Openapi property based testing (#172)

* first tries of property-based testing APIv3

* improve requests handling in CastAndValidate plug

* cover missing field scenario; upgrade missing field response stub

* refactor RequestsGenerator; remove stream_data dep from dev

* ignore StreamData by dialyzer; #makeCircleCIGreenAgain

* apply PR remarks

```
This PR introduces a property-based approach to APIv3 testing, with a little help of the `StreamData` framework. I also incorporated the fix/enhancement of 'the hack of the hack' introduced in #168. Shortly speaking, the request containing, from the needed fields, only data, alert/body and alert/title fields, was matched against SilentNotification schema, what has been leading to improper Unexpected field: alert error.

I also improved the `ControllersHelper.missing_field_response` helper function to better reflect possible error messages we can encounter during tests, based on the API version being used.
```

.dialyzer_ignore.exs

@@ -3,5 +3,6 @@
   ~r/Function :asn1ct.compile\/2 does not exist/,
   ~r/lib\/mix\//,
   ~r/test\/support\/mix\//,
+  ~r/test\/support\/requests_generator\.ex/,
   {"test/support/api.ex"}
 ]

lib/mongoose_push_web/plugs/cast_and_validate.ex

@@ -34,6 +34,19 @@ defmodule MongoosePushWeb.Plug.CastAndValidate do
   # "Failed to cast value to one of: [] (no schemas provided)", instead of something more meaningful.
   # Here we avoid it by manual modification of the pattern the request is matched against,
   # so the framework can serve us as expected.
+  defp update_schema_and_do_call(
+         conn = %{params: %{"alert" => _, "data" => _}},
+         opts = %{operation_id: operation_id}
+       ) do
+    new_schema = %OpenApiSpex.Reference{
+      "$ref": "#/components/schemas/Request.SendNotification.Deep.MixedNotification"
+    }
+
+    conn
+    |> update_schema(operation_id, new_schema)
+    |> OpenApiSpex.Plug.CastAndValidate.call(opts)
+  end
+
   defp update_schema_and_do_call(
          conn = %{params: %{"data" => _}},
          opts = %{operation_id: operation_id}

mix.exs

@@ -61,7 +61,8 @@ defmodule MongoosePush.Mixfile do
       {:telemetry, "~>0.4.1"},
       {:telemetry_metrics, "~> 0.5"},
       {:telemetry_metrics_prometheus_core, "~> 0.4"},
-      {:logfmt, "~>3.3"}
+      {:logfmt, "~>3.3"},
+      {:stream_data, "~> 0.5", only: :test}
     ]
   end
 

mix.lock

@@ -50,6 +50,7 @@
   "ranch": {:hex, :ranch, "1.7.1", "6b1fab51b49196860b733a49c07604465a47bdb78aa10c1c16a3d199f7f8c881", [:rebar3], [], "hexpm", "451d8527787df716d99dc36162fca05934915db0b6141bbdac2ea8d3c7afc7d7"},
   "sparrow": {:git, "https://github.com/esl/sparrow.git", "b1896ca4fb0ca18369dd62de3d4c82f14f5bc66e", [ref: "b1896ca"]},
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.5", "6eaf7ad16cb568bb01753dbbd7a95ff8b91c7979482b95f38443fe2c8852a79b", [:make, :mix, :rebar3], [], "hexpm", "13104d7897e38ed7f044c4de953a6c28597d1c952075eb2e328bc6d6f2bfc496"},
+  "stream_data": {:hex, :stream_data, "0.5.0", "b27641e58941685c75b353577dc602c9d2c12292dd84babf506c2033cd97893e", [:mix], [], "hexpm", "012bd2eec069ada4db3411f9115ccafa38540a3c78c4c0349f151fc761b9e271"},
   "telemetry": {:hex, :telemetry, "0.4.1", "ae2718484892448a24470e6aa341bc847c3277bfb8d4e9289f7474d752c09c7f", [:rebar3], [], "hexpm", "4738382e36a0a9a2b6e25d67c960e40e1a2c95560b9f936d8e29de8cd858480f"},
   "telemetry_metrics": {:hex, :telemetry_metrics, "0.5.0", "1b796e74add83abf844e808564275dfb342bcc930b04c7577ab780e262b0d998", [:mix], [{:telemetry, "~> 0.4", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "31225e6ce7a37a421a0a96ec55244386aec1c190b22578bd245188a4a33298fd"},
   "telemetry_metrics_prometheus_core": {:hex, :telemetry_metrics_prometheus_core, "0.4.0", "0860e53746f4554cf453a5217a3d2648a6d3a074ae01a21869a3963c54b1d5bc", [:mix], [{:telemetry, "~> 0.4", [hex: :telemetry, repo: "hexpm", optional: false]}, {:telemetry_metrics, "~> 0.5", [hex: :telemetry_metrics, repo: "hexpm", optional: false]}], "hexpm", "912e4c4421477bfb930a19a8de5b2eb967c2700880698c6d80706b8bc32532bf"},

