removeForbiddenCharactersFromFileName() + tests

FileNameUtils.kt

import org.junit.Test
import kotlin.test.assertEquals
import kotlin.test.assertTrue

object FileNameUtils {

    private const val forbiddenFileNameCharsRegexp = "([\\\\<>:?\"*|/])"

    fun removeForbiddenCharactersFromFileName(fileName: String): String {
        return fileName.replace(forbiddenFileNameCharsRegexp.toRegex(), "")
    }
}

class FileNameUtilsTest {

    private val forbiddenChars = "<>:?\"*|/"

    @Test
    fun `when given file name then removed forbidden characters`() {
        assertNoForbiddenCharacters("123abc!@#", "123abc!@#")
        assertNoForbiddenCharacters("a${forbiddenChars}b", "ab")
        assertNoForbiddenCharacters("//ab//", "ab")
        assertNoForbiddenCharacters("/ab/", "ab")
        assertNoForbiddenCharacters("""\ab\"""", "ab")
        assertNoForbiddenCharacters("""\\a\\b\\"""", "ab")
        assertNoForbiddenCharacters("*ab*", "ab")
        assertNoForbiddenCharacters(":ab:", "ab")
        assertNoForbiddenCharacters("<ab>", "ab")
        assertNoForbiddenCharacters("?ab?", "ab")
        assertNoForbiddenCharacters("|a|b|", "ab")
        assertNoForbiddenCharacters("|||", "")
    }

    private fun assertNoForbiddenCharacters(originalFileName: String, expectedFileName: String) {
        val correctFileName = FileUtils.removeForbiddenCharactersFromFileName(originalFileName)
        forbiddenChars.forEach { char ->
            assertTrue("File name $originalFileName contains $char character") {
                !correctFileName.contains(char)
            }
        }
        assertEquals(expectedFileName, correctFileName)
    }
}