From a096774fa82598dcc67d31f78b43ef4475b9f8c9 Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Sun, 8 Dec 2019 14:57:25 -0500
Subject: [PATCH] Add intcode VM tests

---
 lib/day5/day5.ex         |   8 +--
 test/intcode/vm_test.exs | 120 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 124 insertions(+), 4 deletions(-)
 create mode 100644 test/intcode/vm_test.exs

diff --git a/lib/day5/day5.ex b/lib/day5/day5.ex
index 62d4b16..4433f57 100644
--- a/lib/day5/day5.ex
+++ b/lib/day5/day5.ex
@@ -98,8 +98,8 @@ defmodule Day5 do
     # IO.inspect(memory)
 
     case eval(Enum.drop(memory, ip), memory, parent) do
-      {_memory, :halt} ->
-        send(parent, {:halt, self()})
+      {memory, :halt} ->
+        send(parent, {:halt, self(), memory})
 
       {memory, :cont, offset} ->
         run(memory, parent, ip + offset)
@@ -109,8 +109,8 @@ defmodule Day5 do
     end
   end
 
-  def run(_memory, parent, _) do
-    send(parent, {:ok, self()})
+  def run(memory, parent, _) do
+    send(parent, {:ok, self(), memory})
   end
 
   defmacro opcode(op, expected) do
diff --git a/test/intcode/vm_test.exs b/test/intcode/vm_test.exs
new file mode 100644
index 0000000..e132b5e
--- /dev/null
+++ b/test/intcode/vm_test.exs
@@ -0,0 +1,120 @@
+defmodule VMTest do
+  use ExUnit.Case
+  doctest Day5
+
+  def run(prog, io \\ []) do
+    parent = self()
+
+    pid =
+      spawn(fn ->
+        Day5.run(prog, parent)
+      end)
+
+    handle_io(pid, io)
+
+    receive do
+      {:halt, ^pid, memory} ->
+        {:halt, memory}
+
+      {:ok, ^pid, memory} ->
+        {:ok, memory}
+
+      msg ->
+        IO.inspect(msg)
+    end
+  end
+
+  def handle_io(_, []), do: :ok
+
+  def handle_io(pid, [head | rest]) do
+    case head do
+      {:in, input} ->
+        receive do
+          {:in, ^pid} -> send(pid, {:in, input})
+        end
+
+      {:out, expected} ->
+        receive do
+          {:out, ^pid, output} -> assert output == expected
+        end
+    end
+
+    handle_io(pid, rest)
+  end
+
+  test "exits" do
+    assert run([]) == {:ok, []}
+  end
+
+  test "halts" do
+    assert run([99]) == {:halt, [99]}
+  end
+
+  test "basic position mode instructions" do
+    assert run([1, 3, 2, 3]) == {:ok, [1, 3, 2, 5]}
+    assert run([2, 3, 2, 3]) == {:ok, [2, 3, 2, 6]}
+  end
+
+  test "basic immediate mode instructions" do
+    assert run([1101, 1, 2, 0]) == {:ok, [3, 1, 2, 0]}
+    assert run([1102, 4, 2, 0]) == {:ok, [8, 4, 2, 0]}
+  end
+
+  test "receives input" do
+    assert run([3, 1], in: 1234) == {:ok, [3, 1234]}
+  end
+
+  test "produces output" do
+    assert run([104, 77], out: 77) == {:ok, [104, 77]}
+    assert run([4, 0], out: 4) == {:ok, [4, 0]}
+  end
+
+  test "jump if non-zero" do
+    prog = [1105, 1, 4, 99, 1101, 1, 2, 7]
+    assert run(prog) == {:ok, List.replace_at(prog, 7, 3)}
+    prog = [1105, 0, 4, 99, 1101, 1, 2, 7]
+    assert run(prog) == {:halt, prog}
+
+    prog = [1005, 0, 4, 99, 1101, 1, 2, 7]
+    assert run(prog) == {:ok, List.replace_at(prog, 7, 3)}
+
+    prog = [5, 0, 9, 99, 1101, 1, 2, 7, 99, 4]
+    assert run(prog) == {:halt, List.replace_at(prog, 7, 3)}
+  end
+
+  test "jump if zero" do
+    prog = [1106, 0, 4, 99, 1101, 1, 2, 7]
+    assert run(prog) == {:ok, List.replace_at(prog, 7, 3)}
+    prog = [1106, 42, 4, 99, 1101, 1, 2, 7]
+    assert run(prog) == {:halt, prog}
+
+    prog = [1006, 9, 4, 99, 1101, 1, 2, 7, 99, 0]
+    assert run(prog) == {:halt, List.replace_at(prog, 7, 3)}
+    prog = [6, 9, 10, 99, 1101, 1, 2, 7, 99, 0, 4]
+    assert run(prog) == {:halt, List.replace_at(prog, 7, 3)}
+  end
+
+  test "compare less than" do
+    prog = [1107, 3, 8, 3]
+    assert run(prog) == {:ok, List.replace_at(prog, 3, 1)}
+    prog = [1107, 12, 8, 3]
+    assert run(prog) == {:ok, List.replace_at(prog, 3, 0)}
+
+    prog = [1007, 3, 8, 3]
+    assert run(prog) == {:ok, List.replace_at(prog, 3, 1)}
+    prog = [7, 3, 0, 3]
+    assert run(prog) == {:ok, List.replace_at(prog, 3, 1)}
+  end
+
+  test "compare equal to" do
+    prog = [1108, 4, 4, 3]
+    assert run(prog) == {:ok, List.replace_at(prog, 3, 1)}
+    prog = [1108, 5, 4, 3]
+    assert run(prog) == {:ok, List.replace_at(prog, 3, 0)}
+
+    prog = [1008, 0, 1008, 3]
+    assert run(prog) == {:ok, List.replace_at(prog, 3, 1)}
+    prog = [8, 2, 2, 3]
+    assert run(prog) == {:ok, List.replace_at(prog, 3, 1)}
+  end
+end