You can record
multiple user scenarios in a test and then run each scenario in a
random order. To do this, you put each scenario under a random selector
and then select the proportion of time that the scenario should be
run.
About this task
For example, you can record a test that includes logging
on to a system, browsing through items in the system, buying various
items, and then totaling the order. In this case, you could run the
logging in and the totaling scenarios once, but put the browsing and
buying scenarios under a random selector.
Procedure
- In the Test Navigator, browse to the test and double-click
it. The test opens.
- Click the test element that will be controlled by the random
selector, and then click . Use
Shift+Click to select multiple elements.
- You are asked whether you want to move the selected elements
into a new random selector. Click Yes. Click No to insert an empty random selector
into the test.
Note: To set whether or not elements are moved automatically,
or whether you are prompted, click , and click the General tab.
- Set the weight of the random selector. The weight determines
the statistical probability that a specific element will be selected.
- If you have added a number of test elements, the Create
weighted blocks window is displayed. You can select adjacent
elements and group them. Each element—whether in a group or by itself—must
be weighted.
- If you have added only one test element, the weighted
block is displayed in the Test Element Details area with a
default of 1.
Example
When a selector contains many different
weights, you can mathematically determine the likelihood that a block
will be executed. To do this, add the weights together and divide
the weight for each block by that total.
For example, assume a selector
contains six blocks set to the following weight:
- two blocks set to a weight of 1
- one block set to a weight of 2
- two blocks set to a weight of 5
- one block set to a weight of 9
The total of the weights is: 1 + 1 + 2 + 5 + 5 + 9 = 23. Therefore,
the statistical likelihood of selection is:
Weight of block |
Likelihood of block being selected |
1 (two blocks) |
1/23. = 0.0435, or about 4.35% (for each block) |
2 |
2/23 = 0.0870, or about 8.70% |
5 (two blocks) |
5/23 = 0.2174, or about 21.74% (for each block) |
9 |
9/23 = 0.3913, or about 39.13% |
Note that a higher weight increases the likelihood,
but does not guarantee, that a block will be executed. Some variation
might occur. For example, if you run a test 23 times, you cannot predict
that the first and second blocks will execute exactly once, the third
block exactly twice, the fourth and fifth blocks exactly five times,
and the sixth block exactly nine times. However, the more times that
the blocks are executed, the more accurate this prediction is.