How do I write an async test method in F#?
I'm referencing the following code:
[TestMethod]
public async Task CorrectlyFailingTest()
{
await SystemUnderTest.FailAsync();
}
This is my failed attempt:
[<Test>]
let ``Correctly failing test``() = async {
SystemUnderTest.FailAsync() | Async.RunSynchronously
}
So after a bit of research, it turns out that this is more difficult than it ought to be. https://github.com/nunit/nunit/issues/34
That being said a workaround was mentioned. This seems kinda lame but, it looks like declaring a task delegate outside as a member and leveraging it is a viable work around.
The examples mentioned in the thread:
open System.Threading.Tasks
open System.Runtime.CompilerServices
let toTask computation : Task = Async.StartAsTask computation :> _
[<Test>]
[<AsyncStateMachine(typeof<Task>)>]
member x.``Test``() = toTask <| async {
do! asyncStuff()
}
And
open System.Threading.Tasks
open NUnit.Framework
let toAsyncTestDelegate computation =
new AsyncTestDelegate(fun () -> Async.StartAsTask computation :> Task)
[<Test>]
member x.``TestWithNUnit``() =
Assert.ThrowsAsync<InvalidOperationException>(asyncStuff 123 |> toAsyncTestDelegate)
|> ignore
[<Test>]
member x.``TestWithFsUnit``() =
asyncStuff 123
|> toAsyncTestDelegate
|> should throw typeof<InvalidOperationException>
XUnit had a similar problem and did come up with a solution:
https://github.com/xunit/xunit/issues/955
So you should be able to do this in xunit
[<Fact>]
let ``my async test``() =
async {
let! x = someAsyncCall()
AssertOnX
}
Sorry if this is not the most satisfying answer.
open Xunit
[<Fact>]
let ``my async test``() =
async {
do! Async.AwaitTask(someAsyncCall())|> Async.Ignore
AssertOnX
}
I asked https://github.com/fsprojects/FsUnit/issues/153 because I think that it is a responsibility of the F# unit testing framework to provide a right binding.
Meanwhile, this looks the best for me.
open System.Threading.Tasks
let runAsyncTest async = async |> Async.StartImmediateAsTask :> Task
[<Test>]
let ``Some test`` () = runAsyncTest <| async {
}
This is an old question but now can use the task builder from the Ply package for testing C# async methods in Xunit like so:
open FSharp.Control.Tasks
open System.Threading
open Xunit
let ``Test some Task returning async method`` () =
task {
let! actual = MyType.GetSomethingAsync()
Assert.Equal(expected, actual)
return ()
}
Related
I'm new in Unit Testing, I can't understand how to test this kind of method with kotlin, using MockK:
override fun register(firebaseId: String, uniqueId: String): Completable {
return Observable.just(0).observeOn(schedulerProvider.io()).flatMap {
val requestRegisterPushes = registerBuilder.build(firebaseId, uniqueId)
apiServiceFactory.build()
.registerPushes(requestRegisterPushes)
.subscribeOn(schedulerProvider.io())
.observeOn(schedulerProvider.ui())
}.flatMapCompletable {
Completable.complete()
}
}
This is my code for the test, the test was a success but the condition coverage does not increase.
#Test
fun `register_Test()`() {
val requestRegisterPushes = mockk<RequestRegisterPushes>(relaxed = true)
every { registerBuilder.build(any(), any(), any(), any()) } returns requestRegisterPushes
every { apiServiceFactory.build().register(requestRegisterPushes) } returns Observable.just(SimpleResponse())
val resp = userRepository.register("x7gbyb68837g78s", "XXX-XXX-XXX")
}
I would really appreciate it if you could help me a little.
Of course you don't have any coverage because code inside flatmap and flatMapCompletable operator was not executed.
