test(US-11): add failing tests for settings persistence

app/build.gradle.kts

@@ -55,6 +55,7 @@ dependencies {
     implementation(libs.lifecycle.viewmodel.compose)
 
     testImplementation(libs.junit)
+    testImplementation(libs.mockito.kotlin)
     androidTestImplementation(libs.androidx.junit)
     androidTestImplementation(libs.androidx.espresso.core)
     androidTestImplementation(platform(libs.androidx.compose.bom))

app/src/test/kotlin/net/jeena/pacer/SettingsRepositoryTest.kt

@@ -0,0 +1,79 @@
+package net.jeena.pacer
+
+import android.content.Context
+import android.content.SharedPreferences
+import org.junit.Assert.assertEquals
+import org.junit.Before
+import org.junit.Test
+import org.mockito.kotlin.any
+import org.mockito.kotlin.eq
+import org.mockito.kotlin.mock
+import org.mockito.kotlin.verify
+import org.mockito.kotlin.whenever
+
+class SettingsRepositoryTest {
+
+    private lateinit var prefs: SharedPreferences
+    private lateinit var editor: SharedPreferences.Editor
+    private lateinit var context: Context
+    private lateinit var repo: SettingsRepository
+
+    @Before
+    fun setUp() {
+        editor = mock()
+        whenever(editor.putInt(any(), any())).thenReturn(editor)
+        whenever(editor.putFloat(any(), any())).thenReturn(editor)
+
+        prefs = mock()
+        whenever(prefs.edit()).thenReturn(editor)
+        whenever(prefs.getInt(eq(SettingsRepository.KEY_BPM), any())).thenReturn(120)
+        whenever(prefs.getFloat(eq(SettingsRepository.KEY_VOLUME), any())).thenReturn(1f)
+
+        context = mock()
+        whenever(context.getSharedPreferences(any(), any())).thenReturn(prefs)
+
+        repo = SettingsRepository(context)
+    }
+
+    @Test
+    fun `saveBpm writes to shared preferences`() {
+        repo.saveBpm(130)
+        verify(editor).putInt(SettingsRepository.KEY_BPM, 130)
+        verify(editor).apply()
+    }
+
+    @Test
+    fun `saveVolume writes to shared preferences`() {
+        repo.saveVolume(0.7f)
+        verify(editor).putFloat(SettingsRepository.KEY_VOLUME, 0.7f)
+        verify(editor).apply()
+    }
+
+    @Test
+    fun `loadBpm returns stored value`() {
+        whenever(prefs.getInt(eq(SettingsRepository.KEY_BPM), any())).thenReturn(130)
+        assertEquals(130, repo.loadBpm())
+    }
+
+    @Test
+    fun `loadVolume returns stored value`() {
+        whenever(prefs.getFloat(eq(SettingsRepository.KEY_VOLUME), any())).thenReturn(0.5f)
+        assertEquals(0.5f, repo.loadVolume())
+    }
+
+    @Test
+    fun `loadBpm returns default 120 when nothing saved`() {
+        whenever(prefs.getInt(eq(SettingsRepository.KEY_BPM), any())).thenAnswer {
+            it.getArgument(1) as Int
+        }
+        assertEquals(120, repo.loadBpm())
+    }
+
+    @Test
+    fun `loadVolume returns default 1f when nothing saved`() {
+        whenever(prefs.getFloat(eq(SettingsRepository.KEY_VOLUME), any())).thenAnswer {
+            it.getArgument(1) as Float
+        }
+        assertEquals(1f, repo.loadVolume())
+    }
+}