diff --git a/core/build.gradle b/core/build.gradle
index 16d8815d7..96deb0782 100644
--- a/core/build.gradle
+++ b/core/build.gradle
@@ -53,6 +53,7 @@ kotlin {
         commonMain {
             dependencies {
                 implementation kotlin('stdlib-common')
+                implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core-common:1.2.0-alpha-2'
             }
         }
 
@@ -66,6 +67,7 @@ kotlin {
         jvmMain {
             dependencies {
                 implementation kotlin('stdlib-jdk8')
+                implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.2.0-alpha-2'
             }
         }
 
@@ -80,6 +82,7 @@ kotlin {
         jsMain {
             dependencies {
                 implementation kotlin('stdlib-js')
+                implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core-js:1.2.0-alpha-2'
             }
         }
 
diff --git a/core/src/commonMain/kotlin/org/isoron/platform/io/Database.kt b/core/src/commonMain/kotlin/org/isoron/platform/io/Database.kt
index 047ec370c..7b6c33a77 100644
--- a/core/src/commonMain/kotlin/org/isoron/platform/io/Database.kt
+++ b/core/src/commonMain/kotlin/org/isoron/platform/io/Database.kt
@@ -80,7 +80,7 @@ fun Database.getVersion() = queryInt("pragma user_version")
 
 fun Database.setVersion(v: Int) = run("pragma user_version = $v")
 
-fun Database.migrateTo(newVersion: Int, fileOpener: FileOpener, log: Log) {
+suspend fun Database.migrateTo(newVersion: Int, fileOpener: FileOpener, log: Log) {
     val currentVersion = getVersion()
     log.debug("Database", "Current database version: $currentVersion")
 
@@ -92,9 +92,11 @@ fun Database.migrateTo(newVersion: Int, fileOpener: FileOpener, log: Log) {
     
     begin()
     for (v in (currentVersion + 1)..newVersion) {
-        val filename = sprintf("migrations/%03d.sql", v)
+        val sv = if(v < 10) "00$v" else if (v<100) "0$v" else "$v"
+        val filename = "migrations/$sv.sql"
+        println(filename)
         val migrationFile = fileOpener.openResourceFile(filename)
-        for (line in migrationFile.readLines()) {
+        for (line in migrationFile.lines()) {
             if (line.isEmpty()) continue
             run(line)
         }
diff --git a/core/src/commonMain/kotlin/org/isoron/platform/io/Files.kt b/core/src/commonMain/kotlin/org/isoron/platform/io/Files.kt
index 5be53ee5e..71a038cd5 100644
--- a/core/src/commonMain/kotlin/org/isoron/platform/io/Files.kt
+++ b/core/src/commonMain/kotlin/org/isoron/platform/io/Files.kt
@@ -56,6 +56,6 @@ interface UserFile {
  * files or translations. These files cannot be deleted.
  */
 interface ResourceFile {
-    fun readLines(): List<String>
     fun copyTo(dest: UserFile)
+    suspend fun lines(): List<String>
 }
\ No newline at end of file
diff --git a/core/src/commonMain/kotlin/org/isoron/platform/io/Log.kt b/core/src/commonMain/kotlin/org/isoron/platform/io/Log.kt
index cc59eb6c9..e8c0a10d3 100644
--- a/core/src/commonMain/kotlin/org/isoron/platform/io/Log.kt
+++ b/core/src/commonMain/kotlin/org/isoron/platform/io/Log.kt
@@ -29,11 +29,11 @@ interface Log {
  */
 class StandardLog : Log {
     override fun info(tag: String, msg: String) {
-        println(sprintf("I/%-20s %s", tag, msg))
+        println("I/$tag $msg")
     }
 
     override fun debug(tag: String, msg: String) {
-        println(sprintf("D/%-20s %s", tag, msg))
+        println("D/$tag $msg")
     }
 
