how did lysander and hermia came to be in the forest and say how their 'true love' is put to the test there?

Lysander and Hermia flee to the forest. Once there, they will elope by travelling to Lysander's aunt's house (which is outside of Athenian jurisdiction) and get married. Just before they are to elope. Puck, the magic sprite, confuses the couple Oberon has instructed him to pour love juice on. Instead he pours it on Lysander who immediately falls in love with Helena (who is in love with Demetrius). So it's all a big mess and the regional two lovebirds are tested until the whole mess gets sorted out, as it always does, in a Shakespearean comedy.