I get sometimes error in my tests

Questions / Help
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1

I have a suite of tests for an API app that uses mongoDB, sometimes all the tests pass but sometimes I get this error.

test index/2 OK (WorkersWeb.Api.V1.CountyControllerTest)
     test/workers_web/controllers/api/v1/county_controller_test.exs:18
     ** (Protocol.UndefinedError) protocol Enumerable not implemented for nil. This protocol is implemented for: DBConnection.PrepareStream, DBConnection.Stream, Date.Range, File.Stream, Function, GenEvent.Stream, HashDict, HashSet, IO.Stream, List, Map, MapSet, Mongo.AggregationCursor, Mongo.Cursor, Mongo.SinglyCursor, Range, Stream
     code: assert Enum.count(json["counties"]) == 3
     stacktrace:
       (elixir) /home/boris/.kiex/builds/elixir-git/lib/elixir/lib/enum.ex:1: Enumerable.impl_for!/1
       (elixir) /home/boris/.kiex/builds/elixir-git/lib/elixir/lib/enum.ex:153: Enumerable.count/1
       (elixir) lib/enum.ex:554: Enum.count/1
       test/workers_web/controllers/api/v1/county_controller_test.exs:27: (test)

The error doesn’t appear in the same place, is this some kind of race condition error where the tests is done before mongo creates the item to be tested?

2

Can you please show the test? Whatever you are doing is expecting a list by the looks of it, but in this case json["counties"] is returning nil, which is why you get the protocol error.

3

This is the test for this case

defmodule WorkersWeb.Api.V1.CountyControllerTest do
  use WorkersWeb.ConnCase
  alias Workers.Mongo, as: Wmongo
  @token "authtoken123"

  setup do
    Wmongo.delete_many!("counties", %{})

    conn = build_conn()
    |> put_req_header("accept", "application/json")
    |> put_req_header("content-type", "text/json")

    jwt = sign_and_store_user(@token)
    {:ok, conn: conn, jwt: jwt}
  end

  describe "index/2" do
    test "OK", %{conn: conn, jwt: jwt} do
      create_counties()

      conn = conn
      |> put_req_header("authorization", jwt)
      |> get("/api/v1/counties?order_by=name&order_dir=desc")

      json = Poison.decode!(conn.resp_body)

      assert Enum.count(json["counties"]) == 3
      assert Enum.map(json["counties"], &(&1["name"])) == ["Sheridan", "SABINE PASS", "SABINE OTHER"]

      co = List.first(json["counties"])
      assert Map.keys(co) == ["api_id", "name", "state_abbr"]
    end

    test "Unathorized", %{conn: conn} do
      conn = get(conn, "/api/v1/counties")

      assert conn.status == 401
      json = Poison.decode!(conn.resp_body)

      assert json["msg"] == "Please login."
    end
  end

  describe "show/2" do
    test "ok", %{conn: conn, jwt: jwt} do
      api_id = "49-033"
      Wmongo.insert_one!("counties", %{name: "Sheridan", county_api: "033", api_id: api_id, state_abbr: "WY"})

      conn = conn
      |> put_req_header("authorization", jwt)
      |> get("/api/v1/counties/#{api_id}")

      json = Poison.decode!(conn.resp_body)
      assert json["county"] == %{"api_id" => "49-033", "name" => "Sheridan", "state_abbr" => "WY"}
    end

    test "Not found", %{conn: conn, jwt: jwt} do
      conn = conn
      |> put_req_header("authorization", jwt)
      |> get("/api/v1/counties/49-333")
      json = Poison.decode!(conn.resp_body)

      assert json["error"] == "County not found"
      assert conn.status == 404
    end
  end
end

Method to create counties

  def create_counties do
    Mongo.delete_many(:mongo, "counties", %{}, [pool: DBConnection.Poolboy])
    Mongo.insert_many(:mongo, "counties", load_fixture("counties")["counties"], [pool: DBConnection.Poolboy])
  end
4

Please check I get sometimes error in my tests

5

A couple things I’m seeing.

You are using Mongo.insert_many/4 to insert your records. Try using Mongo.insert_many!/4. This will raise an error if for whatever reason the insert fails. Right now, it will just fail silently (because it currently returns {:error, reason}.

Your WorkersWeb.ConnCase module, does it use async: true by default? If so, that can cause an issue since you are not using unique collection names.

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