Migrate to shared class hierarchy for unit based database tests.

app/src/test/java/org/thoughtcrime/securesms/testutil/SignalDatabaseRule.kt

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2025 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.testutil
+
+import androidx.sqlite.db.SupportSQLiteDatabase
+import androidx.sqlite.db.SupportSQLiteOpenHelper
+import androidx.sqlite.db.framework.FrameworkSQLiteOpenHelperFactory
+import androidx.test.core.app.ApplicationProvider
+import io.mockk.every
+import io.mockk.mockkObject
+import io.mockk.unmockkObject
+import org.junit.rules.ExternalResource
+import org.thoughtcrime.securesms.database.SQLiteDatabase
+import org.thoughtcrime.securesms.database.SignalDatabase
+import org.thoughtcrime.securesms.testing.TestSignalDatabase
+
+class SignalDatabaseRule : ExternalResource() {
+
+  lateinit var signalDatabase: TestSignalDatabase
+
+  val readableDatabase: SQLiteDatabase
+    get() = signalDatabase.signalReadableDatabase
+
+  val writeableDatabase: SQLiteDatabase
+    get() = signalDatabase.signalWritableDatabase
+
+  override fun before() {
+    signalDatabase = inMemorySignalDatabase()
+
+    mockkObject(SignalDatabase)
+    every { SignalDatabase.instance } returns signalDatabase
+  }
+
+  override fun after() {
+    unmockkObject(SignalDatabase)
+    signalDatabase.close()
+  }
+
+  companion object {
+    /**
+     * Create an in-memory only database mimicking one created fresh for Signal. This includes
+     * all non-FTS tables, indexes, and triggers.
+     */
+    private fun inMemorySignalDatabase(): TestSignalDatabase {
+      val configuration = SupportSQLiteOpenHelper.Configuration(
+        context = ApplicationProvider.getApplicationContext(),
+        name = "test",
+        callback = object : SupportSQLiteOpenHelper.Callback(1) {
+          override fun onCreate(db: SupportSQLiteDatabase) = Unit
+          override fun onUpgrade(db: SupportSQLiteDatabase, oldVersion: Int, newVersion: Int) = Unit
+        },
+        useNoBackupDirectory = false,
+        allowDataLossOnRecovery = true
+      )
+
+      val helper = FrameworkSQLiteOpenHelperFactory().create(configuration)
+      val signalDatabase = TestSignalDatabase(ApplicationProvider.getApplicationContext(), helper)
+      signalDatabase.onCreateTablesIndexesAndTriggers(signalDatabase.signalWritableDatabase)
+
+      return signalDatabase
+    }
+  }
+}