TechInfoDepot:Template sandbox and test cases

Templates are a very powerful feature of MediaWiki, but mistakes can be easily made, even by experienced users. Complex templates should therefore be accompanied by sandboxes and test cases to prevent bugs.

For what kind of templates
It is recommended to apply the test case pattern to templates using ParserFunctions that can generate very different looking output, such as the ones that take many parameters, or the ones that have many branches of the #switch operator.

For navigational boxes, of which the outputs are almost identical on each transcluding page, the benefit may not outweigh the time and effort.

Any template that is transcluded in thousands of pages should of course be tested before an edit is made.

Prerequisite
The template must be properly documented following TechInfoDepot:Template documentation.

Furthermore, the template should not have too many interleaving   and   blocks. Ideally there is only one   block, placed at the bottom of the template, and containing the documentation template.

How to create /sandbox and /testcases subpages
1: Suppose your template is named Template:X. Create a subpage with the name Template:X/sandbox and another with Template:X/testcases. When these subpages are present, the green /doc box produced by documentation automatically provide links to them. Note that "/sandbox" and "/testcases" are spelled in all lower-case.

2: Copy only the code (everything that is not surrounded by  ) from your Template:X</tt> to Template:X/sandbox</tt>. And add the following at the end of the last line, in the same line:



In other words, the result should be:



Note! The template code must start directly before and touch the  tag. Any blank space or newlines between the template code and the  tag can cause the template to render unwanted spaces or newlines when used.

3: Copy a few transcluding examples from articles ( </tt>) to your Template:X/testcases</tt>. In the test case subpage, duplicate each example, and for one copy of each example, replace X</tt> with X/sandbox</tt>. This is done so that you may compare the old and new outputs side by side in the future. Lastly, add the following line at the beginning of the test case page. It does not matter how many blank lines you put around it:



4: Thus Template:X/testcases</tt> will look like this:

4b: To make differences easier to identify, you can use Template:Testcase to lay out your test cases. Then, test cases which are changed in the sandbox are highlighted so you can double check that the change was intentional.

How to use them subsequently

 * Sync sandbox from the real template (i.e. step 2 above)
 * Have fun editing the sandbox
 * Verify the test cases
 * If everything looks good, copy the code from the sandbox to the real template

If you chose not to compare the new and old outputs side by side described at the last bullet point of the previous section, it is recommended to use a tabbed browser and open the test case subpage before changing the sandbox, and another after changing the sandbox. This can ensure that the differences are compared accurately.

Example

 * Infobox country
 * Infobox settlement

Test with other users - test-mode
If you are satisfied with the changes that you made in the sandbox version, and with what the test cases show - you might consider trying test-mode. This will enable several users to browse pages on TechInfoDepot with the test version of your template, and yet not affect anyone else displaying those pages.