DataConnectCacheDatabaseMigrator.kt, DataConnectCacheDatabaseMigratorUnitTest.kt: Improve user_version error message and add tests

The error message for an invalid `user_version` in `DataConnectCacheDatabaseMigrator` was improved to include the version number in both decimal and hexadecimal formats. This provides more context for debugging.

Additionally, unit tests were added to `DataConnectCacheDatabaseMigratorUnitTest` to verify the behavior of the `user_version` migration. These tests cover setting the `user_version` in a new database, ensuring it remains unchanged if already correct, and verifying that an exception is thrown for invalid versions.

### Changes
* DataConnectCacheDatabaseMigrator.kt:
    * Updated `InvalidUserVersionException` to include the `user_version` in both decimal and hexadecimal formats.
    * Removed an unnecessary type check when reading the schema version from the database.
* DataConnectCacheDatabaseMigratorUnitTest.kt:
    * Added a test to ensure `InvalidUserVersionException` is thrown for invalid `user_version` values and that the error message is correct.
    * Added a test to verify that `user_version` is set correctly in a new database.
    * Added a test to verify that `user_version` is not changed if it is already correct.

Author: dconeybe

firebase-dataconnect/src/main/kotlin/com/google/firebase/dataconnect/sqlite2/DataConnectCacheDatabaseMigrator.kt

@@ -17,7 +17,6 @@
 package com.google.firebase.dataconnect.sqlite2
 
 import android.annotation.SuppressLint
-import android.database.Cursor
 import android.database.sqlite.SQLiteDatabase
 import com.google.firebase.dataconnect.core.Logger
 import com.google.firebase.dataconnect.core.LoggerGlobals.debug
@@ -140,8 +139,11 @@ private constructor(private val sqliteDatabase: SQLiteDatabase, private val logg
         RunMigrationStepResult.StepExecuted(newSchemaVersion = "1.0.0")
       }
       else -> {
-        logger.debug { "user_version $userVersion is unsupported; aborting" }
-        throw InvalidUserVersionException("user_version is $userVersion, but expected 0 or 1")
+        throw InvalidUserVersionException(
+          "user_version $userVersion (${userVersion.to0xHexString()}) is unknown;" +
+            " expected 0 or 1;" +
+            " aborting to avoid corrupting the contents of the database"
+        )
       }
     }
   }
@@ -150,7 +152,7 @@ private constructor(private val sqliteDatabase: SQLiteDatabase, private val logg
     val schemaVersion: String? =
       sqliteDatabase.rawQuery(logger, "SELECT text FROM metadata WHERE name = 'schema_version'") {
         cursor ->
-        if (cursor.moveToNext() && cursor.getType(0) == Cursor.FIELD_TYPE_STRING) {
+        if (cursor.moveToNext()) {
           cursor.getString(0)
         } else {
           null

firebase-dataconnect/src/test/kotlin/com/google/firebase/dataconnect/sqlite2/DataConnectCacheDatabaseMigratorUnitTest.kt

@@ -18,6 +18,7 @@ package com.google.firebase.dataconnect.sqlite2
 
 import com.google.firebase.dataconnect.core.Logger
 import com.google.firebase.dataconnect.sqlite2.DataConnectCacheDatabaseMigrator.InvalidApplicationIdException
+import com.google.firebase.dataconnect.sqlite2.DataConnectCacheDatabaseMigrator.InvalidUserVersionException
 import com.google.firebase.dataconnect.sqlite2.SQLiteDatabaseExts.getApplicationId
 import com.google.firebase.dataconnect.sqlite2.SQLiteDatabaseExts.setApplicationId
 import com.google.firebase.dataconnect.testutil.DataConnectLogLevelRule
@@ -111,6 +112,55 @@ class DataConnectCacheDatabaseMigratorUnitTest {
     }
   }
 
+  @Test
+  fun `migrate() user_version should set the value in a new database`() {
+    val mockLogger: Logger = mockk(relaxed = true)
+    val userVersion =
+      DataConnectSQLiteDatabaseOpener.open(dbFile, mockLogger).use { db ->
+        DataConnectCacheDatabaseMigrator.migrate(db, mockLogger)
+        db.version
+      }
+    userVersion shouldBe 1
+  }
+
+  @Test
+  fun `migrate() user_version should leave value alone if already correct`() {
+    val mockLogger: Logger = mockk(relaxed = true)
+    val userVersion =
+      DataConnectSQLiteDatabaseOpener.open(dbFile, mockLogger).use { db ->
+        DataConnectCacheDatabaseMigrator.migrate(db, mockLogger)
+        DataConnectCacheDatabaseMigrator.migrate(db, mockLogger)
+        db.version
+      }
+    userVersion shouldBe 1
+  }
+
+  @Test
+  fun `migrate() user_version should throw if the value is invalid`() = runTest {
+    checkAll(propTestConfig, Arb.int()) { userVersion ->
+      assume(userVersion != 0 && userVersion != 1)
+      val mockLogger: Logger = mockk(relaxed = true)
+
+      val exception =
+        DataConnectSQLiteDatabaseOpener.open(null, mockLogger).use { db ->
+          db.version = userVersion
+          shouldThrow<InvalidUserVersionException> {
+            DataConnectCacheDatabaseMigrator.migrate(db, mockLogger)
+          }
+        }
+
+      assertSoftly {
+        exception.message shouldContainWithNonAbuttingText "user_version"
+        exception.message shouldContainWithNonAbuttingText "0"
+        exception.message shouldContainWithNonAbuttingText "1"
+        exception.message shouldContainWithNonAbuttingTextIgnoringCase userVersion.to0xHexString()
+        exception.message shouldContainWithNonAbuttingText userVersion.toString()
+        exception.message shouldContainWithNonAbuttingTextIgnoringCase "unknown"
+        exception.message shouldContainWithNonAbuttingTextIgnoringCase "aborting"
+      }
+    }
+  }
+
   private companion object {
 
     @OptIn(ExperimentalKotest::class)