xref: /frameworks/minikin/tests/unittest/LayoutUtilsTest.cpp

/*
 * Copyright (C) 2015 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 <gtest/gtest.h>
#include <UnicodeUtils.h>

#include "LayoutUtils.h"

namespace minikin {

void ExpectNextWordBreakForCache(size_t offset_in, const char* query_str) {
    const size_t BUF_SIZE = 256U;
    uint16_t buf[BUF_SIZE];
    size_t expected_breakpoint = 0U;
    size_t size = 0U;

    ParseUnicode(buf, BUF_SIZE, query_str, &size, &expected_breakpoint);
    EXPECT_EQ(expected_breakpoint,
              getNextWordBreakForCache(buf, offset_in, size))
        << "Expected position is [" << query_str << "] from offset " << offset_in;
}

void ExpectPrevWordBreakForCache(size_t offset_in, const char* query_str) {
    const size_t BUF_SIZE = 256U;
    uint16_t buf[BUF_SIZE];
    size_t expected_breakpoint = 0U;
    size_t size = 0U;

    ParseUnicode(buf, BUF_SIZE, query_str, &size, &expected_breakpoint);
    EXPECT_EQ(expected_breakpoint,
              getPrevWordBreakForCache(buf, offset_in, size))
        << "Expected position is [" << query_str << "] from offset " << offset_in;
}

TEST(WordBreakTest, goNextWordBreakTest) {
    ExpectNextWordBreakForCache(0, "|");

    // Continue for spaces.
    ExpectNextWordBreakForCache(0, "'a' 'b' 'c' 'd' |");
    ExpectNextWordBreakForCache(1, "'a' 'b' 'c' 'd' |");
    ExpectNextWordBreakForCache(2, "'a' 'b' 'c' 'd' |");
    ExpectNextWordBreakForCache(3, "'a' 'b' 'c' 'd' |");
    ExpectNextWordBreakForCache(4, "'a' 'b' 'c' 'd' |");
    ExpectNextWordBreakForCache(1000, "'a' 'b' 'c' 'd' |");

    // Space makes word break.
    ExpectNextWordBreakForCache(0, "'a' 'b' | U+0020 'c' 'd'");
    ExpectNextWordBreakForCache(1, "'a' 'b' | U+0020 'c' 'd'");
    ExpectNextWordBreakForCache(2, "'a' 'b' U+0020 | 'c' 'd'");
    ExpectNextWordBreakForCache(3, "'a' 'b' U+0020 'c' 'd' |");
    ExpectNextWordBreakForCache(4, "'a' 'b' U+0020 'c' 'd' |");
    ExpectNextWordBreakForCache(5, "'a' 'b' U+0020 'c' 'd' |");
    ExpectNextWordBreakForCache(1000, "'a' 'b' U+0020 'c' 'd' |");

    ExpectNextWordBreakForCache(0, "'a' 'b' | U+2000 'c' 'd'");
    ExpectNextWordBreakForCache(1, "'a' 'b' | U+2000 'c' 'd'");
    ExpectNextWordBreakForCache(2, "'a' 'b' U+2000 | 'c' 'd'");
    ExpectNextWordBreakForCache(3, "'a' 'b' U+2000 'c' 'd' |");
    ExpectNextWordBreakForCache(4, "'a' 'b' U+2000 'c' 'd' |");
    ExpectNextWordBreakForCache(5, "'a' 'b' U+2000 'c' 'd' |");
    ExpectNextWordBreakForCache(1000, "'a' 'b' U+2000 'c' 'd' |");

    ExpectNextWordBreakForCache(0, "'a' 'b' | U+2000 U+2000 'c' 'd'");
    ExpectNextWordBreakForCache(1, "'a' 'b' | U+2000 U+2000 'c' 'd'");
    ExpectNextWordBreakForCache(2, "'a' 'b' U+2000 | U+2000 'c' 'd'");
    ExpectNextWordBreakForCache(3, "'a' 'b' U+2000 U+2000 | 'c' 'd'");
    ExpectNextWordBreakForCache(4, "'a' 'b' U+2000 U+2000 'c' 'd' |");
    ExpectNextWordBreakForCache(5, "'a' 'b' U+2000 U+2000 'c' 'd' |");
    ExpectNextWordBreakForCache(6, "'a' 'b' U+2000 U+2000 'c' 'd' |");
    ExpectNextWordBreakForCache(1000, "'a' 'b' U+2000 U+2000 'c' 'd' |");

    // CJK ideographs makes word break.
    ExpectNextWordBreakForCache(0, "U+4E00 | U+4E00   U+4E00   U+4E00   U+4E00");
    ExpectNextWordBreakForCache(1, "U+4E00   U+4E00 | U+4E00   U+4E00   U+4E00");
    ExpectNextWordBreakForCache(2, "U+4E00   U+4E00   U+4E00 | U+4E00   U+4E00");
    ExpectNextWordBreakForCache(3, "U+4E00   U+4E00   U+4E00   U+4E00 | U+4E00");
    ExpectNextWordBreakForCache(4, "U+4E00   U+4E00   U+4E00   U+4E00   U+4E00 |");
    ExpectNextWordBreakForCache(5, "U+4E00   U+4E00   U+4E00   U+4E00   U+4E00 |");
    ExpectNextWordBreakForCache(1000,
                             "U+4E00   U+4E00   U+4E00   U+4E00   U+4E00 |");

