Add supervisor with backoff restarts

test/BackoffProp.hs

@@ -0,0 +1,21 @@
+module BackoffProp (spec) where
+
+import Data.Maybe (listToMaybe)
+import Data.Time (NominalDiffTime)
+import qualified Hedgehog.Gen as Gen
+import qualified Hedgehog.Range as Range
+import HomeAssistant.Runtime.Supervisor (Backoff (..), backoffDelay)
+import Test.Hspec (Spec, describe, it)
+import Test.Hspec.Hedgehog (hedgehog, forAll, (===))
+
+spec :: Spec
+spec = describe "backoffDelay" $
+  it "doubles from base, clamped at cap" $ hedgehog $ do
+    baseD <- forAll $ Gen.double (Range.constant 0.0001 10)
+    ratio <- forAll $ Gen.double (Range.constant 1 100)
+    let base = realToFrac baseD :: NominalDiffTime
+        cap = realToFrac (baseD * ratio) :: NominalDiffTime
+        backoff = Backoff base cap 1
+        delays = map (backoffDelay backoff) [1 .. 100 :: Int]
+    listToMaybe delays === Just (min cap base)
+    mapM_ (\(a, b) -> b === min cap (a * 2)) (zip delays (drop 1 delays))