function assert.error_message set -l number_of_arguments (count $argv) switch $argv[1] case ! switch $number_of_arguments case 3 set operator (assert.expand_operator $argv[2]) set expected $argv[3] echo "Expected $expected to not be $operator" case 4 set expected $argv[2] set operator "not" (assert.expand_operator $argv[3]) set actual $argv[4] echo "Expected $expected to $operator $actual" case \* return 1 end case \-\* test $number_of_arguments != 2; and return 1 set operator (assert.expand_operator $argv[1]) set expected $argv[2] echo "Expected $expected to be $operator" case \* test $number_of_arguments != 3; and return 1 set expected $argv[1] set operator (assert.expand_operator $argv[2]) set actual $argv[3] echo "Expected $expected to $operator $actual" end end