Merge pull request #15 from turion/dev_more_properties

more test properties

lib/hallux/seq.ex

@@ -219,7 +219,7 @@ defmodule Hallux.Seq do
       iex> rest
       #HalluxSeq<[1, 2, 3, 4, 5, 6, 7, 8, 9]>
   """
-  @spec view_r(t(val)) :: nil | {val, t(val)} when val: value
+  @spec view_r(t(val)) :: nil | {t(val), val} when val: value
   def view_r(%__MODULE__{t: t}) do
     with {rest, %Elem{e: x}} <- FingerTree.view_r(t) do
       {%__MODULE__{t: rest}, x}

test/hallux/seq_test.exs

@@ -40,6 +40,37 @@ defmodule Hallux.SeqTest do
         assert Valid.valid?(seq)
       end
     end
+
+    property "cons . view_l = id" do
+      check all(
+              s <- seq(),
+              item <- term()
+            ) do
+        {item_, s_} = Seq.view_l(Seq.cons(s, item))
+        assert_equal(s, s_)
+        assert item == item_
+      end
+    end
+  end
+
+  property "snoc . view_r = id" do
+    check all(
+            s <- seq(),
+            item <- term()
+          ) do
+      {s_, item_} = Seq.view_r(Seq.snoc(s, item))
+      assert_equal(s, s_)
+      assert item == item_
+    end
+  end
+
+  property "concat . to_list = to_list . ++" do
+    check all(
+      s1 <- seq(),
+      s2 <- seq()
+    ) do
+      assert Enum.to_list(Seq.concat(s1, s2)) == Enum.to_list(s1) ++ Enum.to_list(s2)
+    end
   end
 
   defp assert_equal(s1 = %Seq{}, s2 = %Seq{}) do