    ExpectNextWordBreakForCache(0, "U+4E00 | U+4E8C   U+4E09   U+56DB   U+4E94");
    ExpectNextWordBreakForCache(1, "U+4E00   U+4E8C | U+4E09   U+56DB   U+4E94");
    ExpectNextWordBreakForCache(2, "U+4E00   U+4E8C   U+4E09 | U+56DB   U+4E94");
    ExpectNextWordBreakForCache(3, "U+4E00   U+4E8C   U+4E09   U+56DB | U+4E94");
    ExpectNextWordBreakForCache(4, "U+4E00   U+4E8C   U+4E09   U+56DB   U+4E94 |");
    ExpectNextWordBreakForCache(5, "U+4E00   U+4E8C   U+4E09   U+56DB   U+4E94 |");
    ExpectNextWordBreakForCache(1000,
                             "U+4E00   U+4E8C   U+4E09   U+56DB   U+4E94 |");

    ExpectNextWordBreakForCache(0, "U+4E00 'a' 'b' | U+2000 'c' U+4E00");
    ExpectNextWordBreakForCache(1, "U+4E00 'a' 'b' | U+2000 'c' U+4E00");
    ExpectNextWordBreakForCache(2, "U+4E00 'a' 'b' | U+2000 'c' U+4E00");
    ExpectNextWordBreakForCache(3, "U+4E00 'a' 'b' U+2000 | 'c' U+4E00");
    ExpectNextWordBreakForCache(4, "U+4E00 'a' 'b' U+2000 'c' | U+4E00");
    ExpectNextWordBreakForCache(5, "U+4E00 'a' 'b' U+2000 'c' U+4E00 |");
    ExpectNextWordBreakForCache(1000, "U+4E00 'a' 'b' U+2000 'c' U+4E00 |");

    // Continue if trailing characters is Unicode combining characters.
    ExpectNextWordBreakForCache(0, "U+4E00 U+0332 | U+4E00");
    ExpectNextWordBreakForCache(1, "U+4E00 U+0332 | U+4E00");
    ExpectNextWordBreakForCache(2, "U+4E00 U+0332 U+4E00 |");
    ExpectNextWordBreakForCache(3, "U+4E00 U+0332 U+4E00 |");
    ExpectNextWordBreakForCache(1000, "U+4E00 U+0332 U+4E00 |");

    // Surrogate pairs.
    ExpectNextWordBreakForCache(0, "U+1F60D U+1F618 |");
    ExpectNextWordBreakForCache(1, "U+1F60D U+1F618 |");
    ExpectNextWordBreakForCache(2, "U+1F60D U+1F618 |");
    ExpectNextWordBreakForCache(3, "U+1F60D U+1F618 |");
    ExpectNextWordBreakForCache(4, "U+1F60D U+1F618 |");
    ExpectNextWordBreakForCache(1000, "U+1F60D U+1F618 |");

    // Broken surrogate pairs.
    // U+D84D is leading surrogate but there is no trailing surrogate for it.
    ExpectNextWordBreakForCache(0, "U+D84D U+1F618 |");
    ExpectNextWordBreakForCache(1, "U+D84D U+1F618 |");
    ExpectNextWordBreakForCache(2, "U+D84D U+1F618 |");
    ExpectNextWordBreakForCache(3, "U+D84D U+1F618 |");
    ExpectNextWordBreakForCache(1000, "U+D84D U+1F618 |");

    ExpectNextWordBreakForCache(0, "U+1F618 U+D84D |");
    ExpectNextWordBreakForCache(1, "U+1F618 U+D84D |");
    ExpectNextWordBreakForCache(2, "U+1F618 U+D84D |");
    ExpectNextWordBreakForCache(3, "U+1F618 U+D84D |");
    ExpectNextWordBreakForCache(1000, "U+1F618 U+D84D |");

    // U+DE0D is trailing surrogate but there is no leading surrogate for it.
    ExpectNextWordBreakForCache(0, "U+DE0D U+1F618 |");
    ExpectNextWordBreakForCache(1, "U+DE0D U+1F618 |");
    ExpectNextWordBreakForCache(2, "U+DE0D U+1F618 |");
    ExpectNextWordBreakForCache(3, "U+DE0D U+1F618 |");
    ExpectNextWordBreakForCache(1000, "U+DE0D U+1F618 |");

