Validate all app properties and do not accept nil values

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

@@ -19,7 +19,7 @@ defmodule Mix.Tasks.Compile.App do
   http://www.erlang.org/doc/design_principles/applications.html
 
   ## Configuration
-  
+
   * `:app` - The application name as a binary (required)
   * `:version` - The application version as a binary (required)
 
@@ -86,51 +86,57 @@ defmodule Mix.Tasks.Compile.App do
 
   defp ensure_correct_properties(app, properties) do
     properties = Keyword.from_enum(properties)
-    properties = Keyword.put properties, :description, 
+    properties = Keyword.put properties, :description,
                              to_char_list(properties[:description] || app)
     properties = Keyword.put properties, :registered, (properties[:registered] || [])
     validate_properties(properties)
     properties
   end
 
   defp validate_properties(properties) do
-    unless nil?(properties[:description]) or is_list(properties[:description]) do
-      raise(Mix.Error, message: "Application description (:description) is not a character list (got #{inspect properties[:description]})")
-    end
-    unless nil?(properties[:id]) or is_list(properties[:id]) do
-      raise(Mix.Error, message: "Application id (:id) is not a character list (got #{inspect properties[:id]} instead)")
-    end    
-    unless nil?(properties[:vsn]) or is_list(properties[:vsn]) do
-      raise(Mix.Error, message: "Application vsn (:vsn) is not a character list (got #{inspect properties[:vsn]} instead)")
-    end
-    unless nil?(properties[:modules]) or (is_list(properties[:modules]) and Enum.all?(properties[:modules], is_atom(&1))) do
-      raise(Mix.Error, message: "Application modules (:modules) should be a list of atoms (got #{inspect properties[:modules]} instead)")
-    end
-    unless nil?(properties[:maxT]) or properties[:maxT] == :infinity or is_integer(properties[:maxT]) do
-      raise(Mix.Error, message: "Application maximum time (:maxT) is not an integer or :infinity (got #{inspect properties[:maxT]} instead)")
-    end
-    unless nil?(properties[:registered]) or is_list(properties[:registered]) and (Enum.all?(properties[:registered], is_atom(&1))) do
-      raise(Mix.Error, message: "Application registered processes (:registered) should be a list of atoms (got #{inspect properties[:registered]} instead)")
-    end
-    unless nil?(properties[:included_applications]) or (is_list(properties[:included_applications]) and Enum.all?(properties[:included_applications], is_atom(&1))) do
-      raise(Mix.Error, message: "Application included applications (:included_applications) should be a list of atoms (got #{inspect properties[:included_applications]} instead)")
-    end
-    unless nil?(properties[:applications]) or (is_list(properties[:applications]) and Enum.all?(properties[:applications], is_atom(&1))) do
-      raise(Mix.Error, message: "Application dependencies (:applications) should be a list of atoms (got #{inspect properties[:applications]} instead)")
-    end
-    unless nil?(properties[:env]) or (Keyword.keyword?(properties[:env])) do
-      raise(Mix.Error, message: "Application dependencies (:env) should be a keyword list (got #{inspect properties[:env]} instead)")
-    end
-    unless nil?(properties[:mod]) do
-      case properties[:mod] do
-        [] -> :ok
-        {module, _start_args} when is_atom(module) -> :ok
-        other ->
-          raise(Mix.Error, message: "Application callback module (:mod) should be either [] or {module, start_args} (got #{inspect properties[:mod]} instead)")
-      end          
-    end
-    unless nil?(properties[:start_phases]) or (Keyword.keyword?(properties[:start_phases])) do
-      raise(Mix.Error, message: "Application start phases (:start_phases) should be a keyword list (got #{inspect properties[:start_phases]} instead)")
+    Enum.each properties, fn
+      { :description, value } ->
+        unless is_list(value), do:
+          invalid "Application description (:description) is not a character list (got #{inspect value})"
+      { :id, value } ->
+        unless is_list(value), do:
+          invalid "Application id (:id) is not a character list (got #{inspect value} instead)"
+      { :vsn, value } ->
+        unless is_list(value), do:
+          invalid "Application vsn (:vsn) is not a character list (got #{inspect value} instead)"
+      { :maxT, value } ->
+        unless value == :infinity or is_integer(value), do:
+          invalid "Application maximum time (:maxT) is not an integer or :infinity (got #{inspect value} instead)"
+      { :modules, value } ->
+        unless is_list(value) and Enum.all?(value, is_atom(&1)), do:
+          invalid "Application modules (:modules) should be a list of atoms (got #{inspect value} instead)"
+      { :registered, value } ->
+        unless is_list(value) and Enum.all?(value, is_atom(&1)), do:
+          invalid "Application registered processes (:registered) should be a list of atoms (got #{inspect value} instead)"
+      { :included_applications, value } ->
+        unless is_list(value) and Enum.all?(value, is_atom(&1)), do:
+          invalid "Application included applications (:included_applications) should be a list of atoms (got #{inspect value} instead)"
+      { :applications, value } ->
+        unless is_list(value) and Enum.all?(value, is_atom(&1)), do:
+          invalid "Application dependencies (:applications) should be a list of atoms (got #{inspect value} instead)"
+      { :env, value } ->
+        unless Keyword.keyword?(value), do:
+          invalid "Application dependencies (:env) should be a keyword list (got #{inspect value} instead)"
+      { :start_phases, value } ->
+        unless Keyword.keyword?(value), do:
+          invalid "Application start phases (:start_phases) should be a keyword list (got #{inspect value} instead)"
+      { :mod, [] } ->
+        :ok
+      { :mod, { module, _args } } when is_atom(module) ->
+        :ok
+      { :mod, value } ->
+        invalid "Application callback module (:mod) should be either [] or {module, start_args} (got #{inspect value} instead)"
+      { key, value } ->
+        invalid "Unknown application key #{inspect key} with value #{inspect value}"
     end
   end
+
+  defp invalid(message) do
+    raise Mix.Error, message: message
+  end
 end

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

@@ -15,7 +15,7 @@ defmodule Mix.Tasks.Compile.AppTest do
     end
 
     def application do
-      [hello: 'beautiful']
+      [maxT: :infinity]
     end
   end
 
@@ -66,7 +66,7 @@ defmodule Mix.Tasks.Compile.AppTest do
       Mix.Tasks.Compile.App.run([])
       contents = File.read!("ebin/custom_project.app")
       assert contents =~ %r/0.2.0/
-      assert contents =~ %r/{hello,"beautiful"}/
+      assert contents =~ %r/{maxT,infinity}/
     end
   after
     purge [A, B, C]