 }
\ No newline at end of file
diff --git a/core/src/commonMain/kotlin/org/isoron/uhabits/backend/Backend.kt b/core/src/commonMain/kotlin/org/isoron/uhabits/backend/Backend.kt
index a81fb37f3..5b6142162 100644
--- a/core/src/commonMain/kotlin/org/isoron/uhabits/backend/Backend.kt
+++ b/core/src/commonMain/kotlin/org/isoron/uhabits/backend/Backend.kt
@@ -26,82 +26,82 @@ import org.isoron.uhabits.components.*
 import org.isoron.uhabits.i18n.*
 import org.isoron.uhabits.models.*
 
-class Backend(databaseName: String,
-              databaseOpener: DatabaseOpener,
-              fileOpener: FileOpener,
-              localeHelper: LocaleHelper,
-              val log: Log,
-              val taskRunner: TaskRunner) {
-
-    val database: Database
-
-    val habitsRepository: HabitRepository
-
-    val checkmarkRepository: CheckmarkRepository
-
-    val habits = mutableMapOf<Int, Habit>()
-
-    val checkmarks = mutableMapOf<Habit, CheckmarkList>()
-
-    val scores = mutableMapOf<Habit, ScoreList>()
-
-    val mainScreenDataSource: MainScreenDataSource
-
-    val strings = localeHelper.getStringsForCurrentLocale()
-
-    val preferences: Preferences
-
-    var theme: Theme = LightTheme()
-
-    init {
-        val dbFile = fileOpener.openUserFile(databaseName)
-        if (!dbFile.exists()) {
-            val templateFile = fileOpener.openResourceFile("databases/template.db")
-            templateFile.copyTo(dbFile)
-        }
-        database = databaseOpener.open(dbFile)
-        database.migrateTo(LOOP_DATABASE_VERSION, fileOpener, log)
-        preferences = Preferences(PreferencesRepository(database))
-        habitsRepository = HabitRepository(database)
-        checkmarkRepository = CheckmarkRepository(database)
-        taskRunner.runInBackground {
-            habits.putAll(habitsRepository.findAll())
-            for ((key, habit) in habits) {
-                val checks = checkmarkRepository.findAll(key)
-                checkmarks[habit] = CheckmarkList(habit.frequency, habit.type)
-                checkmarks[habit]?.setManualCheckmarks(checks)
-                scores[habit] = ScoreList(checkmarks[habit]!!)
-            }
-        }
-        mainScreenDataSource = MainScreenDataSource(preferences,
-                                                    habits,
-                                                    checkmarks,
-                                                    scores,
-                                                    taskRunner)
-    }
-
-    fun createHabit(habit: Habit) {
-        val id = habitsRepository.nextId()
-        habit.id = id
-        habit.position = habits.size
-        habits[id] = habit
-        checkmarks[habit] = CheckmarkList(habit.frequency, habit.type)
-        habitsRepository.insert(habit)
-        mainScreenDataSource.requestData()
-    }
-
-    fun deleteHabit(id: Int) {
-        habits[id]?.let { habit ->
-            habitsRepository.delete(habit)
-            habits.remove(id)
-            mainScreenDataSource.requestData()
-        }
-    }
-
-    fun updateHabit(modified: Habit) {
-        habits[modified.id]?.let { existing ->
-            modified.position = existing.position
-            habitsRepository.update(modified)
-        }
-    }
-}
+//class Backend(databaseName: String,
+//              databaseOpener: DatabaseOpener,
+//              fileOpener: FileOpener,
+//              localeHelper: LocaleHelper,
+//              val log: Log,
+//              val taskRunner: TaskRunner) {