You need to subscribe to Observable to make it emmit elements in you case it will emmit 0 only when you subscribe for it. That's how RxJava works. Something like this:
val subscriber = TestSubscriber<>();
val resp = userRepository.register("x7gbyb68837g78s", "XXX-XXX-XXX").subscribe(subscriber)
subscriber.assertComplete()
I have a test here, where I am attempting to validate what is being sent to a ConflatedBroadcastChannel (experimental API, I know):
#Test
fun myTest() = runBlockingTest {
val results = ArrayList<String>()
val myChannel = ConflatedBroadcastChannel<String>()
myChannel.openSubscription().consumeEach {
results.add(it)
}
myChannel.send("hello")
assertEquals(1, results.size)
}
But when I run that code, I receive an IllegalStateException with the messge: "This job has not completed yet". Anyone know what's missing? I've tried using TestCoroutineDispatcher as well to no avail.
If you just want to obtain a single value from a channel you can always use receive.
Since ConflatedBroadcastChannel caches the latest value, you can just use it like this:
#Test
fun myTest() = runBlockingTest {
val myChannel = ConflatedBroadcastChannel<String>()
myChannel.send("hello")
val subscription = myChannel.openSubscription()
val result = subscription.receive()
subscription.cancel()
assertEquals("hello", result)
}
So I thought about the message I was getting, and suspected maybe that the "job that's not completed yet" was the .consumeEach operation I was performing. So to be explicit, I wrapped the operation in a launch(myTestCoroutineDispatcher) and called cancel. This doesn't seem like the ideal way to test things, but it makes sense given that the test environment isn't really guessing when your channel should stop receiving things. Anyways, lo and behold, this works:
#Test
fun myTest() = runBlockingTest {
val results = ArrayList<String>()
val myChannel = ConflatedBroadcastChannel<String>()
launch(testMainDispatcher) {
myChannel.openSubscription().consumeEach {
results.add(it)
cancel()
}
}
myChannel.send("hello")
assertEquals(1, results.size)
}
EDIT: another thing you can do to achieve same results is val myJob = launch {...} and then at the end of your test execution, call myJob.cancel() for the same effect.
I'm trying to test that Permission.REVEAL_NOW returns the method isFeatureRevealNowAvailable.
Heres some code I already tried but didn't succeed with. Any help would be hugely appreciated as always!
Function to test:
class PermissionRepository(private val permissionApi: PermissionApi,
private val appPreferences: AppPreferences) {
fun checkPermission(permission: PermissionType, onPermissionResponse: (Boolean) -> Unit) {
Log.i("Permission", "Checking permission")
when (permission) {
PermissionType.REVEAL_NOW -> {
isFeatureRevealNowAvailable(onPermissionResponse, ::errorHandler)
}
}
}
Attempted solution:
#RunWith(MockitoJUnitRunner::class)
class PermissionRepositoryTest{
#Test
fun checkPermissionTest() {
val mockPermissionRepository = mock(PermissionRepository::class.java)
val mockPermissionApi = mock(PermissionApi::class.java)
val result = mockPermissionRepository.checkPermission(PermissionType.REVEAL_NOW, onPermissionResponse = null)
//Unsure of what to use here AssertThat or Mockito's "when" function
}
}
private fun isFeatureRevealNowAvailable(permissionResponseHandler: (Boolean) -> Unit, permissionError: (Throwable) -> Unit) {
permissionApi.getRevealNowPermission().enqueue(object : Callback<PermissionResponse> {
override fun onFailure(call: Call<PermissionResponse>, t: Throwable) {
permissionResponseHandler(false)
permissionError(t)
}
override fun onResponse(call: Call<PermissionResponse>, response: Response<PermissionResponse>) {
val permissionResult = response.body()?.isRevealNow ?: false
updateUserLocalPermission(PermissionType.REVEAL_NOW, permissionResult)
permissionResponseHandler(permissionResult)
}
})
}
(TL;DR - go to Example)
Since you don't define specifically what you want to test or achieve, I will give some overall tips:
Mocking
Never mock the class you want to test
val mockPermissionRepository = mock(PermissionRepository::class.java)
Mock only what you want to exclude from your test but rely on
Try to avoid mocks whenever it is possible and makes sence, because they simulate a perfect world, not the real behaviour
Test naming
Use proper names to describe what you want to achive with your test. My personal favourite is to start the sentence with the word "should ..."
