Load current application in compile.app

Author: josevalim

lib/mix/lib/mix/tasks/compile.app.ex

@@ -83,6 +83,9 @@ defmodule Mix.Tasks.Compile.App do
   The complete list can be found on [Erlang's application
   specification](https://www.erlang.org/doc/man/app).
 
+  From Elixir v1.17 onwards, the application .app file is also loaded
+  whenever the task runs.
+
   ## Command line options
 
     * `--force` - forces compilation regardless of modification times
@@ -167,12 +170,14 @@ defmodule Mix.Tasks.Compile.App do
 
       properties = [config_mtime: new_mtime] ++ properties
       contents = :io_lib.format("~p.~n", [{:application, app, properties}])
+      :application.load({:application, app, properties})
 
       Mix.Project.ensure_structure()
       File.write!(target, IO.chardata_to_string(contents))
       Mix.shell().info("Generated #{app} app")
       {:ok, []}
     else
+      :application.load({:application, app, current_properties})
       {:noop, []}
     end
   end

lib/mix/test/mix/tasks/compile.app_test.exs

@@ -71,12 +71,15 @@ defmodule Mix.Tasks.Compile.AppTest do
       assert Mix.Tasks.Compile.App.run([]) == {:ok, []}
 
       properties = parse_resource_file(:sample)
+      assert Application.spec(:sample, :vsn) == ~c"0.1.0"
       assert properties[:vsn] == ~c"0.1.0"
       assert properties[:modules] == [A, B]
       assert properties[:applications] == [:kernel, :stdlib, :elixir]
       refute Keyword.has_key?(properties, :compile_env)
 
+      Application.unload(:sample)
       assert Mix.Tasks.Compile.App.run([]) == {:noop, []}
+      assert Application.spec(:sample, :vsn) == ~c"0.1.0"
     end)
   end
 
@@ -114,6 +117,7 @@ defmodule Mix.Tasks.Compile.AppTest do
       Mix.Tasks.Compile.App.run([])
 
       properties = parse_resource_file(:custom_project)
+      assert Application.spec(:custom_project, :vsn) == ~c"0.2.0"
       assert properties[:vsn] == ~c"0.2.0"
       assert properties[:maxT] == :infinity
       assert properties[:optional_applications] == [:ex_unit, :mix]

lib/mix/test/mix/tasks/eval_test.exs

@@ -9,7 +9,7 @@ defmodule Mix.Tasks.EvalTest do
 
   test "does not start applications", context do
     in_tmp(context.test, fn ->
-      expr = "send self(), {:apps, Application.loaded_applications()}"
+      expr = "send self(), {:apps, Application.started_applications()}"
       Mix.Tasks.Eval.run([expr])
       assert_received {:apps, apps}
       refute List.keyfind(apps, :sample, 0)