Adds koans about tuples

lib/blank_assertions.ex

@@ -39,6 +39,10 @@ defmodule BlankAssertions do
     end
   end
 
+  def assert_raise(exception, callback) do
+    ExUnit.Assertions.assert_raise exception, fn -> callback.call() end
+  end
+
   def assert(value, opts) do
     ExUnit.Assertions.assert(value, opts)
   end

lib/koans/12_tuples.ex

@@ -0,0 +1,43 @@
+defmodule Tuples do
+  use Koans
+
+  koan "tuples have a size" do
+    assert tuple_size({:a, :b, :c}) == :__
+  end
+
+  koan "tuples can contain different things" do
+    assert {:a, 1, "hi"} == :__
+  end
+
+  koan "you can pull out individual elements" do
+    assert elem({:a, "hi"}, 1) == :__
+  end
+
+  koan "you can change individual elements of a tuple" do
+    assert put_elem({:a, "hi"}, 1, "bye") == :__
+  end
+
+  koan "you can also simply extend a tuple with new stuff" do
+    assert Tuple.insert_at({:a, "hi"}, 1, :new_thing) == :__
+  end
+
+  koan "...avoid falling of the edge" do
+    assert_raise :__, fn ->  Tuple.insert_at({:a, "hi"}, 12, :new_thing) end
+  end
+
+  koan "add things at the end" do
+    assert Tuple.append({"Huey", "Dewey"}, "Louie") == :__
+  end
+
+  koan "or also remove them" do
+    assert Tuple.delete_at({:this, :is, :not, :awesome}, 2) == :__
+  end
+
+  koan "you can't delete what you don't have" do
+    assert_raise :__, fn ->  Tuple.delete_at({:a, "hi"}, 12) end
+  end
+
+  koan "turn it into a list in case you need it" do
+    assert Tuple.to_list({:this, :can, :be, :a, :list}) == :__
+  end
+end

test/koans_harness_test.exs

@@ -217,6 +217,23 @@ defmodule KoansHarnessTest do
     test_all(Tasks, answers)
   end
 
+  test "Tuples" do
+    answers = [
+      3,
+      {:a, 1, "hi"},
+      "hi",
+      {:a, "bye"},
+      {:a, :new_thing, "hi"},
+      ArgumentError,
+      {"Huey", "Dewey", "Louie"},
+      {:this, :is, :awesome},
+      ArgumentError,
+      [:this, :can, :be, :a, :list]
+    ]
+
+    test_all(Tuples, answers)
+  end
+
   def test_all(module, answers) do
     module.all_koans
     |> Enum.zip(answers)