Rename spec -> test

'Test' is a lot more straightforward of a name.

test/helpers/encoding_helpers.cc

@@ -0,0 +1,58 @@
+#include "helpers/encoding_helpers.h"
+#include "runtime/utf16.h"
+#include <assert.h>
+#include "utf8proc.h"
+
+static inline int string_iterate(TSInputEncoding encoding, const uint8_t *string, size_t length, int32_t *code_point) {
+  if (encoding == TSInputEncodingUTF8)
+    return utf8proc_iterate(string, length, code_point);
+  else
+    return utf16_iterate(string, length, code_point);
+}
+
+size_t string_char_count(TSInputEncoding encoding, const std::string &input) {
+  const char *string = input.data();
+  size_t size = input.size();
+  size_t character = 0, byte = 0;
+
+  while (byte < size) {
+    int32_t code_point;
+    byte += string_iterate(encoding, (uint8_t *)string + byte, size - byte, &code_point);
+    character++;
+  }
+
+  return character;
+}
+
+long string_byte_for_character(TSInputEncoding encoding, const std::string &input, size_t byte_offset, size_t goal_character) {
+  const char *string = input.data() + byte_offset;
+  size_t size = input.size() - byte_offset;
+  size_t character = 0, byte = 0;
+
+  while (character < goal_character) {
+    if (byte >= size)
+      return -1;
+
+    int32_t code_point;
+    byte += string_iterate(encoding, (uint8_t *)string + byte, size - byte, &code_point);
+    character++;
+  }
+
+  return byte;
+}
+
+size_t utf8_char_count(const std::string &input) {
+  return string_char_count(TSInputEncodingUTF8, input);
+}
+
+size_t utf16_char_count(const std::string &input) {
+  return string_char_count(TSInputEncodingUTF16, input);
+}
+
+long utf8_byte_for_character(const std::string &input, size_t byte_offset, size_t goal_character) {
+  return string_byte_for_character(TSInputEncodingUTF8, input, byte_offset, goal_character);
+}
+
+long utf16_byte_for_character(const std::string &input, size_t byte_offset, size_t goal_character) {
+  return string_byte_for_character(TSInputEncodingUTF16, input, byte_offset, goal_character);
+}