    ExpectNextWordBreakForCache(0, "U+1F618 U+DE0D |");
    ExpectNextWordBreakForCache(1, "U+1F618 U+DE0D |");
    ExpectNextWordBreakForCache(2, "U+1F618 U+DE0D |");
    ExpectNextWordBreakForCache(3, "U+1F618 U+DE0D |");
    ExpectNextWordBreakForCache(1000, "U+1F618 U+DE0D |");

    // Regional indicator pair. U+1F1FA U+1F1F8 is US national flag.
    ExpectNextWordBreakForCache(0, "U+1F1FA U+1F1F8 |");
    ExpectNextWordBreakForCache(1, "U+1F1FA U+1F1F8 |");
    ExpectNextWordBreakForCache(2, "U+1F1FA U+1F1F8 |");
    ExpectNextWordBreakForCache(1000, "U+1F1FA U+1F1F8 |");

    // Tone marks.
    // CJK ideographic char + Tone mark + CJK ideographic char
    ExpectNextWordBreakForCache(0, "U+4444 U+302D | U+4444");
    ExpectNextWordBreakForCache(1, "U+4444 U+302D | U+4444");
    ExpectNextWordBreakForCache(2, "U+4444 U+302D U+4444 |");
    ExpectNextWordBreakForCache(3, "U+4444 U+302D U+4444 |");
    ExpectNextWordBreakForCache(1000, "U+4444 U+302D U+4444 |");

    // Variation Selectors.
    // CJK Ideographic char + Variation Selector(VS1) + CJK Ideographic char
    ExpectNextWordBreakForCache(0, "U+845B U+FE00 | U+845B");
    ExpectNextWordBreakForCache(1, "U+845B U+FE00 | U+845B");
    ExpectNextWordBreakForCache(2, "U+845B U+FE00 U+845B |");
    ExpectNextWordBreakForCache(3, "U+845B U+FE00 U+845B |");
    ExpectNextWordBreakForCache(1000, "U+845B U+FE00 U+845B |");

    // CJK Ideographic char + Variation Selector(VS17) + CJK Ideographic char
    ExpectNextWordBreakForCache(0, "U+845B U+E0100 | U+845B");
    ExpectNextWordBreakForCache(1, "U+845B U+E0100 | U+845B");
    ExpectNextWordBreakForCache(2, "U+845B U+E0100 | U+845B");
    ExpectNextWordBreakForCache(3, "U+845B U+E0100 U+845B |");
    ExpectNextWordBreakForCache(4, "U+845B U+E0100 U+845B |");
    ExpectNextWordBreakForCache(5, "U+845B U+E0100 U+845B |");
    ExpectNextWordBreakForCache(1000, "U+845B U+E0100 U+845B |");

    // CJK ideographic char + Tone mark + Variation Character(VS1)
    ExpectNextWordBreakForCache(0, "U+4444 U+302D U+FE00 | U+4444");
    ExpectNextWordBreakForCache(1, "U+4444 U+302D U+FE00 | U+4444");
    ExpectNextWordBreakForCache(2, "U+4444 U+302D U+FE00 | U+4444");
    ExpectNextWordBreakForCache(3, "U+4444 U+302D U+FE00 U+4444 |");
    ExpectNextWordBreakForCache(4, "U+4444 U+302D U+FE00 U+4444 |");
    ExpectNextWordBreakForCache(1000, "U+4444 U+302D U+FE00 U+4444 |");

    // CJK ideographic char + Tone mark + Variation Character(VS17)
    ExpectNextWordBreakForCache(0, "U+4444 U+302D U+E0100 | U+4444");
    ExpectNextWordBreakForCache(1, "U+4444 U+302D U+E0100 | U+4444");
    ExpectNextWordBreakForCache(2, "U+4444 U+302D U+E0100 | U+4444");
    ExpectNextWordBreakForCache(3, "U+4444 U+302D U+E0100 | U+4444");
    ExpectNextWordBreakForCache(4, "U+4444 U+302D U+E0100 U+4444 |");
    ExpectNextWordBreakForCache(5, "U+4444 U+302D U+E0100 U+4444 |");
    ExpectNextWordBreakForCache(1000, "U+4444 U+302D U+E0100 U+4444 |");

    // CJK ideographic char + Variation Character(VS1) + Tone mark
    ExpectNextWordBreakForCache(0, "U+4444 U+FE00 U+302D | U+4444");
    ExpectNextWordBreakForCache(1, "U+4444 U+FE00 U+302D | U+4444");
    ExpectNextWordBreakForCache(2, "U+4444 U+FE00 U+302D | U+4444");
    ExpectNextWordBreakForCache(3, "U+4444 U+FE00 U+302D U+4444 |");
    ExpectNextWordBreakForCache(4, "U+4444 U+FE00 U+302D U+4444 |");
    ExpectNextWordBreakForCache(1000, "U+4444 U+FE00 U+302D U+4444 |");

