testing shows the action that you are doing, therefore, it also shows that it is in progress, and it is repeated by the words "in progress" best use "the tests (noun) are in progress" because you are doing many, not one presumably
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AvangiI'm curious about the title of the thread. It's hard to imagine "testing" as an adjective
dimsumexpress
If I am running a 24 test in a lab that I don't want anyone to interfere with, I would post a sign on the door "Do not enter. Test is in progress, ", No "the".
Avangi
Perhaps someday we'll have a special forum for signs.
"The" is called a definite article. When you wish to indicate that (a) particular (definite) test/tests/testing/series of tests is/are being conducted, "The" is appropriate.
In some cases the article should be omitted; in some cases it may be omitted; in some cases it may not be omitted.