+//
+//    val database: Database
+//
+//    val habitsRepository: HabitRepository
+//
+//    val checkmarkRepository: CheckmarkRepository
+//
+//    val habits = mutableMapOf<Int, Habit>()
+//
+//    val checkmarks = mutableMapOf<Habit, CheckmarkList>()
+//
+//    val scores = mutableMapOf<Habit, ScoreList>()
+//
+//    val mainScreenDataSource: MainScreenDataSource
+//
+//    val strings = localeHelper.getStringsForCurrentLocale()
+//
+//    val preferences: Preferences
+//
+//    var theme: Theme = LightTheme()
+//
+//    init {
+//        val dbFile = fileOpener.openUserFile(databaseName)
+//        if (!dbFile.exists()) {
+//            val templateFile = fileOpener.openResourceFile("databases/template.db")
+//            templateFile.copyTo(dbFile)
+//        }
+//        database = databaseOpener.open(dbFile)
+//        database.migrateTo(LOOP_DATABASE_VERSION, fileOpener, log)
+//        preferences = Preferences(PreferencesRepository(database))
+//        habitsRepository = HabitRepository(database)
+//        checkmarkRepository = CheckmarkRepository(database)
+//        taskRunner.runInBackground {
+//            habits.putAll(habitsRepository.findAll())
+//            for ((key, habit) in habits) {
+//                val checks = checkmarkRepository.findAll(key)
+//                checkmarks[habit] = CheckmarkList(habit.frequency, habit.type)
+//                checkmarks[habit]?.setManualCheckmarks(checks)
+//                scores[habit] = ScoreList(checkmarks[habit]!!)
+//            }
+//        }
+//        mainScreenDataSource = MainScreenDataSource(preferences,
+//                                                    habits,
+//                                                    checkmarks,
+//                                                    scores,
+//                                                    taskRunner)
+//    }
+//
+//    fun createHabit(habit: Habit) {
+//        val id = habitsRepository.nextId()
+//        habit.id = id
+//        habit.position = habits.size
+//        habits[id] = habit
+//        checkmarks[habit] = CheckmarkList(habit.frequency, habit.type)
+//        habitsRepository.insert(habit)
+//        mainScreenDataSource.requestData()
+//    }
+//
+//    fun deleteHabit(id: Int) {
+//        habits[id]?.let { habit ->
+//            habitsRepository.delete(habit)
+//            habits.remove(id)
+//            mainScreenDataSource.requestData()
+//        }
+//    }
+//
+//    fun updateHabit(modified: Habit) {
+//        habits[modified.id]?.let { existing ->
+//            modified.position = existing.position
+//            habitsRepository.update(modified)
+//        }
+//    }
+//}
diff --git a/core/src/commonTest/kotlin/org/isoron/BaseTest.kt b/core/src/commonTest/kotlin/org/isoron/BaseTest.kt
index e2b608bac..6ad312e82 100644
--- a/core/src/commonTest/kotlin/org/isoron/BaseTest.kt
+++ b/core/src/commonTest/kotlin/org/isoron/BaseTest.kt
@@ -22,5 +22,4 @@ package org.isoron
 open class BaseTest {
     val resolver = DependencyResolver()
     val fileOpener = resolver.getFileOpener()
-    val db = resolver.getDatabase()
 }
\ No newline at end of file
diff --git a/core/src/commonTest/kotlin/org/isoron/DependencyResolver.kt b/core/src/commonTest/kotlin/org/isoron/DependencyResolver.kt
index ae521f931..739bebacf 100644
--- a/core/src/commonTest/kotlin/org/isoron/DependencyResolver.kt
+++ b/core/src/commonTest/kotlin/org/isoron/DependencyResolver.kt
@@ -24,7 +24,7 @@ import org.isoron.platform.io.*
 
