Add inference when using dependency injection via module attribute

lib/elixir_sense/core/binding.ex

@@ -154,6 +154,45 @@ defmodule ElixirSense.Core.Binding do
     end
   end
 
+  # dependency injection
+  def do_expand(env, {:call, {:atom, Application}, fun, args}, stack)
+      when fun in ~w(compile_env!)a do
+    # `Application.compile_env!/2` underneath works like `fetch_env!/2`
+    do_expand(env, {:call, {:atom, Application}, :fetch_env!, args}, stack)
+  end
+
+  def do_expand(env, {:call, {:atom, Application}, fun, args}, stack)
+      when fun in ~w(compile_env)a do
+    # `Application.compile_env/3` underneath works like `get_env/3`
+    do_expand(env, {:call, {:atom, Application}, :get_env, args}, stack)
+  end
+
+  def do_expand(env, {:call, {:atom, Application}, fun, args}, stack)
+      when fun in ~w(get_env fetch_env!)a do
+    try do
+      expanded_args =
+        args
+        |> Enum.map(&expand(env, &1, stack))
+        |> Enum.map(&elem(&1, 1))
+
+      mod = apply(Application, fun, expanded_args)
+
+      case mod do
+        :error ->
+          :none
+
+        mod when is_atom(mod) ->
+          {:atom, mod}
+
+        _ ->
+          nil
+      end
+    rescue
+      _ ->
+        :none
+    end
+  end
+
   # remote call
   def do_expand(env, {:call, target, function, arguments}, stack) do
     if :none in arguments do

test/elixir_sense/core/binding_test.exs

@@ -11,6 +11,70 @@ defmodule ElixirSense.Core.BindingTest do
   @env %Binding{}
 
   describe "expand" do
+    def build_dependency_injection_binding(fetcher \\ :get_env, default_value \\ nil)
+        when is_atom(default_value) do
+      arguments = [
+        atom: :elixir_sense,
+        atom: :some_attribute
+      ]
+
+      arguments = if(default_value, do: arguments ++ [{:atom, default_value}], else: arguments)
+
+      attribute_info = %AttributeInfo{
+        name: :some_module,
+        type: {:call, {:atom, Application}, fetcher, arguments}
+      }
+
+      Map.put(@env, :attributes, [
+        attribute_info
+      ])
+    end
+
+    test "misconfigured dependency injection" do
+      Application.delete_env(:elixir_sense, :some_attribute)
+
+      unsafe_fetchers = [:fetch_env!, :compile_env!]
+      safe_fetchers = [:get_env, :compile_env]
+
+      Enum.each(unsafe_fetchers, fn fetcher ->
+        assert :none ==
+                 Binding.expand(
+                   build_dependency_injection_binding(fetcher),
+                   {:attribute, :some_module}
+                 )
+      end)
+
+      Enum.each(safe_fetchers, fn fetcher ->
+        assert {:atom, nil} ==
+                 Binding.expand(
+                   build_dependency_injection_binding(fetcher),
+                   {:attribute, :some_module}
+                 )
+      end)
+    end
+
+    test "dependency injection without default value" do
+      Application.put_env(:elixir_sense, :some_attribute, ElixirSenseExample.SameModule)
+
+      fetchers = [:get_env, :fetch_env!, :compile_env, :compile_env!]
+
+      Enum.each(fetchers, fn fetcher ->
+        assert {:atom, ElixirSenseExample.SameModule} ==
+                 Binding.expand(
+                   build_dependency_injection_binding(fetcher),
+                   {:attribute, :some_module}
+                 )
+      end)
+    end
+
+    test "dependency injection with default value" do
+      assert {:atom, ElixirSenseExample.SameModule} ==
+               Binding.expand(
+                 build_dependency_injection_binding(:get_env, ElixirSenseExample.SameModule),
+                 {:attribute, :some_module}
+               )
+    end
+
     test "map" do
       assert {:map, [abc: nil, cde: {:variable, :a}], nil} ==
                Binding.expand(@env, {:map, [abc: nil, cde: {:variable, :a}], nil})

test/elixir_sense/core/metadata_builder_test.exs

@@ -38,10 +38,26 @@ defmodule ElixirSense.Core.MetadataBuilderTest do
           IO.puts @inner_attr
         end
         IO.puts ""
+        @otherattribute Application.get_env(:elixir_sense, :some_attribute, InnerModule)
       end
       """
       |> string_to_state
 
