Ever since elementary school, you've been testing properties like acidity and alkalinity with litmus paper, haven't you.

Literal

Elementary-school [possessive-の] time [from-から], acidity/alkalinity [quotative-という] properties [object-を] litmus-paper [with-で] test-and-such have-been-doing [agreement-ね].

~てきています chains ~てくる (continuous up to now) with ~ています (ongoing state) to emphasize that this testing has been happening all along since childhood. ~たりする marks the action as one example among several. ~ね seeks agreement from the reader.