Add converting subsonic api Lyrics entity to domain entity.

Signed-off-by: Yahor Berdnikau <egorr.berd@gmail.com>

ultrasonic/src/main/kotlin/org/moire/ultrasonic/data/APILyricsConverter.kt

@@ -0,0 +1,13 @@
+// Converts Lyrics entity from [org.moire.ultrasonic.api.subsonic.SubsonicAPIClient]
+// to app domain entities.
+@file:JvmName("APILyricsConverter")
+package org.moire.ultrasonic.data
+
+import org.moire.ultrasonic.domain.Lyrics
+import org.moire.ultrasonic.api.subsonic.models.Lyrics as APILyrics
+
+fun APILyrics.toDomainEntity(): Lyrics = Lyrics().apply {
+    artist = this@toDomainEntity.artist
+    title = this@toDomainEntity.title
+    text = this@toDomainEntity.text
+}

ultrasonic/src/test/kotlin/org/moire/ultrasonic/data/APILyricsConverterTest.kt

@@ -0,0 +1,25 @@
+@file:Suppress("IllegalIdentifier")
+
+package org.moire.ultrasonic.data
+
+import org.amshove.kluent.`should equal to`
+import org.junit.Test
+import org.moire.ultrasonic.api.subsonic.models.Lyrics
+
+/**
+ * Unit test for extension functions in [APILyricsConverter.kt] file.
+ */
+class APILyricsConverterTest {
+    @Test
+    fun `Should convert Lyrics entity to domain`() {
+        val entity = Lyrics(artist = "some-artist", title = "some-title", text = "song-text")
+
+        val convertedEntity = entity.toDomainEntity()
+
+        with(convertedEntity) {
+            artist `should equal to` entity.artist
+            title `should equal to` entity.title
+            text `should equal to` entity.text
+        }
+    }
+}