+    assert get_line_attributes(state, 10) == [
+             %ElixirSense.Core.State.AttributeInfo{
+               name: :myattribute,
+               positions: [{2, 3}, {3, 11}],
+               type: {:atom, String}
+             },
+             %AttributeInfo{
+               name: :otherattribute,
+               positions: [{10, 3}],
+               type:
+                 {:call, {:atom, Application}, :get_env,
+                  [atom: :elixir_sense, atom: :some_attribute, atom: MyModule.InnerModule]}
+             }
+           ]
+
     assert get_line_attributes(state, 3) == [
              %AttributeInfo{
                name: :myattribute,

test/elixir_sense/providers/suggestion/complete_test.exs

@@ -838,6 +838,71 @@ defmodule ElixirSense.Providers.Suggestion.CompleteTest do
            ] = expand('S.my_f', env)
   end
 
+  test "complete remote funs from injected module" do
+    env = %Env{
+      scope_module: MyModule,
+      mods_and_funs: %{
+        {Some.OtherModule, nil, nil} => %ModFunInfo{type: :defmodule},
+        {Some.OtherModule, :my_fun_other_pub, nil} => %ModFunInfo{type: :def},
+        {Some.OtherModule, :my_fun_other_pub, 1} => %ModFunInfo{
+          type: :def,
+          params: [[{:some, [], nil}]]
+        },
+        {Some.OtherModule, :my_fun_other_priv, nil} => %ModFunInfo{type: :defp},
+        {Some.OtherModule, :my_fun_other_priv, 1} => %ModFunInfo{
+          type: :defp,
+          params: [[{:some, [], nil}]]
+        }
+      },
+      attributes: [
+        %AttributeInfo{
+          name: :get_module,
+          type:
+            {:call, {:atom, Application}, :get_env,
+             [atom: :elixir_sense, atom: :an_attribute, atom: Some.OtherModule]}
+        },
+        %AttributeInfo{
+          name: :compile_module,
+          type:
+            {:call, {:atom, Application}, :compile_env,
+             [atom: :elixir_sense, atom: :an_attribute, atom: Some.OtherModule]}
+        },
+        %AttributeInfo{
+          name: :fetch_module,
+          type:
+            {:call, {:atom, Application}, :fetch_env!,
+             [atom: :elixir_sense, atom: :other_attribute]}
+        },
+        %AttributeInfo{
+          name: :compile_bang_module,
+          type:
+            {:call, {:atom, Application}, :compile_env!,
+             [atom: :elixir_sense, atom: :other_attribute]}
+        }
+      ]
+    }
+
+    assert [
+             %{name: "my_fun_other_pub", origin: "Some.OtherModule"}
+           ] = expand('@get_module.my_f', env)
+
+    assert [
+             %{name: "my_fun_other_pub", origin: "Some.OtherModule"}
+           ] = expand('@compile_module.my_f', env)
+
+    Application.put_env(:elixir_sense, :other_attribute, Some.OtherModule)
+
+    assert [
+             %{name: "my_fun_other_pub", origin: "Some.OtherModule"}
+           ] = expand('@fetch_module.my_f', env)
+
+    assert [
+             %{name: "my_fun_other_pub", origin: "Some.OtherModule"}
+           ] = expand('@compile_bang_module.my_f', env)
+  after
+    Application.delete_env(:elixir_sense, :other_attribute)
+  end
+
   test "complete modules" do
     env = %Env{
       scope_module: MyModule,