124 Software teSting interview QueStionS
Unit testing DRE calculation is similar to system testing DRE. As you
can see from the following figure it’s nothing but the number of defects found
during unit testing divided by the number of defects found during unit testing
plus the number of defects found during system testing.
Figure 121 Unit test DRE calculation
One of the important factors to be noted while calculating unit testing
DRE is that we need to exclude those defects which cannot be produced
due to the limitations of unit testing. For instance, passing of data between
components to each other. In unit testing, because we test it as a single unit,
we can never reproduce defects which involve interaction. So such kinds of
defects should be removed to get accurate test results.
(i) hoW do you measure test effectiveness?
Test effectiveness is the measure of the bug-finding ability of our tests. In
short, it measures how good the tests were. So effectiveness is the ratio of
the measure of bugs found during testing to the total bugs found. Total bugs
are the sum of new defects found by the user plus the bugs found in the test.
The following figure explains the calculations in a pictorial format.

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