How do I mock a property on a Scala companion object using Mockito and ScalaTest? - scala

Question

I have a simple companion Object that is creating a connection pool that should be globally static.
object CoreDataSource {
val pool : DataSource = getDataSource
def getDataSource: DataSource = {
...
}
}
I then use that in a variety of classes like...
class Query {
var source: DataSource = CoreDataSource.pool
def getSalutations: String = {
val conn : Connection = source.getConnection
...
}
}
Now I would like to test the getSalutations without the getDataSource actually getting called. Is there a way to mock out this call so that when the initial getDataSource call happens it hits a mock instead of the actual function?
Here is the skeleton of my test suite...
#RunWith(classOf[JUnitRunner])
class MySuite extends AnyFunSuite with MockitoSugar {
test("Test mocking the Datasource") {
// Mock object here
}
}
I Also tried...
var pool : Option[DataSource] = None
def getConnection: Connection = {
if(pool.isEmpty)
pool = getDataSource
pool.get.getConnection
}
def getDataSource: Option[DataSource] = {
...
}
}
#RunWith(classOf[JUnitRunner])
class MySuite extends AnyFunSuite with MockitoSugar with Matchers {
test("Test mocking the Datasource") {
withObjectMocked[CoreDataSource.type]{
val source = mock[DataSource]
when(CoreDataSource.getDataSource).thenReturn(Some(source))
...
assert(result == "")
}
}
}
But this throws
Mockito cannot mock/spy because :
- final class

Answer 1

I am not going to accept my workaround because it is ugly but this ended up working...
class CoreDataSource {
def getConnection = {
CoreDataSource.getConnection
}
}
object CoreDataSource {
var pool : Option[DataSource] = None
def getConnection: Connection = {
if(pool.isEmpty)
pool = getDataSource
pool.get.getConnection
}
def getDataSource: Option[DataSource] = {
...
}
}
class Query(ds: CoreDataSource = new CoreDataSource) {
def getSalutations: String = {
...
}
}
Then the following will work...
test("Single record returned") {
val cds = mock[CoreDataSource]
val source = mock[Connection]
doNothing.when(source).close()
when(cds.getConnection).thenReturn(source)
val q = new Query(cds)
val result = q.getSalutations
assert(result == "This is the test value")
}