testcases to be highlighted even when their output is the same. The cause of this is under investigation...