test: setup :common:android for testing

Otherwise it's easy to forget to add it to androidModulesToUnitTest

Assisted-by: Claude Opus 4.6 - tests

Author: david-allison

AnkiDroid/jacoco.gradle

@@ -127,7 +127,7 @@ tasks.register('jacocoTestReport', JacocoReport) {
 }
 
 // Android library modules (do not yet support flavors play/full)
-def androidModulesToUnitTest = [":libanki", ":compat"]
+def androidModulesToUnitTest = [":common:android", ":libanki", ":compat"]
 // JVM modules: use 'test' task and 'classes/kotlin/main' class dir
 def jvmModulesToUnitTest = [":common"]
 

common/android/build.gradle.kts

@@ -60,4 +60,10 @@ dependencies {
 
     implementation(libs.androidx.annotation)
     implementation(libs.jakewharton.timber)
+
+    testImplementation(libs.kotlin.test)
+    testImplementation(libs.junit.jupiter)
+    testImplementation(libs.junit.vintage.engine)
+    testImplementation(libs.robolectric)
+    testImplementation(libs.androidx.test.junit)
 }

common/android/src/test/java/com/ichi2/anki/common/utils/android/ColorUtilsTest.kt

@@ -0,0 +1,45 @@
+/*
+ *  Copyright (c) 2026 David Allison <davidallisongithub@gmail.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify it under
+ *  the terms of the GNU General Public License as published by the Free Software
+ *  Foundation; either version 3 of the License, or (at your option) any later
+ *  version.
+ *
+ *  This program is distributed in the hope that it will be useful, but WITHOUT ANY
+ *  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ *  PARTICULAR PURPOSE. See the GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with
+ *  this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.ichi2.anki.common.utils.android
+
+import android.graphics.Color
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.Test
+import org.junit.runner.RunWith
+import kotlin.test.assertEquals
+
+/** Tests for [darkenColor] and [lightenColorAbsolute] */
+@RunWith(AndroidJUnit4::class)
+class ColorUtilsTest {
+    @Test
+    fun darkenColor_withNoChange_returnsSameColor() {
+        val white = Color.WHITE
+        assertEquals(white, darkenColor(white, factor = 1.0f))
+    }
+
+    @Test
+    fun darkenColor_withFullDarken_returnsBlack() {
+        val white = Color.WHITE
+        assertEquals(Color.BLACK, darkenColor(white, factor = 0.0f))
+    }
+
+    @Test
+    fun lightenColorAbsolute_withNoChange_returnsSameColor() {
+        val red = Color.RED
+        assertEquals(red, lightenColorAbsolute(red, amount = 0.0f))
+    }
+}