error rewriting spec

moonscript/errors.lua

@@ -107,5 +107,6 @@ end
 return {
   rewrite_traceback = rewrite_traceback,
   truncate_traceback = truncate_traceback,
-  user_error = user_error
+  user_error = user_error,
+  reverse_line_number = reverse_line_number
 }

moonscript/errors.moon

@@ -84,5 +84,5 @@ rewrite_traceback = (text, err) ->
   }, "\n"
 
 
-{ :rewrite_traceback, :truncate_traceback, :user_error }
+{ :rewrite_traceback, :truncate_traceback, :user_error, :reverse_line_number }
 

spec/error_inputs/first.moon

@@ -1,6 +1,8 @@
 
 hello_world = false
 
+print = ->
+
 if hello_world
   print "sackman"
   x = 5 + 5

spec/error_inputs/second.moon

@@ -1,4 +1,5 @@
 
+print = ->
 
 if false
   true

spec/error_inputs/third.moon

@@ -1,4 +1,6 @@
 
+print = ->
+
 if (->
   print "hello world"
   print "who is this")

spec/error_rewriting_spec.moon

@@ -0,0 +1,30 @@
+
+moonscript = require "moonscript.base"
+errors = require "moonscript.errors"
+util = require "moonscript.util"
+
+get_rewritten_line_no = (fname) ->
+  fname = "spec/error_inputs/#{fname}.moon"
+  chunk = moonscript.loadfile fname
+
+  success, err = pcall chunk
+  error "`#{fname}` is supposed to have runtime error!" if success
+
+  source = tonumber err\match "]:(%d+)"
+
+  line_table = require("moonscript.line_tables")[fname]
+  errors.reverse_line_number fname, line_table, source, {}
+
+
+-- TODO: check entire stack trace
+describe "error rewriting", ->
+  tests = {
+    "first": 24
+    "second": 16
+    "third": 11
+  }
+
+  for name, expected_no in pairs tests
+    it "should rewrite line number", ->
+      assert.same get_rewritten_line_no(name), expected_no
+