 expect class DependencyResolver() {
     fun getFileOpener(): FileOpener
-    fun getDatabase(): Database
+    suspend fun getDatabase(): Database
     fun createCanvas(width: Int, height: Int): Canvas
     fun exportCanvas(canvas: Canvas, filename: String)
 }
\ No newline at end of file
diff --git a/core/src/commonTest/kotlin/org/isoron/platform/io/DatabaseTest.kt b/core/src/commonTest/kotlin/org/isoron/platform/io/DatabaseTest.kt
index e3849f0b1..a9101995b 100644
--- a/core/src/commonTest/kotlin/org/isoron/platform/io/DatabaseTest.kt
+++ b/core/src/commonTest/kotlin/org/isoron/platform/io/DatabaseTest.kt
@@ -23,8 +23,8 @@ import org.isoron.*
 import kotlin.test.*
 
 class DatabaseTest() : BaseTest() {
-    @Test
-    fun testUsage() {
+    suspend fun testUsage() {
+        val db = resolver.getDatabase()
         db.setVersion(0)
         assertEquals(0, db.getVersion())
 
diff --git a/core/src/commonTest/kotlin/org/isoron/platform/io/FilesTest.kt b/core/src/commonTest/kotlin/org/isoron/platform/io/FilesTest.kt
index 7b3e5c01a..6532f4b09 100644
--- a/core/src/commonTest/kotlin/org/isoron/platform/io/FilesTest.kt
+++ b/core/src/commonTest/kotlin/org/isoron/platform/io/FilesTest.kt
@@ -23,15 +23,14 @@ import org.isoron.*
 import kotlin.test.*
 
 class FilesTest() : BaseTest() {
-    @Test
-    fun testReadLines() {
+    suspend fun testLines() {
         val hello = fileOpener.openResourceFile("hello.txt")
-        var lines = hello.readLines()
+        var lines = hello.lines()
         assertEquals("Hello World!", lines[0])
         assertEquals("This is a resource.", lines[1])
 
         val migration = fileOpener.openResourceFile("migrations/012.sql")
-        lines = migration.readLines()
+        lines = migration.lines()
         assertEquals("delete from Score", lines[0])
     }
 }
\ No newline at end of file
diff --git a/core/src/commonTest/kotlin/org/isoron/uhabits/models/CheckmarkRepositoryTest.kt b/core/src/commonTest/kotlin/org/isoron/uhabits/models/CheckmarkRepositoryTest.kt
index 8e225e260..57f9d94ea 100644
--- a/core/src/commonTest/kotlin/org/isoron/uhabits/models/CheckmarkRepositoryTest.kt
+++ b/core/src/commonTest/kotlin/org/isoron/uhabits/models/CheckmarkRepositoryTest.kt
@@ -25,8 +25,8 @@ import kotlin.test.*
 
 
 class CheckmarkRepositoryTest : BaseTest() {
-    @Test
-    fun testCRUD() {
+    suspend fun testCRUD() {
+        val db = resolver.getDatabase()
         val habitA = 10
         var checkmarksA = listOf(Checkmark(LocalDate(2019, 1, 15), 100),
                                  Checkmark(LocalDate(2019, 1, 7), 500),
diff --git a/core/src/commonTest/kotlin/org/isoron/uhabits/models/HabitRepositoryTest.kt b/core/src/commonTest/kotlin/org/isoron/uhabits/models/HabitRepositoryTest.kt
index ab733c790..09060b189 100644
--- a/core/src/commonTest/kotlin/org/isoron/uhabits/models/HabitRepositoryTest.kt
+++ b/core/src/commonTest/kotlin/org/isoron/uhabits/models/HabitRepositoryTest.kt
@@ -25,52 +25,43 @@ import org.isoron.platform.io.*
 import kotlin.test.*
 
 class HabitRepositoryTest() : BaseTest() {
+    suspend fun testCRUD() {
+        val db = resolver.getDatabase()
+        val original0 = Habit(id = 0,
+                              name = "Wake up early",
+                              description = "Did you wake up before 6am?",
+                              frequency = Frequency(1, 1),
+                              color = PaletteColor(3),
+                              isArchived = false,
+                              position = 0,
+                              unit = "",
+                              target = 0.0,
+                              type = HabitType.BOOLEAN_HABIT)
 
-    lateinit var repository: HabitRepository
-    lateinit private var original0: Habit
-    lateinit private var original1: Habit
-    lateinit private var original2: Habit
+        val original1 = Habit(id = 1,
+                              name = "Exercise",
+                              description = "Did you exercise for at least 20 minutes?",
+                              frequency = Frequency(1, 2),
+                              color = PaletteColor(4),
+                              isArchived = false,
+                              position = 1,
+                              unit = "",
+                              target = 0.0,
+                              type = HabitType.BOOLEAN_HABIT)
 
