Increase assert interface coverage

[sukrosono]

List of targets:

• changes with getter function without message ok

• changesBy with getter function without message
  fail with expecting getter function to have .value

• doesNotChange with getter function without message ok

• changesButNotBy with getter function without message
  fail with expecting getter function to have .value

• increases and decreases with getter function without message notOk

  decreasesBy fail with expecting getter function to have .value

  decreasesButNotBy fail with expecting getter function to have .value

  so do with the increasesBy and increasesButNotBy

I seems that i need some help with explaining or pointing why it expecting getter function to have specific property.

[keithamus]

Hey @brutalcrozt thanks for this issue.

We're going to work a bunch on chai soon. We'll be looking at increasing test coverage of all of our assertions. I'll close this for now because there's nothing specifically actionable from this issue!