    // CJK ideographic char + Variation Character(VS17) + Tone mark
    ExpectNextWordBreakForCache(0, "U+4444 U+E0100 U+302D | U+4444");
    ExpectNextWordBreakForCache(1, "U+4444 U+E0100 U+302D | U+4444");
    ExpectNextWordBreakForCache(2, "U+4444 U+E0100 U+302D | U+4444");
    ExpectNextWordBreakForCache(3, "U+4444 U+E0100 U+302D | U+4444");
    ExpectNextWordBreakForCache(4, "U+4444 U+E0100 U+302D U+4444 |");
    ExpectNextWordBreakForCache(5, "U+4444 U+E0100 U+302D U+4444 |");
    ExpectNextWordBreakForCache(1000, "U+4444 U+E0100 U+302D U+4444 |");

    // Following test cases are unusual usage of variation selectors and tone
    // marks for caching up the further behavior changes, e.g. index of bounds
    // or crashes. Please feel free to update the test expectations if the
    // behavior change makes sense to you.

    // Isolated Tone marks and Variation Selectors
    ExpectNextWordBreakForCache(0, "U+FE00 |");
    ExpectNextWordBreakForCache(1, "U+FE00 |");
    ExpectNextWordBreakForCache(1000, "U+FE00 |");
    ExpectNextWordBreakForCache(0, "U+E0100 |");
    ExpectNextWordBreakForCache(1000, "U+E0100 |");
    ExpectNextWordBreakForCache(0, "U+302D |");
    ExpectNextWordBreakForCache(1000, "U+302D |");

    // CJK Ideographic char + Variation Selector(VS1) + Variation Selector(VS1)
    ExpectNextWordBreakForCache(0, "U+845B U+FE00 U+FE00 | U+845B");
    ExpectNextWordBreakForCache(1, "U+845B U+FE00 U+FE00 | U+845B");
    ExpectNextWordBreakForCache(2, "U+845B U+FE00 U+FE00 | U+845B");
    ExpectNextWordBreakForCache(3, "U+845B U+FE00 U+FE00 U+845B |");
    ExpectNextWordBreakForCache(4, "U+845B U+FE00 U+FE00 U+845B |");
    ExpectNextWordBreakForCache(1000, "U+845B U+FE00 U+FE00 U+845B |");

    // CJK Ideographic char + Variation Selector(VS17) + Variation Selector(VS17)
    ExpectNextWordBreakForCache(0, "U+845B U+E0100 U+E0100 | U+845B");
    ExpectNextWordBreakForCache(1, "U+845B U+E0100 U+E0100 | U+845B");
    ExpectNextWordBreakForCache(2, "U+845B U+E0100 U+E0100 | U+845B");
    ExpectNextWordBreakForCache(3, "U+845B U+E0100 U+E0100 | U+845B");
    ExpectNextWordBreakForCache(4, "U+845B U+E0100 U+E0100 | U+845B");
    ExpectNextWordBreakForCache(5, "U+845B U+E0100 U+E0100 U+845B |");
    ExpectNextWordBreakForCache(6, "U+845B U+E0100 U+E0100 U+845B |");
    ExpectNextWordBreakForCache(1000,
                             "U+845B U+E0100 U+E0100 U+845B |");

    // CJK Ideographic char + Variation Selector(VS1) + Variation Selector(VS17)
    ExpectNextWordBreakForCache(0, "U+845B U+FE00 U+E0100 | U+845B");
    ExpectNextWordBreakForCache(1, "U+845B U+FE00 U+E0100 | U+845B");
    ExpectNextWordBreakForCache(2, "U+845B U+FE00 U+E0100 | U+845B");
    ExpectNextWordBreakForCache(3, "U+845B U+FE00 U+E0100 | U+845B");
    ExpectNextWordBreakForCache(4, "U+845B U+FE00 U+E0100 U+845B |");
    ExpectNextWordBreakForCache(5, "U+845B U+FE00 U+E0100 U+845B |");
    ExpectNextWordBreakForCache(1000, "U+845B U+FE00 U+E0100 U+845B |");

    // CJK Ideographic char + Variation Selector(VS17) + Variation Selector(VS1)
    ExpectNextWordBreakForCache(0, "U+845B U+E0100 U+FE00 | U+845B");
    ExpectNextWordBreakForCache(1, "U+845B U+E0100 U+FE00 | U+845B");
    ExpectNextWordBreakForCache(2, "U+845B U+E0100 U+FE00 | U+845B");
    ExpectNextWordBreakForCache(3, "U+845B U+E0100 U+FE00 | U+845B");
    ExpectNextWordBreakForCache(4, "U+845B U+E0100 U+FE00 U+845B |");
    ExpectNextWordBreakForCache(5, "U+845B U+E0100 U+FE00 U+845B |");
    ExpectNextWordBreakForCache(1000, "U+845B U+E0100 U+FE00 U+845B |");

