Panel 1: Connie feeds into Elly's "children are implacable adversaries plotting her ruin" fetish by reminding her that she sees being a parent as a power struggle. Parents get to make all the (arbitrary) rules (that change on a whim but still somehow manage to ensure that the child cannot win) and kids have to test them (because they are born with an evil tendency called 'free will' that is a horrible burden to imbecile bullies like Connie and Elly).
Panel 2: He also has to test her at every turning. He has to test Elly's strength (which is overbearingly strong when the matter fought over is meaningless but fades to nothingness when it actually matters if she sticks to her guns), her honesty (which is as illusory as her firmness), her convictions (which should be for child neglect) and her (self-serving) character.
Panel 3: He'll test her endurance (which fades to nothing when he smirks and shrugs when she proposes wearing shorts), her love (which is contingent on his not doing anything to make her angry) and her ability to forgive (which is known for the purity of its absence); he'll test everything (and find her wanting).
Panel 4: It's a tribute to something or other that one can hear the panic in Elly's voice when she asks "When will I know that I've passed?"
Summary: The answer is really simple, Ellybun: "When you stop thinking of your children as monsters trying to destroy you and when you stop hanging around self-destructive, pea-brained bullshit artists like Connie who tell you what you want to hear instead of what you need to hear."
(Of course, Connie's answer is "When the horrible child is so cowed by your hysterical shrieking that he voluntarily stops acting like a teenager.")