Example
Two tests I could image to write for your function:
#Test
fun `should invoke reveal permission on PermissionApi when type is REVEAL_NOW`(){
val mockPermissionApi = mock(PermissionApi::class.java)
val permissionRepository = PermissionRepository(mockPermissionApi, mock())
permissionRepository.checkPermission(PermissionType.REVEAL_NOW, onPermissionResponse = {})
verify(mockPermissionApi, times(1)).getRevealNowPermission()
}
#Test
fun `should do nothing when type is not REVEAL_NOW`() {
val mockPermissionApi = mock(PermissionApi::class.java)
val permissionRepository = PermissionRepository(mockPermissionApi, mock())
permissionRepository.checkPermission(PermissionType.ELSE, onPermissionResponse = {})
verify(mockPermissionApi, times(0)).getRevealNowPermission()
}
Software versions:
Akka 2.4.4
Slick 3.1.0
I want to process elements from an Akka stream in a Slick transaction.
Here is some simplified code to illustrate one possible approach:
def insert(d: AnimalFields): DBIO[Long] =
animals returning animals.map(_.id) += d
val source: Source[AnimalFields, _]
val sourceAsTraversable = ???
db.run((for {
ids <- DBIO.sequence(sourceAsTraversable.map(insert))
} yield { ids }).transactionally)
One solution I could come up with so far is blocking each future to traverse the elements:
class TraversableQueue[T](sinkQueue: SinkQueue[T]) extends Traversable[T] {
#tailrec private def next[U](f: T => U): Unit = {
val nextElem = Await.result(sinkQueue.pull(), Duration.Inf)
if (nextElem.isDefined) {
f(nextElem.get)
next(f)
}
}
def foreach[U](f: T => U): Unit = next(f)
}
val sinkQueue = source.runWith(Sink.queue())
val queue = new TraversableQueue(sinkQueue)
Now I can pass the traversable queue to DBIO.sequence(). This defeats the purpose of streamed processing, though.
Another approach I found is this:
def toDbioAction[T](queue: SinkQueue[DBIOAction[S, NoStream, Effect.All]]):
DBIOAction[Queue[T], NoStream, Effect.All] =
DBIO.from(queue.pull() map { tOption =>
tOption match {
case Some(action) =>
action.flatMap(t => toDbioAction(queue).map(_ :+ t))
case None => DBIO.successful(Queue())
}
}).flatMap(r => r)
With this method, a sequence of DBIOActions can be generated without blocking:
toDbioAction(source.runWith(Sink.queue()))
Is there any better / more idiomatic way to achieve the desired result?
Here is my implementation of sourceAsTraversable:
import scala.collection.JavaConverters._
def sourceAsTraversable[A](source: Source[A, _])(implicit mat: Materializer): Traversable[A] =
source.runWith(StreamConverters.asJavaStream()).iterator().asScala.toIterable
The issue with TraversableQueue was that the forEach had to finish processing the stream fully - it did not support the "break" concept, so methods like "drop"/"take", etc. would still have to process whole source. This could be important from error handling point of view and failing fast.
I am building a library that interrogates its running environment to return values to the asking program. Sometimes as simple as
pub fn func_name() -> Option<String> {
match env::var("ENVIRONMENT_VARIABLE") {
Ok(s) => Some(s),
Err(e) => None
}
}
but sometimes a good bit more complicated, or even having a result composed of various environment variables. How can I test that these methods are functioning as expected?
"How do I test X" is almost always answered with "by controlling X". In this case, you need to control the environment variables:
use std::env;
fn env_is_set() -> bool {
match env::var("ENVIRONMENT_VARIABLE") {
Ok(s) => s == "yes",
_ => false
}
}
#[test]
fn when_set_yes() {
env::set_var("ENVIRONMENT_VARIABLE", "yes");
assert!(env_is_set());
}
#[test]
fn when_set_no() {
env::set_var("ENVIRONMENT_VARIABLE", "no");
assert!(!env_is_set());
}
#[test]
fn when_unset() {
env::remove_var("ENVIRONMENT_VARIABLE");
assert!(!env_is_set());
}
However, you need to be aware that environment variables are a shared resource. From the docs for set_var, emphasis mine:
Sets the environment variable k to the value v for the currently running process.
You may also need to be aware that the Rust test runner runs tests in parallel by default, so it's possible to have one test clobber another.