    // Tone mark. + Tone mark
    ExpectNextWordBreakForCache(0, "U+4444 U+302D U+302D | U+4444");
    ExpectNextWordBreakForCache(1, "U+4444 U+302D U+302D | U+4444");
    ExpectNextWordBreakForCache(2, "U+4444 U+302D U+302D | U+4444");
    ExpectNextWordBreakForCache(3, "U+4444 U+302D U+302D U+4444 |");
    ExpectNextWordBreakForCache(4, "U+4444 U+302D U+302D U+4444 |");
    ExpectNextWordBreakForCache(1000, "U+4444 U+302D U+302D U+4444 |");
}

TEST(WordBreakTest, goPrevWordBreakTest) {
    ExpectPrevWordBreakForCache(0, "|");

    // Continue for spaces.
    ExpectPrevWordBreakForCache(0, "| 'a' 'b' 'c' 'd'");
    ExpectPrevWordBreakForCache(1, "| 'a' 'b' 'c' 'd'");
    ExpectPrevWordBreakForCache(2, "| 'a' 'b' 'c' 'd'");
    ExpectPrevWordBreakForCache(3, "| 'a' 'b' 'c' 'd'");
    ExpectPrevWordBreakForCache(4, "| 'a' 'b' 'c' 'd'");
    ExpectPrevWordBreakForCache(1000, "| 'a' 'b' 'c' 'd'");

    // Space makes word break.
    ExpectPrevWordBreakForCache(0, "| 'a' 'b' U+0020 'c' 'd'");
    ExpectPrevWordBreakForCache(1, "| 'a' 'b' U+0020 'c' 'd'");
    ExpectPrevWordBreakForCache(2, "| 'a' 'b' U+0020 'c' 'd'");
    ExpectPrevWordBreakForCache(3, "'a' 'b' | U+0020 'c' 'd'");
    ExpectPrevWordBreakForCache(4, "'a' 'b' U+0020 | 'c' 'd'");
    ExpectPrevWordBreakForCache(5, "'a' 'b' U+0020 | 'c' 'd'");
    ExpectPrevWordBreakForCache(1000, "'a' 'b' U+0020 | 'c' 'd'");

    ExpectPrevWordBreakForCache(0, "| 'a' 'b' U+2000 'c' 'd'");
    ExpectPrevWordBreakForCache(1, "| 'a' 'b' U+2000 'c' 'd'");
    ExpectPrevWordBreakForCache(2, "| 'a' 'b' U+2000 'c' 'd'");
    ExpectPrevWordBreakForCache(3, "'a' 'b' | U+2000 'c' 'd'");
    ExpectPrevWordBreakForCache(4, "'a' 'b' U+2000 | 'c' 'd'");
    ExpectPrevWordBreakForCache(5, "'a' 'b' U+2000 | 'c' 'd'");
    ExpectPrevWordBreakForCache(1000, "'a' 'b' U+2000 | 'c' 'd'");

    ExpectPrevWordBreakForCache(0, "| 'a' 'b' U+2000 U+2000 'c' 'd'");
    ExpectPrevWordBreakForCache(1, "| 'a' 'b' U+2000 U+2000 'c' 'd'");
    ExpectPrevWordBreakForCache(2, "| 'a' 'b' U+2000 U+2000 'c' 'd'");
    ExpectPrevWordBreakForCache(3, "'a' 'b' | U+2000 U+2000 'c' 'd'");
    ExpectPrevWordBreakForCache(4, "'a' 'b' U+2000 | U+2000 'c' 'd'");
    ExpectPrevWordBreakForCache(5, "'a' 'b' U+2000 U+2000 | 'c' 'd'");
    ExpectPrevWordBreakForCache(6, "'a' 'b' U+2000 U+2000 | 'c' 'd'");
    ExpectPrevWordBreakForCache(1000, "'a' 'b' U+2000 U+2000 | 'c' 'd'");

    // CJK ideographs makes word break.
    ExpectPrevWordBreakForCache(0, "| U+4E00 U+4E00 U+4E00 U+4E00 U+4E00");
    ExpectPrevWordBreakForCache(1, "| U+4E00 U+4E00 U+4E00 U+4E00 U+4E00");
    ExpectPrevWordBreakForCache(2, "U+4E00 | U+4E00 U+4E00 U+4E00 U+4E00");
    ExpectPrevWordBreakForCache(3, "U+4E00 U+4E00 | U+4E00 U+4E00 U+4E00");
    ExpectPrevWordBreakForCache(4, "U+4E00 U+4E00 U+4E00 | U+4E00 U+4E00");
    ExpectPrevWordBreakForCache(5, "U+4E00 U+4E00 U+4E00 U+4E00 | U+4E00");
    ExpectPrevWordBreakForCache(1000, "U+4E00 U+4E00 U+4E00 U+4E00 | U+4E00");

