Test Case Reduction

A general guide to test case reduction

-The basic idea behind bug reduction is to take a page that demonstrates a problem and -remove as much content as possible while still reproducing the original problem. -

Why is this needed?

-A reduced test case can help identify the central problem on the -page by eliminating irrelevant information, i.e., portions of the HTML -page's structure that have nothing to do with the problem. -With a reduced test case, the development team will spend -less time identifying the problem and more time determining the -solution. Also, since a site can change its content or design, the -problem may no longer occur on the real-world site. -By constructing a test case you can capture the initial problem. -

The first steps

-Really the first step in reducing a page is to identify that main -problem of the page. For example: -

Does the page have text overlapping an image?
Is there a form button that fails to work?
Is there a portion of the page missing or misaligned?

-After you have made this determination, you need to create a local copy -of the page created from the page source window. After saving this -source, it's a good idea to put a <BASE> element in the -HEAD so that any images/external style sheet or scripts that use a -relative path will get loaded. After the BASE element has been added, -load the local copy into the browser and verify that problem is still -occurring. In this case, let's assume the problem is still present. -

Work from top to bottom

-In general, it's best to start from the top of the <DOCTYPE> and -work down through the HEAD to the BODY element. Take a look at the HTML -file in a text editor and view what types of elements are present in the -<head>. Typically, the HEAD will include the <title> -element, which is required, and elements such as <link>, -<style> and <script>. -

-The reduction process is to remove one element at a time, save, and reload the -test case. If you have removed the element and the page is still -displaying the problem, continue with the next element. If removing an -element in the HEAD causes the problem to not occur, you may have found -one piece in of the problem. Re-add this element back into the HEAD, -reload the page and confirm the problem is still occurring and move -on to the next element in the HEAD. -

A general guide to test case reduction

+ The basic idea behind bug reduction is to take a page that demonstrates a problem and + remove as much content as possible while still reproducing the original problem. +

+ +

Why is this needed?

+ A reduced test case can help identify the central problem on the + page by eliminating irrelevant information, i.e., portions of the HTML + page's structure that have nothing to do with the problem. + With a reduced test case, the development team will spend + less time identifying the problem and more time determining the + solution. Also, since a site can change its content or design, the + problem may no longer occur on the real-world site. + By constructing a test case you can capture the initial problem. +

+ +

The first steps

+ Really the first step in reducing a page is to identify that main + problem of the page. For example: +

Does the page have text overlapping an image?
Is there a form button that fails to work?
Is there a portion of the page missing or misaligned?

+ After you have made this determination, you need to create a local copy + of the page created from the page source window. After saving this + source, it's a good idea to put a <BASE> element in the + HEAD so that any images/external style sheet or scripts that use a + relative path will get loaded. After the BASE element has been added, + load the local copy into the browser and verify that problem is still + occurring. In this case, let's assume the problem is still present. +

Finished the `HEAD`? Continue with the `BODY`!

-Once the HEAD element has been reduced, you need to start reducing -the number of required elements in the BODY. This will tend to be the -most time consuming since hundreds (thousands) of elements will be -present. The general practice is start removing elements by both their -<start> and </end> elements. This is especially true for -tables, which are frequently nested. You can speed up this process by -selecting groups of elements and removing them but ideally you need to -save and reload the test case each time to verify the problem is -happening. -

-Another way to help you identify unnecessary elements is to temporary -uncheck 'Enable Javascript' in the Preferences. If you turn this option -off and loading your test case still reproduces the problem, then any -script elements that are present can be removed since they are not a -factor in this issue. Let's say that you have reduced the page down to -a nested table with an ordered list with an <link> element that need -to be present. It's good practice to identify that CSS rule that is -being in the external file and add it directly to the test case. Create -a <style> </style> in the head and copy/paste the contents -of the .css file into this style element. Remove the <link> and -save the changes. Load the test case and verify the problem is still -occurring. Now manually delete or comment out each CSS rule until you -have just the required set of rules to reproduce. -

Work from top to bottom

+ In general, it's best to start from the top of the <DOCTYPE> and + work down through the HEAD to the BODY element. Take a look at the HTML + file in a text editor and view what types of elements are present in the + <head>. Typically, the HEAD will include the <title> + element, which is required, and elements such as <link>, + <style> and <script>. +

+ The reduction process is to remove one element at a time, save, and reload the + test case. If you have removed the element and the page is still + displaying the problem, continue with the next element. If removing an + element in the HEAD causes the problem to not occur, you may have found + one piece in of the problem. Re-add this element back into the HEAD, + reload the page and confirm the problem is still occurring and move + on to the next element in the HEAD. +

+ +

Finished the `HEAD`? Continue with the `BODY`!

+ Once the HEAD element has been reduced, you need to start reducing + the number of required elements in the BODY. This will tend to be the + most time consuming since hundreds (thousands) of elements will be + present. The general practice is start removing elements by both their + <start> and </end> elements. This is especially true for + tables, which are frequently nested. You can speed up this process by + selecting groups of elements and removing them but ideally you need to + save and reload the test case each time to verify the problem is + happening. +

+ +

Another method

+ Another way to help you identify unnecessary elements is to temporary + uncheck 'Enable Javascript' in the Preferences. If you turn this option + off and loading your test case still reproduces the problem, then any + script elements that are present can be removed since they are not a + factor in this issue. Let's say that you have reduced the page down to + a nested table with an ordered list with an <link> element that need + to be present. It's good practice to identify that CSS rule that is + being in the external file and add it directly to the test case. Create + a <style> </style> in the head and copy/paste the contents + of the .css file into this style element. Remove the <link> and + save the changes. Load the test case and verify the problem is still + occurring. Now manually delete or comment out each CSS rule until you + have just the required set of rules to reproduce. +

+ +

Adding to the bug

+ When you've finished your reduction, you should add it to the bug. It's quite likely + that in the process of reducing, you have found the root cause of the problem, so + you are able to set the right component. If you do not have the rights to change + the component, read about how to get them in this document + about Bugzilla. +

Test Case Reduction

A general guide to test case reduction

Why is this needed?

The first steps

Work from top to bottom

A general guide to test case reduction

Why is this needed?

The first steps

Finished the HEAD? Continue with the BODY!

Work from top to bottom

Finished the HEAD? Continue with the BODY!

Another method

Adding to the bug

Finished the `HEAD`? Continue with the `BODY`!

Finished the `HEAD`? Continue with the `BODY`!