Testing Play + Slick app - scala

Question

I've a simple CRUD app built with Scala Play 2.4.3 and Play-slick 1.1.0 (slick 3.1.0) that uses a MySQL database for persistent storage.
I was trying to create the tests for my app and I saw 2 main options:
mocking database access, that as far as I've seen, requires some code changes
make tests use an alternative database (probably, in memory H2).
What's the best approach (vantages and desavantages)?
I prefer the second approach, but I'm finding some difficulties in setting up the tests.
What do I need to do? First, I think that I need to do the tests run with a FakeApplication, right? Do I need any sbt dependency to be able to do that?
After that, how do I specify to use the H2 database?

Answer 1

I had the same struggle and I came up with a solution like this(using second approach):
Create a context for DAO to use:
trait BaseContext{
def dbName: String
val dbConfig = DatabaseConfigProvider.get[JdbcProfile](dbName)
val db = dbConfig.db
val profile = dbConfig.driver
val tables = new Tables { // this is generated by Schema Code Generator
override val profile: JdbcProfile = dbConfig.driver
}
}
#Singleton
class AppContext extends BaseContext{
def dbName = "mysql" // name in your conf right after "slick.dbs"
}
#Singleton
class TestingContext extends BaseContext{
def dbName = "h2"
}
Then create a module to bind the injection, and don't forget to enable it in conf using play.modules.enabled += "your.Module":
class ContextModule(environment: Environment, configuration: Configuration) extends AbstractModule {
override def configure(): Unit = {
if (configuration.getString("app.mode").contains("test")) {
bind(classOf[BaseContext])
.to(classOf[TestingContext])
} else {
bind(classOf[BaseContext])
.to(classOf[AppContext])
}
}
}
And inject it to every DAO you've created:
class SomeDAO #Inject()(context: BaseContext){
val dbConfig = context.dbConfig
val db = context.db
val tables = context.tables
import tables.profile.api._
def otherStuff....
// you can call db.run(...), tables.WhateverYourTableIs, tables.TableRowCaseClass, ...
}
And final step, your configuration file. In my case I used app.mode to mark the environment, and I use separate .conf for different environment. Of cause, in these conf you must have the correct DB configuration. Here's the sample:
app.mode = "test"
# Database configuration
slick.dbs = {
# for unit test
h2 {
driver = "slick.driver.H2Driver$"
db = {
url = "jdbc:h2:mem:test;MODE=MYSQL"
driver = "org.h2.Driver"
keepAliveConnection = true
}
}
}
I'm pretty sure my solution is not a elegant one, but it deliver the goods. :)
Any better solution is welcomed!

Answer 2

my solution was to add step(Play.start(fakeApp)) in the beginning of each spec, and step(Play.stop(fakeApp)) in the end of each spec.
Also:
def fakeApp: FakeApplication = {
FakeApplication(additionalConfiguration =
Map(
"slick.dbs.default.driver" -> "slick.driver.H2Driver$",
"slick.dbs.default.db.driver" -> "org.h2.Driver",
"slick.dbs.default.db.url" -> "jdbc:h2:mem:play"
))
}
This was needed because I'm using play-slick, which requires configurations like:
slick.dbs.default.driver = "slick.driver.MySQLDriver$"
slick.dbs.default.db.driver = "com.mysql.jdbc.Driver"
slick.dbs.default.db.url = "jdbc:mysql://localhost/database"
slick.dbs.default.db.user = "user"
slick.dbs.default.db.password = "password"
more info on the docs