    ExpectPrevWordBreakForCache(0, "| U+4E00 U+4E8C U+4E09 U+56DB U+4E94");
    ExpectPrevWordBreakForCache(1, "| U+4E00 U+4E8C U+4E09 U+56DB U+4E94");
    ExpectPrevWordBreakForCache(2, "U+4E00 | U+4E8C U+4E09 U+56DB U+4E94");
    ExpectPrevWordBreakForCache(3, "U+4E00 U+4E8C | U+4E09 U+56DB U+4E94");
    ExpectPrevWordBreakForCache(4, "U+4E00 U+4E8C U+4E09 | U+56DB U+4E94");
    ExpectPrevWordBreakForCache(5, "U+4E00 U+4E8C U+4E09 U+56DB | U+4E94");
    ExpectPrevWordBreakForCache(1000, "U+4E00 U+4E8C U+4E09 U+56DB | U+4E94");

    // Mixed case.
    ExpectPrevWordBreakForCache(0, "| U+4E00 'a' 'b' U+2000 'c' U+4E00");
    ExpectPrevWordBreakForCache(1, "| U+4E00 'a' 'b' U+2000 'c' U+4E00");
    ExpectPrevWordBreakForCache(2, "| U+4E00 'a' 'b' U+2000 'c' U+4E00");
    ExpectPrevWordBreakForCache(3, "| U+4E00 'a' 'b' U+2000 'c' U+4E00");
    ExpectPrevWordBreakForCache(4, "U+4E00 'a' 'b' | U+2000 'c' U+4E00");
    ExpectPrevWordBreakForCache(5, "U+4E00 'a' 'b' U+2000 | 'c' U+4E00");
    ExpectPrevWordBreakForCache(6, "U+4E00 'a' 'b' U+2000 'c' | U+4E00");
    ExpectPrevWordBreakForCache(1000, "U+4E00 'a' 'b' U+2000 'c' | U+4E00");

    // Continue if trailing characters is Unicode combining characters.
    ExpectPrevWordBreakForCache(0, "| U+4E00 U+0332 U+4E00");
    ExpectPrevWordBreakForCache(1, "| U+4E00 U+0332 U+4E00");
    ExpectPrevWordBreakForCache(2, "| U+4E00 U+0332 U+4E00");
    ExpectPrevWordBreakForCache(3, "U+4E00 U+0332 | U+4E00");
    ExpectPrevWordBreakForCache(1000, "U+4E00 U+0332 | U+4E00");

    // Surrogate pairs.
    ExpectPrevWordBreakForCache(0, "| U+1F60D U+1F618");
    ExpectPrevWordBreakForCache(1, "| U+1F60D U+1F618");
    ExpectPrevWordBreakForCache(2, "| U+1F60D U+1F618");
    ExpectPrevWordBreakForCache(3, "| U+1F60D U+1F618");
    ExpectPrevWordBreakForCache(4, "| U+1F60D U+1F618");
    ExpectPrevWordBreakForCache(1000, "| U+1F60D U+1F618");

    // Broken surrogate pairs.
    // U+D84D is leading surrogate but there is no trailing surrogate for it.
    ExpectPrevWordBreakForCache(0, "| U+D84D U+1F618");
    ExpectPrevWordBreakForCache(1, "| U+D84D U+1F618");
    ExpectPrevWordBreakForCache(2, "| U+D84D U+1F618");
    ExpectPrevWordBreakForCache(3, "| U+D84D U+1F618");
    ExpectPrevWordBreakForCache(1000, "| U+D84D U+1F618");

    ExpectPrevWordBreakForCache(0, "| U+1F618 U+D84D");
    ExpectPrevWordBreakForCache(1, "| U+1F618 U+D84D");
    ExpectPrevWordBreakForCache(2, "| U+1F618 U+D84D");
    ExpectPrevWordBreakForCache(3, "| U+1F618 U+D84D");
    ExpectPrevWordBreakForCache(1000, "| U+1F618 U+D84D");

    // U+DE0D is trailing surrogate but there is no leading surrogate for it.
    ExpectPrevWordBreakForCache(0, "| U+DE0D U+1F618");
    ExpectPrevWordBreakForCache(1, "| U+DE0D U+1F618");
    ExpectPrevWordBreakForCache(2, "| U+DE0D U+1F618");
    ExpectPrevWordBreakForCache(3, "| U+DE0D U+1F618");
    ExpectPrevWordBreakForCache(1000, "| U+DE0D U+1F618");

    ExpectPrevWordBreakForCache(0, "| U+1F618 U+DE0D");
    ExpectPrevWordBreakForCache(1, "| U+1F618 U+DE0D");
    ExpectPrevWordBreakForCache(2, "| U+1F618 U+DE0D");
    ExpectPrevWordBreakForCache(3, "| U+1F618 U+DE0D");
    ExpectPrevWordBreakForCache(1000, "| U+1F618 U+DE0D");

    // Regional indicator pair. U+1F1FA U+1F1F8 is US national flag.
    ExpectPrevWordBreakForCache(0, "| U+1F1FA U+1F1F8");
    ExpectPrevWordBreakForCache(1, "| U+1F1FA U+1F1F8");
    ExpectPrevWordBreakForCache(2, "| U+1F1FA U+1F1F8");
    ExpectPrevWordBreakForCache(1000, "| U+1F1FA U+1F1F8");

