colour letter placeholders by name and seed artwork themes from them

app/src/test/kotlin/com/subtracks/ui/theme/ArtworkColorsTest.kt

@@ -3,6 +3,7 @@ package com.subtracks.ui.theme
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.luminance
 import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotEquals
 import org.junit.Assert.assertTrue
 import org.junit.Test
 
@@ -27,6 +28,14 @@ class ArtworkColorsTest {
         }
     }
 
+    @Test
+    fun placeholderColourDependsOnTheNameAndIsNotGrey() {
+        assertEquals(0, placeholderSeed(""))
+        assertNotEquals(placeholderSeed("Kid A"), placeholderSeed("Amnesiac"))
+        val (_, saturation, _) = Color(placeholderSeed("Kid A")).toHsl()
+        assertTrue("placeholder should carry colour", saturation > 0f)
+    }
+
     @Test
     fun independentOfAlphaBits() {
         assertEquals(

app/src/test/kotlin/com/subtracks/ui/theme/ArtworkExtractionTest.kt

@@ -77,6 +77,18 @@ class ArtworkExtractionTest {
         assertTrue(colors!!.scheme.background.luminance() < 0.1f)
     }
 
+    @Test
+    fun fallsBackToAPlaceholderColourWhenThereIsNoArt() {
+        var colors: ArtworkColors? = null
+        composeRule.setContent {
+            SubtracksTheme {
+                colors = rememberArtworkColors(null, fallbackName = "Kid A")
+            }
+        }
+        composeRule.waitForIdle()
+        assertEquals(artworkColorsFromSeed(placeholderSeed("Kid A")).scheme.primary, colors?.scheme?.primary)
+    }
+
     @Test
     fun keepsContentStateWhenArtworkArrives() {
         val artwork = mutableStateOf<ArtworkColors?>(null)