Add testing setup

src/parser/parser.nim

@@ -194,6 +194,11 @@ proc endOfStream*(parser: Parser): ParserResult =
       parser: parser,
     ))
 
+proc newline*(parser: Parser): ParserResult =
+  parser
+  .endOfStream()
+  .flatMap(ch(NewLines))
+
 func ignore*(parserFn: Parser -> ParserResult): (Parser -> ParserResult) {.inline.} =
   ## Parse characters but throw success tokens away
   return proc(parser: Parser): ParserResult =
@@ -321,18 +326,32 @@ proc foldBuilder*[T, T2](
     let err = builderResult.error()
     onError(err[1])
 
+
 when isMainModule:
+  proc getTokens(x: ParserResult): seq[char] =
+    x.foldTokens(
+      proc(err: ParserError): seq[char] = @[],
+      proc(xs: seq[Token]): seq[char] = xs.map((x: Token) => x.value),
+    )
+
+  proc testParser(x: string, ps: seq[Parser -> ParserResult]): seq[char] =
+    initParserResult(x).parseSeq(ps).getTokens()
+
   let optionalPrefixParser = @[
     optional(ch('_')),
     str("ABC")
   ]
+  assert: "_ABC".testParser(optionalPrefixParser) == @['_', 'A', 'B', 'C']
+  assert: "ABC".testParser(optionalPrefixParser) == @['A', 'B', 'C']
 
-  echo initParserResult("_ABC").parseSeq(optionalPrefixParser)
-  echo initParserResult("ABC").parseSeq(optionalPrefixParser)
-
-  let andParsers = @[
+  let andParser = @[
     (ch('A') + ch('B')),
     ch('C'),
   ]
+  assert: "ABC".testParser(andParser) == @['A', 'B', 'C']
 
-  echo initParserResult("ABC").parseSeq(andParsers)
+  # let newlineParser = @[
+  #   str("ABC"),
+  #   newline
+  # ]
+  # echo initParserResult("ABC").parseSeq(newLineParser)