test/mongoose_push_web/controllers/api_v1_notification_controller_test.exs

@@ -30,7 +30,7 @@ defmodule MongoosePushWeb.APIv1NotificationControllerTest do
       conn = post(conn, "/v1/notification/666", body)
 
       assert json_response(conn, 422) ==
-               ControllersHelper.missing_field_response(unquote(dropped))
+               ControllersHelper.missing_field_response(:v1, unquote(dropped))
     end
   end
 

test/mongoose_push_web/controllers/api_v2_notification_controller_test.exs

@@ -30,7 +30,7 @@ defmodule MongoosePushWeb.APIv2NotificationControllerTest do
       conn = post(conn, "/v2/notification/654321", body)
 
       assert json_response(conn, 422) ==
-               ControllersHelper.missing_field_response(unquote(dropped))
+               ControllersHelper.missing_field_response(:v2, unquote(dropped))
     end
   end
 
@@ -81,7 +81,7 @@ defmodule MongoosePushWeb.APIv2NotificationControllerTest do
       conn = post(conn, "/v2/notification/654321", body)
 
       assert json_response(conn, 422) ==
-               ControllersHelper.missing_field_response(unquote(missing))
+               ControllersHelper.missing_field_response(:v2, unquote(missing))
     end
   end
 
@@ -124,8 +124,8 @@ defmodule MongoosePushWeb.APIv2NotificationControllerTest do
 
     assert json_response(conn, 422) ==
              Map.merge(
-               ControllersHelper.missing_field_response("service"),
-               ControllersHelper.missing_field_response("alert"),
+               ControllersHelper.missing_field_response(:v2, "service"),
+               ControllersHelper.missing_field_response(:v2, "alert"),
                fn _k, v1, v2 -> v1 ++ v2 end
              )
   end

test/mongoose_push_web/controllers/api_v3_notification_controller_test.exs

@@ -1,5 +1,7 @@
 defmodule MongoosePushWeb.APIv3NotificationControllerTest do
   alias MongoosePushWeb.Support.ControllersHelper
+  alias MongoosePushWeb.Support.RequestsGenerator
+  use ExUnitProperties
   use MongoosePushWeb.ConnCase, async: true
   import Mox
 
@@ -31,7 +33,7 @@ defmodule MongoosePushWeb.APIv3NotificationControllerTest do
       conn = post(conn, "/v3/notification/123456", body)
 
       assert json_response(conn, 422) ==
-               ControllersHelper.missing_field_response(unquote(dropped))
+               ControllersHelper.missing_field_response(:v3, unquote(dropped))
     end
   end
 
@@ -83,7 +85,7 @@ defmodule MongoosePushWeb.APIv3NotificationControllerTest do
       conn = post(conn, "/v3/notification/123456", body)
 
       assert json_response(conn, 422) ==
-               ControllersHelper.missing_field_response(unquote(missing))
+               ControllersHelper.missing_field_response(:v3, unquote(missing))
     end
   end
 
@@ -126,8 +128,8 @@ defmodule MongoosePushWeb.APIv3NotificationControllerTest do
 
     assert json_response(conn, 422) ==
              Map.merge(
-               ControllersHelper.missing_field_response("service"),
-               ControllersHelper.missing_field_response("alert"),
+               ControllersHelper.missing_field_response(:v3, "service"),
+               ControllersHelper.missing_field_response(:v3, "alert"),
                fn _k, v1, v2 -> v1 ++ v2 end
              )
   end
@@ -816,6 +818,35 @@ defmodule MongoosePushWeb.APIv3NotificationControllerTest do
     post_and_assert(conn, device_id, expected_device_id, request, expected_request)
   end
 
+  property "APIv3 notification decoder property-based test", %{conn: conn} do
+    check all(
+            mandatory <- RequestsGenerator.mandatory_fields(),
+            optionals <- RequestsGenerator.optional_fields(),
+            device_id <- RequestsGenerator.device_id()
+          ) do
+      request = Map.merge(mandatory, optionals, fn _k, v1, v2 -> Map.merge(v1, v2) end)
+      expected_device_id = device_id
+      expected_request = create_expected_request(request)
+      post_and_assert(conn, device_id, expected_device_id, request, expected_request)
+    end
+  end
+
+  property "APIv3 notification with dropped one mandatory field", %{conn: conn} do
+    check all(
+            mandatory <- RequestsGenerator.mandatory_fields(),
+            optionals <- RequestsGenerator.optional_fields(),
+            device_id <- RequestsGenerator.device_id(),
+            dropped <- RequestsGenerator.mandatory_field()
+          ) do
+      request =
+        Map.merge(mandatory, optionals, fn _k, v1, v2 -> Map.merge(v1, v2) end)
+        |> drop_field(dropped)
+
+      conn = post(conn, "/v3/notification/#{device_id}", Jason.encode!(request))
+      assert json_response(conn, 422) == ControllersHelper.missing_field_response(:v3, dropped)
+    end
+  end
+
   defp post_and_assert(conn, device_id, expected_device_id, request, expected_request) do
     expect(MongoosePush.Notification.MockImpl, :push, fn device_id, request ->
       assert request == expected_request
@@ -838,4 +869,51 @@ defmodule MongoosePushWeb.APIv3NotificationControllerTest do
 