    // Tone marks.
    // CJK ideographic char + Tone mark + CJK ideographic char
    ExpectPrevWordBreakForCache(0, "| U+4444 U+302D U+4444");
    ExpectPrevWordBreakForCache(1, "| U+4444 U+302D U+4444");
    ExpectPrevWordBreakForCache(2, "| U+4444 U+302D U+4444");
    ExpectPrevWordBreakForCache(3, "U+4444 U+302D | U+4444");
    ExpectPrevWordBreakForCache(1000, "U+4444 U+302D | U+4444");

    // Variation Selectors.
    // CJK Ideographic char + Variation Selector(VS1) + CJK Ideographic char
    ExpectPrevWordBreakForCache(0, "| U+845B U+FE00 U+845B");
    ExpectPrevWordBreakForCache(1, "| U+845B U+FE00 U+845B");
    ExpectPrevWordBreakForCache(2, "| U+845B U+FE00 U+845B");
    ExpectPrevWordBreakForCache(3, "U+845B U+FE00 | U+845B");
    ExpectPrevWordBreakForCache(1000, "U+845B U+FE00 | U+845B");

    // CJK Ideographic char + Variation Selector(VS17) + CJK Ideographic char
    ExpectPrevWordBreakForCache(0, "| U+845B U+E0100 U+845B");
    ExpectPrevWordBreakForCache(1, "| U+845B U+E0100 U+845B");
    ExpectPrevWordBreakForCache(2, "| U+845B U+E0100 U+845B");
    ExpectPrevWordBreakForCache(3, "| U+845B U+E0100 U+845B");
    ExpectPrevWordBreakForCache(4, "U+845B U+E0100 | U+845B");
    ExpectPrevWordBreakForCache(5, "U+845B U+E0100 | U+845B");
    ExpectPrevWordBreakForCache(1000, "U+845B U+E0100 | U+845B");

    // CJK ideographic char + Tone mark + Variation Character(VS1)
    ExpectPrevWordBreakForCache(0, "| U+4444 U+302D U+FE00 U+4444");
    ExpectPrevWordBreakForCache(1, "| U+4444 U+302D U+FE00 U+4444");
    ExpectPrevWordBreakForCache(2, "| U+4444 U+302D U+FE00 U+4444");
    ExpectPrevWordBreakForCache(3, "| U+4444 U+302D U+FE00 U+4444");
    ExpectPrevWordBreakForCache(4, "U+4444 U+302D U+FE00 | U+4444");
    ExpectPrevWordBreakForCache(1000, "U+4444 U+302D U+FE00 | U+4444");

    // CJK ideographic char + Tone mark + Variation Character(VS17)
    ExpectPrevWordBreakForCache(0, "| U+4444 U+302D U+E0100 U+4444");
    ExpectPrevWordBreakForCache(1, "| U+4444 U+302D U+E0100 U+4444");
    ExpectPrevWordBreakForCache(2, "| U+4444 U+302D U+E0100 U+4444");
    ExpectPrevWordBreakForCache(3, "| U+4444 U+302D U+E0100 U+4444");
    ExpectPrevWordBreakForCache(4, "| U+4444 U+302D U+E0100 U+4444");
    ExpectPrevWordBreakForCache(5, "U+4444 U+302D U+E0100 | U+4444");
    ExpectPrevWordBreakForCache(1000, "U+4444 U+302D U+E0100 | U+4444");

    // CJK ideographic char + Variation Character(VS1) + Tone mark
    ExpectPrevWordBreakForCache(0, "| U+4444 U+FE00 U+302D U+4444");
    ExpectPrevWordBreakForCache(1, "| U+4444 U+FE00 U+302D U+4444");
    ExpectPrevWordBreakForCache(2, "| U+4444 U+FE00 U+302D U+4444");
    ExpectPrevWordBreakForCache(3, "| U+4444 U+FE00 U+302D U+4444");
    ExpectPrevWordBreakForCache(4, "U+4444 U+FE00 U+302D | U+4444");
    ExpectPrevWordBreakForCache(1000, "U+4444 U+FE00 U+302D | U+4444");

    // CJK ideographic char + Variation Character(VS17) + Tone mark
    ExpectPrevWordBreakForCache(0, "| U+4444 U+E0100 U+302D U+4444");
    ExpectPrevWordBreakForCache(1, "| U+4444 U+E0100 U+302D U+4444");
    ExpectPrevWordBreakForCache(2, "| U+4444 U+E0100 U+302D U+4444");
    ExpectPrevWordBreakForCache(3, "| U+4444 U+E0100 U+302D U+4444");
    ExpectPrevWordBreakForCache(4, "| U+4444 U+E0100 U+302D U+4444");
    ExpectPrevWordBreakForCache(5, "U+4444 U+E0100 U+302D | U+4444");
    ExpectPrevWordBreakForCache(1000, "U+4444 U+E0100 U+302D | U+4444");

    // Following test cases are unusual usage of variation selectors and tone
    // marks for caching up the further behavior changes, e.g. index of bounds
    // or crashes. Please feel free to update the test expectations if the
    // behavior change makes sense to you.

