How to write tests that expect errors¶

Define a helper that catches an error and returns its code:

      #import $::error::ea
      #import $::error::en
      expect ← {'en 0' ea ⍵}

Then test that specific expressions produce specific errors:

      3 = expect '1÷0'
1

      6 = expect '10⌷⍳5'
1

      4 = expect '1 2+1 2 3'
1

The pattern works because ea catches the error and en 0 returns its code. The comparison then checks for the expected error type.