hide_positions_in_string does line-based regexp matching to replace line numbers and column numbers that appear in source-code positions with constant text LINE and COL. This can be useful in making displayed test output less fragile.

hide_temp_files_in_string replaces .tmp.______, where each _ represents some alphanumeric character, with ".tmp.RANDOM". This can make output deterministic when describing temporary files generated by, e.g., Core_unix.mkstemp.

Renders an s-expression as a string. With ~hide_positions:true, patterns in the string that match OCaml-style file positions are modified to hide the line number, column number, and character positions, to make output less fragile.

Substitutes with_ for every occurrence of pattern in a string.

Like replace, for every atom in a sexp.

Applies f at every node in the given sexp, top-down, recurring on the contents of the output. The word "smash" is used as in the sexp command-line tool's query language. See: https://github.com/janestreet/sexp

Removes OCaml backtraces from sexps.

For printing an s-expression to stdout. hide_positions works as in sexp_to_string.

Behaves like [%expect.output].

print_cr here message prints a CR require-failed, which will appear in expect-test output. The CR will appear in the feature owner's fe todo, thus preventing release of the feature. print_cr is an expect-test-friendly version of assert false. It works with the normal expect-test workflow because it does not raise, and it prevents mistakenly releasing features that violate a required property. There is no need to 'X' a CR require-failed; simply fix the property that triggered the print_cr and re-run the test to restore the empty output.

require here bool is a no-op if bool = true, but if not, prints a CR require-failed similarly to print_cr, with a message determined by the if_false_then_print_s argument, if any.

if_false_then_print_s is useful for including information that may help debug the problem, but that would otherwise be too voluminous. if_false_then_print_s is lazy to avoid construction of the sexp except when needed.

require_equal compares its two arguments using the equality predicate of the provided module. If the comparison fails, prints a message that renders the arguments as sexps.

Like require_equal, but derives an equality predicate from a comparison function.

Like require_equal, but when equality fails produces a message including sexps of both Set.diff first second and Set.diff second first to aid in debugging.

show_raise calls f () and prints the exception that it raises, or, if it doesn't raise, prints did not raise. show_raise ignores the result of f so that one doesn't have to put an ignore inside the body of an f that is expected to raise. ~hide_positions:true operates as in print_s, to make output less fragile. Using ~show_backtrace:true will result in a CR in the expectation, but it's still available here as it is still valuable when initially writing tests and debugging.

require_does_not_raise is like show_raise, but does not print anything if the function does not raise, and prints a CR along with the exception if it does raise. Unlike for show_raise, the supplied function is required to return unit to avoid mistakes like incomplete partial application that silently would not raise, but for the wrong reason.

require_does_raise is like show_raise, but additionally prints a CR if the function does not raise.

require_some here option is like require here (is_some option), with improved output. If option = None, it prints a CR. If option = Some some and ~print_some is provided, it prints print_some some.

require_none here sexp_of_some option is like require here (is_none option), with improved output. If option = Some some, it prints a CR including sexp_of_some some. If option = None, it does not print.

require_ok here or_error is like require here (is_ok or_error), with improved output. If or_error = Error error, it prints a CR including error. If or_error = Ok ok and ~print_ok is provided, it prints print_ok ok.

require_error here sexp_of_ok or_error is like require here (is_error or_error), with improved output. If or_error = Ok ok, it prints a CR including sexp_of_ok ok. If or_error = Error error and print_error = true, it prints error.

require_ok_result here sexp_of_error result is like require here (is_ok or_error), with improved output. If result = Error error, it prints a CR including sexp_of_error error. If result = Ok ok and ~print_ok is provided, it prints print_ok ok.

require_error_result here sexp_of_ok result is like require here (is_error result), with improved output. If result = Ok ok, it prints a CR including sexp_of_ok ok. If result = Error error and ~print_error is supplied, it prints print_error error.

require_first here print_second either is like require here (is_first either), with improved output. If either = Second second, it prints a CR including sexp_of_second second. If either = First first and ~print_first is provided, it prints print_first first.

require_second here sexp_of_first either is like require here (is_second either), with improved output. If either = First first, it prints a CR including sexp_of_first first. If either = Second second and ~print_second is provided, it prints print_second second.

quickcheck is similar to Base_quickcheck.Test.run, but

1. quickcheck takes separate arguments for the values which Base_quickcheck.Test.run takes in a first-class module.

2. quickcheck stops after the first iteration that raises or prints a CR, as detected by on_print_cr.

quickcheck_m is similar to Base_quickcheck.Test.run. It stops after the first iteration that raises or prints a CR, as detected by on_print_cr.

sexp_style determines the sexp format used by sexp_to_string, print_s, and other functions in this module. Defaults to Sexp_style.default_pretty.

on_print_cr determines the behavior of all functions above that print CRs, such as print_cr and require. The rendered string form of the CR is passed to !on_print_cr. The default value is print_endline; this can be overridden to replace or extend the default behavior. For example, some testing harnesses may choose to abort a series of tests after the first CR is printed.