Source code in the jq programming language

def assert(exp; $msg):
  def m: $msg | if type == "string" then . else [.[]] | join(":") end;
  if env.JQ_ASSERT then
    (exp as $e | if $e then . else . as $in | "assertion violation @ \(m) => \($e)" | debug | $in end)
  else . end;

def assert(exp):
  if env.JQ_ASSERT then
    (exp as $e | if $e then . else . as $in | "assertion violation: \($e)" | debug | $in end)
   else . end;

def asserteq(x;y;$msg):
  def m: $msg | if type == "string" then . else [.[]] | join(":") end;
  def s: (if $msg then m + ": " else "" end) + "\(x) != \(y)";
  if env.JQ_ASSERT then
     if x == y then .
     else . as $in | "assertion violation @ \(s)" | debug | $in
     end
   else . end;

# File: example.jq
# This example assumes the availability of the $__loc__ function
# and that assert.jq is in the same directory as example.jq.

include "assert" {search: "."};

def test:
  "This is an input"
  | 0 as $x
  | assert($x == 42; $__loc__),
    asserteq($x; 42; $__loc__);

test