Why do you think that you have to “permanently forsake” one Tool, in order to take a gig that involves using a different Tool?
Also, frankly, don’t attach the meaning or actual importance to those “tests,” that the companies who make and sell them might encourage you to do. That makes about as much sense (to me) as giving a General Contractor a test on, say, Wrenches. (Measuring, o’course, their ability to drive a nail with one.)
The skills of a good programmer come only with Experience, and they are language-independent. (If you don’t believe me, search YouTube for “toy piano,” and listen to/watch the first three entries or so.) If you know what to do, you can do it with absolutely nothing ... for example, with PHP. ;-) ;-) ;-)
In the preliminary discussions leading up to most of the engagements I have won, there is usually an uncomfortable pause when the client says ... “well, we have some Perl code and some Python (DJango ...), and some PHP ... a little Java on the back-end.” And I simply smile and say that this is to be expected, and that I/we have recently done production work in all of them and can provide code samples. That is often what seals the deal ... yet I do consider it to be “perfectly normal,” i-f you have experience. The “one-trick ponies” are the ones who, at their present state in their careers, have working-knowledge only of one; often, PHP. They know the front-end but are lost in the back. (Not maligning any of them, mind you, nor the PHP language save in-jest. It does take time.)