hardcoded prng history keeps track of the history it uses

lib/decorum/prng.ex

@@ -47,29 +47,29 @@ defmodule Decorum.Prng do
   defmodule Hardcoded do
     @moduledoc false
     @type t :: %__MODULE__{
-            wholeHistory: Decorum.History.t(),
+            history: Decorum.History.t(),
             unusedHistory: Decorum.History.t()
           }
 
-    @enforce_keys [:wholeHistory, :unusedHistory]
-    defstruct [:wholeHistory, :unusedHistory]
+    @enforce_keys [:history, :unusedHistory]
+    defstruct [:history, :unusedHistory]
 
     @spec new(history :: Decorum.History.t()) :: t
     def new(history) when is_list(history) do
-      %__MODULE__{wholeHistory: history, unusedHistory: history}
+      %__MODULE__{history: [], unusedHistory: history}
     end
 
     @spec next!(prng :: t()) :: {non_neg_integer(), t()}
     def next!(%__MODULE__{unusedHistory: []} = _prng) do
       raise EmptyHistoryError, "PRNG history is empty"
     end
 
-    def next!(%__MODULE__{unusedHistory: [value | rest]} = prng) do
-      {value, %__MODULE__{prng | unusedHistory: rest}}
+    def next!(%__MODULE__{history: history, unusedHistory: [value | rest]} = prng) do
+      {value, %__MODULE__{prng | history: [value | history], unusedHistory: rest}}
     end
 
     @spec get_history(prng :: t()) :: Decorum.History.t()
-    def get_history(%__MODULE__{wholeHistory: history}), do: history
+    def get_history(%__MODULE__{history: history}), do: Enum.reverse(history)
   end
 
   @spec random() :: t()

test/prng_test.exs

@@ -21,7 +21,7 @@ defmodule PrngTest do
   end
 
   test "hardcoded Prng replays the given history" do
-    history = Enum.to_list(100..150)
+    history = Enum.to_list(101..150)
 
     {values, _prng} = get_values(Prng.hardcoded(history), 50)
 
@@ -36,9 +36,17 @@ defmodule PrngTest do
     assert_raise Decorum.Prng.EmptyHistoryError, fn -> Prng.next!(prng) end
   end
 
+  test "hardcoded Prng keeps track of the history it uses" do
+    history = Enum.to_list(50..70)
+
+    {values, prng} = get_values(Prng.hardcoded(history), 10)
+
+    assert Prng.get_history(prng) == values
+  end
+
   @spec get_values(prng :: Prng.t(), count :: non_neg_integer()) :: {non_neg_integer(), Prng.t()}
   def get_values(prng, count) do
-    0..count
+    1..count
     |> Enum.reduce({[], prng}, fn _, {list, prng} ->
       {value, new_prng} = Prng.next!(prng)
       {list ++ [value], new_prng}