Add introspection for deprecated args/input fields

Absinthe already supported deprecating args/input fields and this
PR exposes that in the introspection query to match the spec.

Also some tests were added for deprecating stuff.

See graphql/graphql-spec#805 for the spec update

lib/absinthe/type/built_ins/introspection.ex

@@ -218,11 +218,21 @@ defmodule Absinthe.Type.BuiltIns.Introspection do
 
     field :input_fields,
       type: list_of(:__inputvalue),
+      args: [
+        include_deprecated: [
+          type: :boolean,
+          default_value: false
+        ]
+      ],
       resolve: fn
-        _, %{source: %Absinthe.Type.InputObject{fields: fields}} ->
+        %{include_deprecated: show_deprecated},
+        %{source: %Absinthe.Type.InputObject{fields: fields}} ->
           input_fields =
             fields
             |> Map.values()
+            |> Enum.filter(fn %{deprecation: is_deprecated} ->
+              !is_deprecated || (is_deprecated && show_deprecated)
+            end)
             |> Enum.sort_by(& &1.identifier)
 
           {:ok, input_fields}
@@ -253,10 +263,19 @@ defmodule Absinthe.Type.BuiltIns.Introspection do
 
     field :args,
       type: list_of(:__inputvalue),
-      resolve: fn _, %{source: %{args: args}} ->
+      args: [
+        include_deprecated: [
+          type: :boolean,
+          default_value: false
+        ]
+      ],
+      resolve: fn %{include_deprecated: show_deprecated}, %{source: %{args: args}} ->
         args =
           args
           |> Map.values()
+          |> Enum.filter(fn %{deprecation: is_deprecated} ->
+            !is_deprecated || (is_deprecated && show_deprecated)
+          end)
           |> Enum.sort_by(& &1.identifier)
 
         {:ok, args}
@@ -326,6 +345,26 @@ defmodule Absinthe.Type.BuiltIns.Introspection do
         _, %{source: _} ->
           {:ok, nil}
       end
+
+    field :is_deprecated,
+      type: :boolean,
+      resolve: fn
+        _, %{source: %{deprecation: nil}} ->
+          {:ok, false}
+
+        _, _ ->
+          {:ok, true}
+      end
+
+    field :deprecation_reason,
+      type: :string,
+      resolve: fn
+        _, %{source: %{deprecation: nil}} ->
+          {:ok, nil}
+
+        _, %{source: %{deprecation: dep}} ->
+          {:ok, dep.reason}
+      end
   end
 
   object :__enumvalue, name: "__EnumValue" do

test/absinthe/type/deprecation_test.exs

@@ -30,6 +30,16 @@ defmodule Absinthe.Type.DeprecationTest do
 
       field :address, :string, deprecate: true
     end
+
+    enum :colors do
+      value :red, deprecate: true
+      value :blue, deprecate: "This isn't supported"
+    end
+
+    input_object :contact_input do
+      field :email, non_null(:string), deprecate: true
+      field :name, non_null(:string), deprecate: "This isn't supported"
+    end
   end
 
   describe "fields" do
@@ -51,4 +61,24 @@ defmodule Absinthe.Type.DeprecationTest do
       assert nil == field.args.source.deprecation.reason
     end
   end
+
+  describe "enum values" do
+    test "can be deprecated" do
+      enum_values = TestSchema.__absinthe_type__(:colors).values
+      assert Type.deprecated?(enum_values.blue)
+      assert "This isn't supported" == enum_values.blue.deprecation.reason
+      assert Type.deprecated?(enum_values.red)
+      assert nil == enum_values.red.deprecation.reason
+    end
+  end
+
+  describe "input fields values" do
+    test "can be deprecated" do
+      input = TestSchema.__absinthe_type__(:contact_input)
+      assert Type.deprecated?(input.fields.name)
+      assert "This isn't supported" == input.fields.name.deprecation.reason
+      assert Type.deprecated?(input.fields.email)
+      assert nil == input.fields.email.deprecation.reason
+    end
+  end
 end