Pregnancy test

Hi,

Total random one, but do all pregnancy tests show up as a line when held in the sun? And then when brought back to non sun nothing there?

I took a huge chance as I had a really random huge drop on my chart at 10dpo which is early for me, then the next day I got creamy cm with a little bulb of very small tissue is what it looked like, then the day after i started to bleed, again all early i usually don't start to bleed till 14dpo which would be today, well today my bleeding has stopped, it wasn't very heavy these past 2 days just light but red, I know that means period when it's red however just with everything being a bit odd i took a test, it's a sunny day so when I told it to the sun there is a line, take it away and hold not in the sun it's gone, is this normal for a test?