Add :cd option to Mix.Shell.cmd/2 and --cd to mix cmd (#10029)

Author: wojtekmach

lib/mix/lib/mix/shell.ex

@@ -76,8 +76,12 @@ defmodule Mix.Shell do
 
   ## Options
 
+    * `:cd` - (since v1.11.0) the directory to run the command in
+
     * `:stderr_to_stdout` - redirects stderr to stdout, defaults to true
+
     * `:env` - a list of environment variables, defaults to `[]`
+
     * `:quiet` - overrides the callback to no-op
 
   """
@@ -98,7 +102,10 @@ defmodule Mix.Shell do
         []
       end
 
-    opts = [:stream, :binary, :exit_status, :hide, :use_stdio, {:env, env} | args]
+    opts =
+      [:stream, :binary, :exit_status, :hide, :use_stdio, {:env, env}] ++
+        args ++ Keyword.take(options, [:cd])
+
     port = Port.open({:spawn, shell_command(command)}, opts)
     port_read(port, callback)
   end

lib/mix/lib/mix/tasks/cmd.ex

@@ -22,6 +22,13 @@ defmodule Mix.Tasks.Cmd do
   This task is automatically reenabled, so it can be called multiple times
   with different arguments.
 
+  ## Command line options
+
+    * `--app` - limit running the command to the given app. This option
+      may be given multiple times
+
+    * `--cd` - (since v1.11.0) the directory to run the command in
+
   ## Zombie operating system processes
 
   Beware that the Erlang VM does not terminate child processes
@@ -35,27 +42,25 @@ defmodule Mix.Tasks.Cmd do
   of the `Port` module documentation.
   """
 
+  @switches [
+    app: :keep,
+    cd: :string
+  ]
+
   @impl true
   def run(args) do
-    {args, apps} = parse_apps(args, [])
+    {opts, args} = OptionParser.parse_head!(args, strict: @switches)
+    apps = Enum.map(List.wrap(opts[:app]), &String.to_atom/1)
 
     if apps == [] or Mix.Project.config()[:app] in apps do
-      case Mix.shell().cmd(Enum.join(args, " ")) do
+      cmd_opts = Keyword.take(opts, [:cd])
+
+      case Mix.shell().cmd(Enum.join(args, " "), cmd_opts) do
         0 -> :ok
         status -> exit(status)
       end
     end
 
     Mix.Task.reenable("cmd")
   end
-
-  defp parse_apps(args, apps) do
-    case args do
-      ["--app", app | tail] ->
-        parse_apps(tail, [String.to_atom(app) | apps])
-
-      args ->
-        {args, apps}
-    end
-  end
 end

lib/mix/test/mix/shell_test.exs

@@ -17,4 +17,16 @@ defmodule Mix.ShellTest do
   after
     Mix.shell(Mix.Shell.Process)
   end
+
+  test "with :cd" do
+    Mix.shell(Mix.Shell.IO)
+    tmp_dir = System.tmp_dir()
+    {pwd, 0} = System.cmd("pwd", [], cd: tmp_dir)
+
+    assert ExUnit.CaptureIO.capture_io(fn ->
+             Mix.shell().cmd("pwd", cd: tmp_dir)
+           end) == pwd
+  after
+    Mix.shell(Mix.Shell.Process)
+  end
 end

lib/mix/test/mix/tasks/cmd_test.exs

@@ -36,4 +36,16 @@ defmodule Mix.Tasks.CmdTest do
       end)
     end)
   end
+
+  test "only runs the cmd for specified apps and in specific directory" do
+    in_fixture("umbrella_dep/deps/umbrella", fn ->
+      Mix.Project.in_project(:umbrella, ".", fn _ ->
+        Mix.Task.run("cmd", ["--app", "bar", "--cd", "lib", "pwd"])
+        assert_received {:mix_shell, :info, ["==> bar"]}
+        {pwd, 0} = System.cmd("pwd", [], cd: Path.join(["apps", "bar", "lib"]))
+        assert_received {:mix_shell, :run, [^pwd]}
+        refute_received {:mix_shell, :info, ["==> foo"]}
+      end)
+    end)
+  end
 end