add tests for component registrar

Author: demolaf

auth/src/test/java/com/firebase/ui/auth/FirebaseUIComposeRegistrarTest.kt

@@ -0,0 +1,104 @@
+/*
+ * Copyright 2025 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.firebase.ui.auth
+
+import android.content.Context
+import android.content.pm.PackageManager
+import androidx.test.core.app.ApplicationProvider
+import com.google.common.truth.Truth.assertThat
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+
+/**
+ * Unit tests for [FirebaseUIComposeRegistrar] covering component registration
+ * and AndroidManifest.xml configuration validation.
+ */
+@RunWith(RobolectricTestRunner::class)
+@Config(sdk = [28])
+class FirebaseUIComposeRegistrarTest {
+
+    private lateinit var context: Context
+    private lateinit var registrar: FirebaseUIComposeRegistrar
+
+    @Before
+    fun setUp() {
+        context = ApplicationProvider.getApplicationContext()
+        registrar = FirebaseUIComposeRegistrar()
+    }
+
+    // =============================================================================================
+    // Component Registration Tests
+    // =============================================================================================
+
+    @Test
+    fun `getComponents() returns exactly one component`() {
+        val components = registrar.getComponents()
+
+        assertThat(components).hasSize(1)
+    }
+
+    // =============================================================================================
+    // AndroidManifest.xml Configuration Tests
+    // =============================================================================================
+
+    @Test
+    fun `ComponentDiscoveryService has correct meta-data for FirebaseUIComposeRegistrar`() {
+        val packageInfo = context.packageManager.getPackageInfo(
+            context.packageName,
+            PackageManager.GET_SERVICES or PackageManager.GET_META_DATA
+        )
+
+        val service = packageInfo.services?.find { serviceInfo ->
+            serviceInfo.name == "com.google.firebase.components.ComponentDiscoveryService"
+        }
+
+        assertThat(service).isNotNull()
+
+        val metaData = service?.metaData
+        assertThat(metaData).isNotNull()
+
+        // Check the meta-data key contains the fully qualified class name
+        val expectedMetaDataKey = "com.google.firebase.components:com.firebase.ui.auth.FirebaseUIComposeRegistrar"
+        val metaDataValue = metaData?.getString(expectedMetaDataKey)
+
+        assertThat(metaDataValue).isEqualTo("com.google.firebase.components.ComponentRegistrar")
+    }
+
+    // =============================================================================================
+    // Class Metadata Tests
+    // =============================================================================================
+
+    @Test
+    fun `meta-data key matches actual class fully qualified name`() {
+        // The expected meta-data key format used in AndroidManifest.xml
+        val expectedMetaDataKey = "com.google.firebase.components:com.firebase.ui.auth.FirebaseUIComposeRegistrar"
+        val actualClassName = FirebaseUIComposeRegistrar::class.java.name
+
+        // Extract the class name from the meta-data key (after the colon)
+        val classNameInMetaData = expectedMetaDataKey.substringAfter(":")
+
+        assertThat(classNameInMetaData).isEqualTo(actualClassName)
+    }
+
+    @Test
+    fun `registrar implements ComponentRegistrar interface`() {
+        val interfaces = FirebaseUIComposeRegistrar::class.java.interfaces
+
+        assertThat(interfaces.map { it.name }).contains("com.google.firebase.components.ComponentRegistrar")
+    }
+}