More default options for filter

[lentinj]

The filter options flip through a string representation of an object until it finds one that doesn't match:

unittest/R/ut_cmp.R

Lines 20 to 31 in cf19036

	for (f in list(
	# Add any custom filtering function
	filter,
	# Strings can be compared directly using writeLines
	ifelse(is.character(a) && is.character(b), writeLines, 'ignore'),
	# Convert environments to list, print that
	ifelse(is.environment(a) && is.environment(b), function (x) print(as.list(x)), 'ignore'),
	# print will pick up any generics defined for custom types
	print,
	# Fall back to parsing with str
	function (x) utils::str(x, vec.len = 1000, digits.d = 5, nchar.max = 1000),
	NULL)) {

The theory was it should end with multiple str calls, increasing length / accuracy until it generates output that is different. Something like:-

    function (x) utils::str(x, vec.len = 1000, digits.d = 5, nchar.max =
1000),
   function (x) utils::str(x, vec.len = 1e10, digits.d = 10, nchar.max =
1e10),
   function (x) utils::str(x, vec.len = 1e20, digits.d =
.Machine$double.digits, nchar.max = 1e20),