Merge pull request #80 from epochtalk/validate-mutually-exclusive-fixes

Validate mutually exclusive fixes

Author: akinsey

lib/epochtalk_server_web/helpers/validate.ex

@@ -8,27 +8,10 @@ defmodule EpochtalkServerWeb.Helpers.Validate do
 
   @doc """
   Ensure that `keys` provided in list are mutually exclusive within `attrs` map.
-
-  ## Example
-    iex> alias EpochtalkServerWeb.Helpers.Validate
-    iex> attrs = %{"page" => 1}
-    iex> Validate.mutually_exclusive!(attrs, ["page", "start"])
-    :ok
-    iex> attrs = %{"start" => 1}
-    iex> Validate.mutually_exclusive!(attrs, ["page", "start"])
-    :ok
-    iex> Validate.mutually_exclusive!(attrs, ["start"])
-    :ok
-    iex> attrs = %{"page" => 1, "start" => 1}
-    iex> Validate.mutually_exclusive!(attrs, ["page", "start"])
-    ** (EpochtalkServerWeb.CustomErrors.InvalidPayload) The following payload parameters cannot be passed at the same time: page, start
   """
   @spec mutually_exclusive!(attrs :: map, keys :: [String.t()]) :: :ok | no_return
   def mutually_exclusive!(attrs, keys) when is_map(attrs) and is_list(keys) do
-    contains_all_keys =
-      Enum.reduce(keys, true, fn key, acc -> acc && Map.has_key?(attrs, key) end)
-
-    if contains_all_keys && length(keys) > 1,
+    if map_contains_any_two_keys_in_list?(attrs, keys),
       do:
         raise(InvalidPayload,
           message:
@@ -152,6 +135,29 @@ defmodule EpochtalkServerWeb.Helpers.Validate do
     end
   end
 
+  # entrypoint
+  defp map_contains_any_two_keys_in_list?(map, list),
+    do: map_contains_any_two_keys_in_list?(map, list, false)
+
+  # if map is empty, return false
+  defp map_contains_any_two_keys_in_list?(map, _list, _key_found?) when map == %{}, do: false
+  # if list is empty, return false
+  defp map_contains_any_two_keys_in_list?(_map, [], _key_found?), do: false
+  # if key_found? is false
+  defp map_contains_any_two_keys_in_list?(map, [key | keys] = _list, false = _key_found?) do
+    # check next key with updated key_found?
+    map_contains_any_two_keys_in_list?(map, keys, Map.has_key?(map, key))
+  end
+
+  # if key_found? is true
+  defp map_contains_any_two_keys_in_list?(map, [key | keys] = _list, true = key_found?) do
+    # if current key is in map, return true
+    if Map.has_key?(map, key),
+      do: true,
+      # otherwise, check next key
+      else: map_contains_any_two_keys_in_list?(map, keys, key_found?)
+  end
+
   defp to_bool(str, opts) do
     case str do
       "true" -> true

test/epochtalk_server_web/helpers/validate_test.exs

@@ -1,5 +1,56 @@
 defmodule Test.EpochtalkServerWeb.Helpers.Validate do
   use Test.Support.ConnCase, async: true
   alias EpochtalkServerWeb.Helpers.Validate
+  alias EpochtalkServerWeb.CustomErrors.InvalidPayload
   doctest Validate
+
+  describe "mutually_exclusive/2" do
+    test "given cases, returns correct result" do
+      cases = [
+        %{
+          attrs: %{"page" => 1},
+          keys: ["page", "start"],
+          result: :ok
+        },
+        %{
+          attrs: %{"start" => 1},
+          keys: ["page", "start"],
+          result: :ok
+        },
+        %{
+          attrs: %{"start" => 1},
+          keys: ["start"],
+          result: :ok
+        },
+        %{
+          attrs: %{"page" => 1, "start" => 1},
+          keys: ["page", "start"],
+          result: :error
+        },
+        %{
+          attrs: %{"page" => 1, "start" => 1, "stop" => 1},
+          keys: ["page", "start"],
+          result: :error
+        },
+        %{
+          attrs: %{"page" => 1, "stop" => 1},
+          keys: ["page", "start", "stop", "enter"],
+          result: :error
+        }
+      ]
+
+      cases
+      |> Enum.each(fn
+        %{attrs: attrs, keys: keys, result: :error} ->
+          assert_raise InvalidPayload,
+                       ~r/^The following payload parameters cannot be passed at the same time:/,
+                       fn ->
+                         Validate.mutually_exclusive!(attrs, keys)
+                       end
+
+        %{attrs: attrs, keys: keys, result: :ok} ->
+          assert Validate.mutually_exclusive!(attrs, keys) == :ok
+      end)
+    end
+  end
 end