-    @BeforeTest
-    fun setUp() {
-        original0 = Habit(id = 0,
-                          name = "Wake up early",
-                          description = "Did you wake up before 6am?",
-                          frequency = Frequency(1, 1),
-                          color = PaletteColor(3),
-                          isArchived = false,
-                          position = 0,
-                          unit = "",
-                          target = 0.0,
-                          type = HabitType.BOOLEAN_HABIT)
+        val original2 = Habit(id = 2,
+                              name = "Learn Japanese",
+                              description = "Did you study Japanese today?",
+                              frequency = Frequency(1, 1),
+                              color = PaletteColor(3),
+                              isArchived = false,
+                              position = 2,
+                              unit = "",
+                              target = 0.0,
+                              type = HabitType.BOOLEAN_HABIT)
 
-        original1 = Habit(id = 1,
-                          name = "Exercise",
-                          description = "Did you exercise for at least 20 minutes?",
-                          frequency = Frequency(1, 2),
-                          color = PaletteColor(4),
-                          isArchived = false,
-                          position = 1,
-                          unit = "",
-                          target = 0.0,
-                          type = HabitType.BOOLEAN_HABIT)
+        val repository = HabitRepository(db)
 
-        original2 = Habit(id = 2,
-                          name = "Learn Japanese",
-                          description = "Did you study Japanese today?",
-                          frequency = Frequency(1, 1),
-                          color = PaletteColor(3),
-                          isArchived = false,
-                          position = 2,
-                          unit = "",
-                          target = 0.0,
-                          type = HabitType.BOOLEAN_HABIT)
-
-        repository = HabitRepository(db)
-    }
-
-    @Test
-    fun testFindAll() {
         var habits = repository.findAll()
         assertEquals(0, repository.nextId())
         assertEquals(0, habits.size)
diff --git a/core/src/commonTest/kotlin/org/isoron/uhabits/models/PreferencesRepositoryTest.kt b/core/src/commonTest/kotlin/org/isoron/uhabits/models/PreferencesRepositoryTest.kt
index 9f7b673ee..4a3f70839 100644
--- a/core/src/commonTest/kotlin/org/isoron/uhabits/models/PreferencesRepositoryTest.kt
+++ b/core/src/commonTest/kotlin/org/isoron/uhabits/models/PreferencesRepositoryTest.kt
@@ -23,8 +23,8 @@ import org.isoron.*
 import kotlin.test.*
 
 class PreferencesRepositoryTest : BaseTest() {
-    @Test
-    fun testUsage() {
+    suspend fun testUsage() {
+        val db = resolver.getDatabase()
         val prefs = PreferencesRepository(db)
 
         assertEquals("default", prefs.getString("non_existing_key", "default"))
diff --git a/core/src/jsMain/kotlin/org/isoron/platform/io/JsDatabase.kt b/core/src/jsMain/kotlin/org/isoron/platform/io/JsDatabase.kt
index 850b0e0d9..89655e825 100644
--- a/core/src/jsMain/kotlin/org/isoron/platform/io/JsDatabase.kt
+++ b/core/src/jsMain/kotlin/org/isoron/platform/io/JsDatabase.kt
@@ -29,6 +29,7 @@ class JsPreparedStatement(val stmt: dynamic) : PreparedStatement {
     }
 
     override fun finalize() {
+        stmt.free()
     }
 
     override fun getInt(index: Int): Int {
diff --git a/core/src/jsMain/kotlin/org/isoron/platform/io/JsFiles.kt b/core/src/jsMain/kotlin/org/isoron/platform/io/JsFiles.kt
index 98345e3c3..0b876d267 100644
--- a/core/src/jsMain/kotlin/org/isoron/platform/io/JsFiles.kt
+++ b/core/src/jsMain/kotlin/org/isoron/platform/io/JsFiles.kt
@@ -19,8 +19,10 @@
 
 package org.isoron.platform.io
 
+import kotlinx.coroutines.*
 import org.w3c.dom.events.*
 import org.w3c.xhr.*
+import kotlin.js.*
 
 class JsFileOpener : FileOpener {
     override fun openUserFile(filename: String): UserFile {
@@ -34,21 +36,26 @@ class JsFileOpener : FileOpener {
 
 class JsUserFile(filename: String) : UserFile {
     override fun delete() {
+        TODO()
     }
 
