diff --git a/tests/Test/Tools/Hashdict.elm b/tests/Test/Tools/Hashdict.elm
new file mode 100644
index 0000000..d389f42
--- /dev/null
+++ b/tests/Test/Tools/Hashdict.elm
@@ -0,0 +1,38 @@
+module Test.Tools.Hashdict exposing (..)
+
+import Test exposing (..)
+import Fuzz exposing (Fuzzer)
+import Internal.Tools.Hashdict as Hashdict exposing (Hashdict)
+import Test.Values.Event as TestEvent
+import Internal.Values.Event as Event
+import Json.Encode as E
+import Json.Decode as D
+import Expect
+
+fuzzer : (a -> String) -> Fuzzer a -> Fuzzer (Hashdict a)
+fuzzer toHash fuz =
+    Fuzz.map (Hashdict.fromList toHash) (Fuzz.list fuz)
+
+suite : Test
+suite =
+    describe "Hashdict"
+        [ describe "init"
+            [ test "init isEmpty"
+                ( Hashdict.empty identity
+                    |> Hashdict.isEmpty
+                    |> Expect.equal True
+                    |> always
+                )
+            ]
+        , describe "JSON"
+            [ fuzz2 (fuzzer .eventId TestEvent.fuzzer) (Fuzz.intRange 0 10) "JSON encode -> JSON decode"
+                (\hashdict indent ->
+                    hashdict
+                        |> Hashdict.encode Event.encode
+                        |> E.encode indent
+                        |> D.decodeString (Hashdict.decoder .eventId Event.decoder)
+                        |> Result.map Hashdict.toList
+                        |> Expect.equal ( Ok <| Hashdict.toList hashdict )
+                )
+            ]
+        ]