Implement poncho.test task.

lib/mix/tasks/poncho.test.ex

@@ -5,15 +5,65 @@ defmodule Mix.Tasks.Poncho.Test do
   @preferred_cli_env :test
   @moduledoc """
   Tests all mix projects in the current directory, e. g., when run from a root
-  directory of a poncho project, it test the whole project.
+  directory of a poncho project, it tests the whole project.
+
+  The tested projects are loaded, examined, and sorted, so that the testing
+  starts from the leaves of the dependency tree, moving back to the DAG root,
+  which is -- in case of a nerves project -- a firmware module. This prevents
+  repeated project building (in :prod and :test env), loading, and polluting VM
+  runtime.
   """
 
   def run(args) do
-    unless System.get_env("MIX_ENV") || Mix.env == :test do
-      Mix.raise "\"mix poncho.test\" is running on environment \"#{Mix.env}\". If you are " <>
-        "running tests along another task, please set MIX_ENV explicitly"
-    end
+    {:ok, ls} = File.ls()
+
+    ls
+    |> Enum.filter(&File.dir?/1)
+    |> Enum.filter(&mixproject?/1)
+    |> Enum.map(&to_dep/1)
+    |> Enum.map(&to_loaded/1)
+    |> Mix.Dep.Converger.topological_sort
+    |> Enum.map(&(do_test(&1, args)))
+  end
+
+  defp mixproject?(dir) do
+    File.regular?("#{dir}/#{mixfile()}")
+  end
+
+  defp to_dep(dir) do
+
+    path = Path.expand(dir)
+    build = Path.join(path, "_build")
 
-    IO.puts "implement me"
+    %Mix.Dep{
+      scm: Mix.SCM.Path,
+      app: String.to_atom(dir),
+      manager: :mix,
+      status: {:ok, nil},
+      opts: [
+        path: path,
+        dest: path,
+        build: build,
+        env: Mix.env(),
+      ]
+    }
   end
+
+  defp to_loaded(%Mix.Dep{} = dep) do
+    dep = Mix.Dep.Loader.load(dep, nil)
+    ddeps = Enum.filter(dep.deps, fn dep ->
+      Mix.Dep.available?(dep)
+    end)
+
+    %{dep | deps: ddeps}
+  end
+
+  defp do_test(%Mix.Dep{app: app}, args) do
+    Mix.shell.info("==> #{app}")
+    Mix.Project.in_project(app, Atom.to_string(app), fn _module ->
+      Mix.Task.run("test", args)
+    end)
+  end
+
+  defp mixfile(), do: System.get_env("MIX_EXS") || "mix.exs"
 end