    // Isolated Tone marks and Variation Selectors
    ExpectPrevWordBreakForCache(0, "| U+FE00");
    ExpectPrevWordBreakForCache(1, "| U+FE00");
    ExpectPrevWordBreakForCache(1000, "| U+FE00");
    ExpectPrevWordBreakForCache(0, "| U+E0100");
    ExpectPrevWordBreakForCache(1000, "| U+E0100");
    ExpectPrevWordBreakForCache(0, "| U+302D");
    ExpectPrevWordBreakForCache(1000, "| U+302D");

    // CJK Ideographic char + Variation Selector(VS1) + Variation Selector(VS1)
    ExpectPrevWordBreakForCache(0, "| U+845B U+FE00 U+FE00 U+845B");
    ExpectPrevWordBreakForCache(1, "| U+845B U+FE00 U+FE00 U+845B");
    ExpectPrevWordBreakForCache(2, "| U+845B U+FE00 U+FE00 U+845B");
    ExpectPrevWordBreakForCache(3, "| U+845B U+FE00 U+FE00 U+845B");
    ExpectPrevWordBreakForCache(4, "U+845B U+FE00 U+FE00 | U+845B");
    ExpectPrevWordBreakForCache(1000, "U+845B U+FE00 U+FE00 | U+845B");

    // CJK Ideographic char + Variation Selector(VS17) + Variation Selector(VS17)
    ExpectPrevWordBreakForCache(0, "| U+845B U+E0100 U+E0100 U+845B");
    ExpectPrevWordBreakForCache(1, "| U+845B U+E0100 U+E0100 U+845B");
    ExpectPrevWordBreakForCache(2, "| U+845B U+E0100 U+E0100 U+845B");
    ExpectPrevWordBreakForCache(3, "| U+845B U+E0100 U+E0100 U+845B");
    ExpectPrevWordBreakForCache(4, "| U+845B U+E0100 U+E0100 U+845B");
    ExpectPrevWordBreakForCache(5, "| U+845B U+E0100 U+E0100 U+845B");
    ExpectPrevWordBreakForCache(6, "U+845B U+E0100 U+E0100 | U+845B");
    ExpectPrevWordBreakForCache(1000,
                             "U+845B U+E0100 U+E0100 | U+845B");

    // CJK Ideographic char + Variation Selector(VS1) + Variation Selector(VS17)
    ExpectPrevWordBreakForCache(0, "| U+845B U+FE00 U+E0100 U+845B");
    ExpectPrevWordBreakForCache(1, "| U+845B U+FE00 U+E0100 U+845B");
    ExpectPrevWordBreakForCache(2, "| U+845B U+FE00 U+E0100 U+845B");
    ExpectPrevWordBreakForCache(3, "| U+845B U+FE00 U+E0100 U+845B");
    ExpectPrevWordBreakForCache(4, "| U+845B U+FE00 U+E0100 U+845B");
    ExpectPrevWordBreakForCache(5, "U+845B U+FE00 U+E0100 | U+845B");
    ExpectPrevWordBreakForCache(1000, "U+845B U+FE00 U+E0100 | U+845B");

    // CJK Ideographic char + Variation Selector(VS17) + Variation Selector(VS1)
    ExpectPrevWordBreakForCache(0, "| U+845B U+E0100 U+FE00 U+845B");
    ExpectPrevWordBreakForCache(1, "| U+845B U+E0100 U+FE00 U+845B");
    ExpectPrevWordBreakForCache(2, "| U+845B U+E0100 U+FE00 U+845B");
    ExpectPrevWordBreakForCache(3, "| U+845B U+E0100 U+FE00 U+845B");
    ExpectPrevWordBreakForCache(4, "| U+845B U+E0100 U+FE00 U+845B");
    ExpectPrevWordBreakForCache(5, "U+845B U+E0100 U+FE00 | U+845B");
    ExpectPrevWordBreakForCache(1000, "U+845B U+E0100 U+FE00 | U+845B");

    // Tone mark. + Tone mark
    ExpectPrevWordBreakForCache(0, "| U+4444 U+302D U+302D U+4444");
    ExpectPrevWordBreakForCache(1, "| U+4444 U+302D U+302D U+4444");
    ExpectPrevWordBreakForCache(2, "| U+4444 U+302D U+302D U+4444");
    ExpectPrevWordBreakForCache(3, "| U+4444 U+302D U+302D U+4444");
    ExpectPrevWordBreakForCache(4, "U+4444 U+302D U+302D | U+4444");
    ExpectPrevWordBreakForCache(1000, "U+4444 U+302D U+302D | U+4444");
}

}  // namespace minikin