Sample tests for TitleSortComparator

TitleSortComparator.kt

package io.github.mattpvaughn.chronicle.features.library

// src/main/java/io/github/mattpvaughn/chronicle/features/library/TitleSortComparator.kt

/** Compares Book titles using numerical ordering */
class TitleSortComparator {

    fun compare(bookTitle1: String, bookTitle2: String): Int {
        fun titleToArray(bookTitle: String): List<String> {
            return bookTitle.split(Regex("(?<=\\D)(?=\\d)|(?<=\\d)(?=\\D)"))
        }

        val title1: Iterator<String> = titleToArray(bookTitle1).iterator()
        val title2: Iterator<String> = titleToArray(bookTitle2).iterator()

        while (true) {
            val bool1: Boolean = title1.hasNext()
            val bool2: Boolean = title2.hasNext()
            if (!(bool1 || bool2)) {
                return 0
            }
            if (!bool1) return -1
            if (!bool2) return 1

            val next1: String = title1.next()
            val next2: String = title2.next()

            try {
                if (next1.toInt() > next2.toInt())
                    return 1
                else if (next1.toInt() < next2.toInt())
                    return -1
            } catch (e: NumberFormatException) {
                val comp: Int = next1.compareTo(next2)
                if (comp != 0) return comp
            }
        }
    }

}

TitleSortComparatorTest.kt

package io.github.mattpvaughn.chronicle.features.library

import org.junit.Assert.assertEquals
import org.junit.Test

// src/test/java/io/github/mattpvaughn/chronicle/features/library/TitleSortComparatorTest.kt
class TitleSortComparatorTest {

    private val titleSortComparator = TitleSortComparator()

    @Test
    fun `lower digit comes before higher digit`() {
        "1".assertComesBefore("2")
    }

    @Test
    fun `lower character comes before higher character`() {
        "a".assertComesBefore("b")
    }

    private fun String.assertComesBefore(other: String) {
        assertEquals(
            -1,
            titleSortComparator.compare(this, other)
        )
    }
}