     override fun exists(): Boolean {
-        return false
+        TODO()
     }
 }
 
 class JsResourceFile(val filename: String) : ResourceFile {
-    override fun readLines(): List<String> {
-        val xhr = XMLHttpRequest()
-        xhr.open("GET", "/assets/$filename", false)
-        xhr.send()
-        return xhr.responseText.lines()
+    override suspend fun lines(): List<String> {
+        return Promise<List<String>> { resolve, reject ->
+            val xhr = XMLHttpRequest()
+            xhr.open("GET", "/assets/$filename", true)
+            xhr.onload = { resolve(xhr.responseText.lines()) }
+            xhr.onerror = { reject(Exception()) }
+            xhr.send()
+        }.await()
     }
 
     override fun copyTo(dest: UserFile) {
+        TODO()
     }
 }
diff --git a/core/src/jsTest/kotlin/org/isoron/DependencyResolver.kt b/core/src/jsTest/kotlin/org/isoron/DependencyResolver.kt
index 56263c502..c3d456a3c 100644
--- a/core/src/jsTest/kotlin/org/isoron/DependencyResolver.kt
+++ b/core/src/jsTest/kotlin/org/isoron/DependencyResolver.kt
@@ -21,15 +21,18 @@ package org.isoron
 
 import org.isoron.platform.gui.*
 import org.isoron.platform.io.*
+import org.isoron.uhabits.*
 import org.w3c.dom.*
 import kotlin.browser.*
 
 actual class DependencyResolver {
     actual fun getFileOpener(): FileOpener = JsFileOpener()
 
-    actual fun getDatabase(): Database {
-        val db = eval("new SQL.Database()")
-        return JsDatabase(db)
+    actual suspend fun getDatabase(): Database {
+        val nativeDB = eval("new SQL.Database()")
+        val db = JsDatabase(nativeDB)
+        db.migrateTo(LOOP_DATABASE_VERSION, getFileOpener(), StandardLog())
+        return db
     }
 
     actual fun createCanvas(width: Int, height: Int): Canvas {
diff --git a/core/src/jsTest/kotlin/org/isoron/JsAsyncTests.kt b/core/src/jsTest/kotlin/org/isoron/JsAsyncTests.kt
new file mode 100644
index 000000000..f026c66ed
--- /dev/null
+++ b/core/src/jsTest/kotlin/org/isoron/JsAsyncTests.kt
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2016-2019 Álinson Santos Xavier <isoron@gmail.com>
+ *
+ * This file is part of Loop Habit Tracker.
+ *
+ * Loop Habit Tracker 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.
+ *
+ * Loop Habit Tracker 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 org.isoron
+
+import kotlinx.coroutines.*
+import org.isoron.platform.io.*
+import org.isoron.uhabits.models.*
+import kotlin.test.*
+
+class JsAsyncTests {
+    @Test
+    fun testLines() = GlobalScope.promise { FilesTest().testLines() }
+
+    @Test
+    fun testDatabase() = GlobalScope.promise { DatabaseTest().testUsage() }
+
+    @Test
+    fun testCheckmarkRepository() = GlobalScope.promise { CheckmarkRepositoryTest().testCRUD() }
+
+    @Test
+    fun testHabitRepository() = GlobalScope.promise { HabitRepositoryTest().testCRUD() }
+
+    @Test
+    fun testPreferencesRepository() = GlobalScope.promise { PreferencesRepositoryTest().testUsage() }
+}
\ No newline at end of file
diff --git a/core/src/jvmMain/kotlin/org/isoron/platform/io/JavaFiles.kt b/core/src/jvmMain/kotlin/org/isoron/platform/io/JavaFiles.kt
index b87565a03..7b57feace 100644
--- a/core/src/jvmMain/kotlin/org/isoron/platform/io/JavaFiles.kt
+++ b/core/src/jvmMain/kotlin/org/isoron/platform/io/JavaFiles.kt
@@ -23,12 +23,12 @@ import java.io.*
 import java.nio.file.*
 
 class JavaResourceFile(private val path: Path) : ResourceFile {
-    override fun copyTo(dest: UserFile) {
-        Files.copy(path, (dest as JavaUserFile).path)
+    override suspend fun lines(): List<String> {
+        return Files.readAllLines(path)
     }
 
