lib/tests: Add type deprecation tests

lib/tests/modules/type-deprecation.nix

@@ -0,0 +1,39 @@
+{ lib, ... }: {
+
+  options.simple = lib.mkOption {
+    type = lib.mkOptionType {
+      name = "simple";
+      deprecationMessage = "simple shall not be used";
+    };
+    default = throw "";
+  };
+
+  options.infinite = lib.mkOption {
+    type =
+      let
+        t = lib.mkOptionType {
+          name = "infinite";
+          deprecationMessage = "infinite shall not be used";
+        };
+        r = lib.types.either t (lib.types.attrsOf r);
+      in r;
+    default = throw "";
+  };
+
+  options.nested = lib.mkOption {
+    type =
+      let
+        left = lib.mkOptionType {
+          name = "left";
+          deprecationMessage = "left shall not be used";
+        };
+        right = lib.mkOptionType {
+          name = "right";
+          deprecationMessage = "right shall not be used";
+        };
+      in lib.types.either left right;
+
+    default = throw "";
+  };
+
+}