Add Runtime.Bus with channel-based effect interpreter

test/BusSpec.hs

@@ -0,0 +1,43 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module BusSpec (spec) where
+
+import Control.Concurrent.STM
+  ( atomically
+  , dupTChan
+  , readTChan
+  , writeTChan
+  )
+import Data.Aeson (Value (..))
+import HomeAssistant.Controller (HASSEff (..), Service (..))
+import HomeAssistant.Runtime.Bus
+import Test.Hspec
+
+spec :: Spec
+spec = describe "Bus" $ do
+  it "broadcasts inbound messages to every dup'd channel in order" $ do
+    bus <- newBus 0
+    p1 <- atomically $ dupTChan (busInbound bus)
+    p2 <- atomically $ dupTChan (busInbound bus)
+    atomically $ writeTChan (busInbound bus) (Number 1)
+    atomically $ writeTChan (busInbound bus) (Number 2)
+    r1 <- atomically $ (,) <$> readTChan p1 <*> readTChan p1
+    r2 <- atomically $ (,) <$> readTChan p2 <*> readTChan p2
+    r1 `shouldBe` (Number 1, Number 2)
+    r2 `shouldBe` (Number 1, Number 2)
+
+  it "channelHassEval writes CallService to the outbound channel" $ do
+    bus <- newBus 0
+    let svc = Service "light" "turn_on" Nothing "light.bedroom_masse"
+    channelHassEval bus (CallService svc)
+    atomically (readTChan (busOutbound bus)) `shouldReturn` svc
+
+  it "channelHassEval leaves Pure untouched" $ do
+    bus <- newBus 0
+    channelHassEval bus (Pure 42) `shouldReturn` (42 :: Int)
+
+  it "generates unique sequential call ids" $ do
+    gen <- mkCallIdGen 0
+    a <- generateCallId gen
+    b <- generateCallId gen
+    (a, b) `shouldBe` (1, 2)

test/Main.hs

@@ -1,4 +1,7 @@
 module Main (main) where
 
+import Test.Hspec (hspec)
+import qualified BusSpec
+
 main :: IO ()
-main = putStrLn "Test suite not yet implemented."
+main = hspec BusSpec.spec