Too verbose tests

[apaatsio]

Some tests could be refactored to make them simpler.

For example:

trees_company/test/credit_card_test.dart

Lines 17 to 24 in a238aad

	bool stateIsNotNull = false;
	PaymentDetails page = PaymentDetails();
	var state = page.createState();
	stateIsNotNull = state != null;
	expect(stateIsNotNull, true);

Could be written just

PaymentDetails page = PaymentDetails();
expect(page.createState(), isNotNull);

There were other tests also that used a similar pattern.