     assert json_response(conn, number) == %{"reason" => to_string(error_reason)}
   end
+
+  defp create_expected_request(request) do
+    %{
+      alert: fetch_alert(request["alert"]),
+      data: request["data"],
+      mode: fetch_enum_field(request["mode"]),
+      service: fetch_enum_field(request["service"]),
+      priority: fetch_enum_field(request["priority"]),
+      mutable_content: fetch_mutable_content(request["mutable_content"]),
+      tags: request["tags"],
+      topic: request["topic"],
+      time_to_live: request["time_to_live"]
+    }
+    |> drop_nil_values()
+  end
+
+  defp fetch_alert(alert) do
+    %{
+      body: alert["body"],
+      title: alert["title"],
+      badge: alert["badge"],
+      click_action: alert["click_action"],
+      tag: alert["tag"],
+      sound: alert["sound"]
+    }
+    |> drop_nil_values()
+  end
+
+  defp fetch_enum_field(nil), do: nil
+  defp fetch_enum_field(string), do: String.to_existing_atom(string)
+
+  defp fetch_mutable_content(nil), do: false
+  defp fetch_mutable_content(val), do: val
+
+  defp drop_nil_values(map) do
+    map
+    |> Enum.filter(fn {_, v} -> v != nil end)
+    |> Map.new()
+  end
+
+  defp drop_field(map, field) when field in ["body", "title"] do
+    Kernel.update_in(map, ["alert"], fn _ -> Map.drop(map["alert"], [field]) end)
+  end
+
+  defp drop_field(map, field) do
+    Map.drop(map, [field])
+  end
 end

test/support/controllers_helper.ex

@@ -66,7 +66,19 @@ defmodule MongoosePushWeb.Support.ControllersHelper do
     }
   end
 
-  def missing_field_response(field) do
+  def missing_field_response(api, field) when api in [:v2, :v3] and field in ["body", "title"] do
+    %{
+      "errors" => [
+        %{
+          "message" => "Missing field: #{field}",
+          "source" => %{"pointer" => "/alert/#{field}"},
+          "title" => "Invalid value"
+        }
+      ]
+    }
+  end
+
+  def missing_field_response(_api, field) do
     %{
       "errors" => [
         %{

test/support/requests_generator.ex

@@ -0,0 +1,77 @@
+defmodule MongoosePushWeb.Support.RequestsGenerator do
+  # APIv2/3 requests
+  def mandatory_fields() do
+    StreamData.fixed_map(%{
+      "alert" =>
+        StreamData.fixed_map(%{
+          "title" => nonempty_string(),
+          "body" => nonempty_string()
+        }),
+      "service" => service()
+    })
+  end
+
+  def optional_fields() do
+    StreamData.optional_map(%{
+      "alert" =>
+        StreamData.optional_map(%{
+          "badge" => positive_integer(),
+          "click_action" => nonempty_string(),
+          "tag" => nonempty_string(),
+          "sound" => nonempty_string()
+        }),
+      "data" => data(),
+      "mode" => mode(),
+      "priority" => priority(),
+      "mutable_content" => boolean(),
+      "tags" => tags(),
+      "topic" => nonempty_string(),
+      "time_to_live" => positive_integer()
+    })
+  end
+
+  def device_id() do
+    nonempty_string()
+  end
+
+  def mandatory_field() do
+    one_of_strings([:service, :title, :body])
+  end
+
+  # basic types
+  defp nonempty_string() do
+    StreamData.string(:alphanumeric, min_length: 1)
+  end
+
+  defp positive_integer() do
+    StreamData.positive_integer()
+  end
+
+  defp boolean() do
+    StreamData.one_of([false, true])
+  end
+
+  defp tags() do
+    StreamData.list_of(nonempty_string(), min_length: 1, max_length: 5)
+  end
+
+  defp priority() do
+    one_of_strings([:normal, :high])
+  end
+
+  defp service() do
+    one_of_strings([:apns, :fcm])
+  end
+
+  defp mode() do
+    one_of_strings([:prod, :dev])
+  end
+
+  defp data() do
+    StreamData.map_of(StreamData.string(:ascii), StreamData.string(:ascii))
+  end
+
+  defp one_of_strings(list_of_atoms) do
+    StreamData.map(StreamData.one_of(list_of_atoms), &Kernel.to_string/1)
+  end
+end