fix: make dex optional on the clearinghouseState subscription

lib/hyperliquid/api/subscription/clearinghouse_state.ex

@@ -40,15 +40,15 @@ defmodule Hyperliquid.Api.Subscription.ClearinghouseState do
     changeset =
       {%{}, types}
       |> cast(params, Map.keys(types))
-      |> validate_required([:user, :dex])
+      |> validate_required([:user])
       |> validate_format(:user, ~r/^0x[0-9a-fA-F]{40}$/)
 
     if changeset.valid? do
       {:ok,
        %{
          type: "clearinghouseState",
          user: get_change(changeset, :user),
-         dex: get_change(changeset, :dex)
+         dex: get_change(changeset, :dex) || ""
        }}
     else
       {:error, changeset}

test/api/subscription/clearinghouse_state_test.exs

@@ -0,0 +1,31 @@
+defmodule Hyperliquid.Api.Subscription.ClearinghouseStateTest do
+  use ExUnit.Case, async: true
+
+  alias Hyperliquid.Api.Subscription.ClearinghouseState
+
+  test "builds a request for the main perps market when dex is omitted" do
+    assert {:ok, %{type: "clearinghouseState", user: "0x" <> _, dex: ""}} =
+             ClearinghouseState.build_request(%{user: "0x1234567890123456789012345678901234567890"})
+  end
+
+  test "builds a request for the main perps market when dex is the empty string" do
+    assert {:ok, %{dex: ""}} =
+             ClearinghouseState.build_request(%{
+               user: "0x1234567890123456789012345678901234567890",
+               dex: ""
+             })
+  end
+
+  test "builds a request for a named builder-deployed dex" do
+    assert {:ok, %{dex: "test"}} =
+             ClearinghouseState.build_request(%{
+               user: "0x1234567890123456789012345678901234567890",
+               dex: "test"
+             })
+  end
+
+  test "still requires a user" do
+    assert {:error, changeset} = ClearinghouseState.build_request(%{dex: ""})
+    assert {"can't be blank", [validation: :required]} = changeset.errors[:user]
+  end
+end