Additionally, you may wish to "reset" your environment variables to a known good state after the test.
Your other option (if you don't want to mess around with actually setting environment variables) is to abstract the call away. I am only just learning Rust and so I am not sure if this is "the Rust way(tm)" to do it... but this is certainly how I would do it in another language/environment:
use std::env;
pub trait QueryEnvironment {
fn get_var(&self, var: &str) -> Result<String, std::env::VarError>;
}
struct MockQuery;
struct ActualQuery;
impl QueryEnvironment for MockQuery {
fn get_var(&self, _var: &str) -> Result<String, std::env::VarError> {
Ok("Some Mocked Result".to_string()) // Returns a mocked response
}
}
impl QueryEnvironment for ActualQuery {
fn get_var(&self, var: &str) -> Result<String, std::env::VarError> {
env::var(var) // Returns an actual response
}
}
fn main() {
env::set_var("ENVIRONMENT_VARIABLE", "user"); // Just to make program execute for ActualQuery type
let mocked_query = MockQuery;
let actual_query = ActualQuery;
println!("The mocked environment value is: {}", func_name(mocked_query).unwrap());
println!("The actual environment value is: {}", func_name(actual_query).unwrap());
}
pub fn func_name<T: QueryEnvironment>(query: T) -> Option<String> {
match query.get_var("ENVIRONMENT_VARIABLE") {
Ok(s) => Some(s),
Err(_) => None
}
}
Example on the rust playground
Notice how the actual call panics. This is the implementation you would use in actual code. For your tests, you would use the mocked ones.
EDIT:
The test helpers below are now available in a dedicated crate
Disclaimer: I'm a co-author
I had the same need and implemented some small test helpers which take care of the caveats mentioned by #Shepmaster .
These test helpers enable testing like so:
#[test]
fn test_default_log_level_is_info() {
with_env_vars(
vec![
("LOGLEVEL", None),
("SOME_OTHER_VAR", Some("foo"))
],
|| {
let actual = Config::new();
assert_eq!("INFO", actual.log_level);
},
);
}
with_env_vars will take care of:
Avoiding side effects when running tests in parallel
Resetting the env variables to their original values when the test closure completes
Support for unsetting environment variables during the test closure
All of the above, also when the test-closure panics.
The helper:
use lazy_static::lazy_static;
use std::env::VarError;
use std::panic::{RefUnwindSafe, UnwindSafe};
use std::sync::Mutex;
use std::{env, panic};
lazy_static! {
static ref SERIAL_TEST: Mutex<()> = Default::default();
}
/// Sets environment variables to the given value for the duration of the closure.
/// Restores the previous values when the closure completes or panics, before unwinding the panic.
pub fn with_env_vars<F>(kvs: Vec<(&str, Option<&str>)>, closure: F)
where
F: Fn() + UnwindSafe + RefUnwindSafe,
{
let guard = SERIAL_TEST.lock().unwrap();
let mut old_kvs: Vec<(&str, Result<String, VarError>)> = Vec::new();
for (k, v) in kvs {
let old_v = env::var(k);
old_kvs.push((k, old_v));
match v {
None => env::remove_var(k),
Some(v) => env::set_var(k, v),
}
}
match panic::catch_unwind(|| {
closure();
}) {
Ok(_) => {
for (k, v) in old_kvs {
reset_env(k, v);
}
}
Err(err) => {
for (k, v) in old_kvs {
reset_env(k, v);
}
drop(guard);
panic::resume_unwind(err);
}
};
}
fn reset_env(k: &str, old: Result<String, VarError>) {
if let Ok(v) = old {
env::set_var(k, v);
} else {
env::remove_var(k);
}
}
A third option, and one I think is better, is to pass in the existing type - rather than creating a new abstraction that everyone would have to coerce to.
pub fn new<I>(vars: I)
where I: Iterator<Item = (String, String)>
{
for (x, y) in vars {
println!("{}: {}", x, y)
}
}
#[test]
fn trivial_call() {
let vars = [("fred".to_string(), "jones".to_string())];
new(vars.iter().cloned());
}
Thanks to qrlpz on #rust for helping me get this sorted for my program, just sharing the result to help others :)