skylarktest/assert.sky

# Predeclared built-ins for this module:
#
# error(msg): report an error in Go's test framework without halting execution.
# catch(f): evaluate f() and returns its evaluation error message, if any
# matches(str, pattern): report whether str matches regular expression pattern.
# struct: a constructor for a simple HasFields implementation.
# _freeze(x): freeze the value x and everything reachable from it.
#
# Clients may use these functions to define their own testing abstractions.

def _eq(x, y):
  if x != y:
    error("%r != %r" % (x, y))

def _ne(x, y):
  if x == y:
    error("%r == %r" % (x, y))

def _true(cond, msg="assertion failed"):
  if not cond:
    error(msg)

def _lt(x, y):
  if not (x < y):
    error("%s is not less than %s" % (x, y))

def _contains(x, y):
  if y not in x:
    error("%s does not contain %s" % (x, y))

def _fails(f, pattern):
  "assert_fails asserts that evaluation of f() fails with the specified error."
  msg = catch(f)
  if msg == None:
      error("evaluation succeeded unexpectedly (want error matching %r)" % pattern)
  elif not matches(pattern, msg):
      error("regular expression (%s) did not match error (%s)" % (pattern, msg))

freeze = _freeze # an exported global whose value is the built-in freeze function

assert = struct(
    fail = error,
    eq = _eq,
    ne = _ne,
    true = _true,
    lt = _lt,
    contains = _contains,
    fails = _fails,
)