-    override fun readLines(): List<String> {
-        return Files.readAllLines(path)
+    override fun copyTo(dest: UserFile) {
+        Files.copy(path, (dest as JavaUserFile).path)
     }
 
     fun stream(): InputStream {
diff --git a/core/src/jvmTest/kotlin/org/isoron/DependencyResolver.kt b/core/src/jvmTest/kotlin/org/isoron/DependencyResolver.kt
index 363dd0490..c8fff12f4 100644
--- a/core/src/jvmTest/kotlin/org/isoron/DependencyResolver.kt
+++ b/core/src/jvmTest/kotlin/org/isoron/DependencyResolver.kt
@@ -19,6 +19,7 @@
 
 package org.isoron
 
+import kotlinx.coroutines.*
 import org.isoron.platform.gui.*
 import org.isoron.platform.io.*
 import org.isoron.uhabits.*
@@ -34,7 +35,7 @@ actual class DependencyResolver actual constructor() {
 
     actual fun getFileOpener(): FileOpener = fileOpener
 
-    actual fun getDatabase(): Database {
+    actual suspend fun getDatabase(): Database {
         val dbFile = fileOpener.openUserFile("test.sqlite3")
         if (dbFile.exists()) dbFile.delete()
         val db = databaseOpener.open(dbFile)
diff --git a/core/src/jvmTest/kotlin/org/isoron/JavaAsyncTests.kt b/core/src/jvmTest/kotlin/org/isoron/JavaAsyncTests.kt
new file mode 100644
index 000000000..f49180335
--- /dev/null
+++ b/core/src/jvmTest/kotlin/org/isoron/JavaAsyncTests.kt
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2016-2019 Álinson Santos Xavier <isoron@gmail.com>
+ *
+ * This file is part of Loop Habit Tracker.
+ *
+ * Loop Habit Tracker 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.
+ *
+ * Loop Habit Tracker 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 org.isoron
+
+import kotlinx.coroutines.*
+import org.isoron.platform.io.*
+import org.isoron.uhabits.models.*
+import org.junit.*
+
+class JavaAsyncTests {
+    @Test
+    fun testLines() = runBlocking { FilesTest().testLines() }
+
+    @Test
+    fun testDatabase() = runBlocking { DatabaseTest().testUsage() }
+
+    @Test
+    fun testCheckmarkRepository() = runBlocking { CheckmarkRepositoryTest().testCRUD() }
+
+    @Test
+    fun testHabitRepository() = runBlocking { HabitRepositoryTest().testCRUD() }
+
+    @Test
+    fun testPreferencesRepository() = runBlocking { PreferencesRepositoryTest().testUsage() }
+}
\ No newline at end of file
diff --git a/web/package-lock.json b/web/package-lock.json
index 40498b3c8..e14133a85 100644
--- a/web/package-lock.json
+++ b/web/package-lock.json
@@ -3615,6 +3615,11 @@
         "kotlin": "1.3.21"
       }
     },
+    "kotlinx-coroutines-core": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/kotlinx-coroutines-core/-/kotlinx-coroutines-core-1.1.1.tgz",
+      "integrity": "sha512-RnxF8HVQlMmLQcmJXSZQowR9WpsoeslY6ogqDovb/2HumkkaUBlJuR4eiXwX0DDnoAq8mGPvncl1lRAhK2+ovg=="
+    },
     "lcid": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/lcid/-/lcid-2.0.0.tgz",
diff --git a/web/package.json b/web/package.json
index f0734849f..05f48df4d 100644
--- a/web/package.json
+++ b/web/package.json
@@ -20,6 +20,7 @@
     "babel-preset-react": "^6.24.1",
     "kotlin": "^1.3.21",
     "kotlin-test": "^1.3.21",
+    "kotlinx-coroutines-core": "^1.1.1",
     "sql.js": "^0.5.0"
   },
   "devDependencies": {