native/utils/strings/utf8_test.cc

/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "utils/strings/utf8.h"

#include "gmock/gmock.h"
#include "gtest/gtest.h"

namespace libtextclassifier3 {
namespace {

TEST(Utf8Test, ComputesUtf8LengthOfUnicodeCharacters) {
  EXPECT_EQ(GetNumBytesForUTF8Char("\x00"), 1);
  EXPECT_EQ(GetNumBytesForUTF8Char("h"), 1);
  EXPECT_EQ(GetNumBytesForUTF8Char("😋"), 4);
  EXPECT_EQ(GetNumBytesForUTF8Char("㍿"), 3);
}

TEST(Utf8Test, IsValidUTF8) {
  EXPECT_TRUE(IsValidUTF8("1234😋hello", 13));
  EXPECT_TRUE(IsValidUTF8("\u304A\u00B0\u106B", 8));
  EXPECT_TRUE(IsValidUTF8("this is a test😋😋😋", 26));
  EXPECT_TRUE(IsValidUTF8("\xf0\x9f\x98\x8b", 4));
  // Example with first byte payload of zero.
  EXPECT_TRUE(IsValidUTF8("\xf0\x90\x80\x80", 4));
  // Too short (string is too short).
  EXPECT_FALSE(IsValidUTF8("\xf0\x9f", 2));
  // Too long (too many trailing bytes).
  EXPECT_FALSE(IsValidUTF8("\xf0\x9f\x98\x8b\x8b", 5));
  // Too short (too few trailing bytes).
  EXPECT_FALSE(IsValidUTF8("\xf0\x9f\x98\x61\x61", 5));
  // Invalid continuation byte (can be encoded in less bytes).
  EXPECT_FALSE(IsValidUTF8("\xc0\x81", 2));
  // Invalid continuation byte (can be encoded in less bytes).
  EXPECT_FALSE(IsValidUTF8("\xf0\x8a\x85\x8f", 4));
}

TEST(Utf8Test, CorrectlyTruncatesStrings) {
  EXPECT_EQ(SafeTruncateLength("FooBar", 3), 3);
  EXPECT_EQ(SafeTruncateLength("früh", 3), 2);
  EXPECT_EQ(SafeTruncateLength("مَمِمّمَّمِّ", 5), 4);
}

TEST(Utf8Test, CorrectlyConvertsFromUtf8) {
  EXPECT_EQ(ValidCharToRune("a"), 97);
  EXPECT_EQ(ValidCharToRune("\0"), 0);
  EXPECT_EQ(ValidCharToRune("\u304A"), 0x304a);
  EXPECT_EQ(ValidCharToRune("\xe3\x81\x8a"), 0x304a);
}

TEST(Utf8Test, CorrectlyConvertsToUtf8) {
  char utf8_encoding[4];
  EXPECT_EQ(ValidRuneToChar(97, utf8_encoding), 1);
  EXPECT_EQ(ValidRuneToChar(0, utf8_encoding), 1);
  EXPECT_EQ(ValidRuneToChar(0x304a, utf8_encoding), 3);
}

}  // namespace
}  // namespace libtextclassifier3