Add appsignal.demo mix task (#69)

* Add appsignal.demo task

As currently present in our Ruby gem as well:
appsignal/appsignal-ruby#199

The "appsignal.demo" command is useful for debugging AppSignal and
testing AppSignal.

It sends a demonstration sample for an error and a performance issue.
They will show up on AppSignal.com as demonstration samples with a small
special UI attached to them describing their purpose.

Debugging manual referencing the "demo" command:
http://docs.appsignal.com/support/debugging.html

* Use Application.ensure_all_started/1 in demo task

* Remove Appsignal.Demo.transmit/0, move calls to mix task

* Don't use ErrorHandler.format_stack/1 in Demo

* Pipe transaction through functions in Demo.create_transaction_error_request

* Wrap environment data in an environment map in Demo

* Print message after sending demo data

* Link to the full URL in the demo task

* Fix Elixir 1.4 compilation warnings

lib/appsignal/demo.ex

@@ -0,0 +1,51 @@
+defmodule Appsignal.Demo do
+  import Appsignal.Instrumentation.Helpers, only: [instrument: 4]
+
+  @doc false
+  def create_transaction_error_request do
+    create_demo_transaction()
+    |> Appsignal.Transaction.set_error(
+      "TestError",
+      "Hello world! This is an error used for demonstration purposes.",
+      System.stacktrace
+    )
+    |> finish_demo_transaction()
+  end
+
+  @doc false
+  def create_transaction_performance_request do
+    transaction = create_demo_transaction()
+
+    instrument(transaction, "template.render", "Rendering something slow", fn() ->
+      :timer.sleep(1000)
+      instrument(transaction, "ecto.query", "Slow query", fn() ->
+        :timer.sleep(300)
+      end)
+      instrument(transaction, "ecto.query", "Slow query", fn() ->
+        :timer.sleep(500)
+      end)
+      instrument(transaction, "template.render", "Rendering something slow", fn() ->
+        :timer.sleep(100)
+      end)
+    end)
+
+    finish_demo_transaction(transaction)
+  end
+
+  defp create_demo_transaction do
+    Appsignal.Transaction.start(
+      Appsignal.Transaction.generate_id,
+      :http_request
+    )
+    |> Appsignal.Transaction.set_action("DemoController#hello")
+    |> Appsignal.Transaction.set_meta_data("demo_sample", "true")
+    |> Appsignal.Transaction.set_sample_data(
+      "environment", %{request_path: "/hello", method: "GET"}
+    )
+  end
+
+  defp finish_demo_transaction(transaction) do
+    Appsignal.Transaction.finish(transaction)
+    :ok = Appsignal.Transaction.complete(transaction)
+  end
+end

lib/appsignal/instrumentation/helpers.ex

@@ -34,10 +34,10 @@ defmodule Appsignal.Instrumentation.Helpers do
   import Appsignal.Instrumentation.Helpers, only: [instrument: 4]
 
   def index(conn, _params) do
-  result = instrument(conn, "net.http", "Some slow backend call", fn() ->
-  Backend.get_result()
-  end
-  json conn, result
+    result = instrument conn, "net.http", "Some slow backend call", fn() ->
+      Backend.get_result()
+    end
+    json conn, result
   end
   ```
 

lib/mix/tasks/appsignal.demo.ex

@@ -0,0 +1,15 @@
+defmodule Mix.Tasks.Appsignal.Demo do
+  require Logger
+  use Mix.Task
+
+  @shortdoc "Perform and send a demonstration error and performance issue to AppSignal."
+
+  def run(_args) do
+    {:ok, _} = Application.ensure_all_started(:appsignal)
+    Appsignal.Demo.create_transaction_performance_request
+    Appsignal.Demo.create_transaction_error_request
+    Appsignal.stop(nil)
+    Logger.info("Demonstration sample data sent!")
+    Logger.info("It may take about a minute for the data to appear on https://appsignal.com/accounts")
+  end
+end

mix.exs

@@ -8,7 +8,6 @@ defmodule Mix.Tasks.Compile.Appsignal do
   end
 end
 
-
 defmodule Appsignal.Mixfile do
   use Mix.Project
 
@@ -57,7 +56,6 @@ defmodule Appsignal.Mixfile do
       {:poison, "~> 2.1"},
       {:decorator, "~> 1.0"},
       {:phoenix, "~> 1.2.0", optional: true, only: :test_phoenix},
-
       {:mock, "~> 0.1.1", only: [:test, :test_phoenix]},
       {:ex_doc, "~> 0.12", only: :dev}
     ]

mix.lock

@@ -3,7 +3,7 @@
   "ex_doc": {:hex, :ex_doc, "0.14.3", "e61cec6cf9731d7d23d254266ab06ac1decbb7651c3d1568402ec535d387b6f7", [:mix], [{:earmark, "~> 1.0", [hex: :earmark, optional: false]}]},
   "meck": {:hex, :meck, "0.8.4", "59ca1cd971372aa223138efcf9b29475bde299e1953046a0c727184790ab1520", [:make, :rebar], []},
   "mime": {:hex, :mime, "1.0.1", "05c393850524767d13a53627df71beeebb016205eb43bfbd92d14d24ec7a1b51", [:mix], []},
-  "mock": {:hex, :mock, "0.1.3", "657937b03f88fce89b3f7d6becc9f1ec1ac19c71081aeb32117db9bc4d9b3980", [:mix], [{:meck, "~> 0.8.2", [hex: :meck, optional: false]}]},
+  "mock": {:hex, :mock, "0.2.0", "5991877be6bb514b647dbd6f4869bc12bd7f2829df16e86c98d6108f966d34d7", [:mix], [{:meck, "~> 0.8.2", [hex: :meck, optional: false]}]},
   "phoenix": {:hex, :phoenix, "1.2.1", "6dc592249ab73c67575769765b66ad164ad25d83defa3492dc6ae269bd2a68ab", [:mix], [{:cowboy, "~> 1.0", [hex: :cowboy, optional: true]}, {:phoenix_pubsub, "~> 1.0", [hex: :phoenix_pubsub, optional: false]}, {:plug, "~> 1.1", [hex: :plug, optional: false]}, {:poison, "~> 1.5 or ~> 2.0", [hex: :poison, optional: false]}]},
   "phoenix_pubsub": {:hex, :phoenix_pubsub, "1.0.1", "c10ddf6237007c804bf2b8f3c4d5b99009b42eca3a0dfac04ea2d8001186056a", [:mix], []},
   "plug": {:hex, :plug, "1.2.2", "cfbda521b54c92ab8ddffb173fbaabed8d8fc94bec07cd9bb58a84c1c501b0bd", [:mix], [{:cowboy, "~> 1.0", [hex: :cowboy, optional: true]}, {:mime, "~> 1.0", [hex: :mime, optional: false]}]},

test/demo_test.exs

@@ -0,0 +1,28 @@
+defmodule AppsignalDemoTest do
+  use ExUnit.Case
+  import Mock
+  alias Appsignal.{Transaction, TransactionRegistry}
+
+  test_with_mock "sends a demonstration error", Appsignal.Transaction, [:passthrough], [] do
+    Appsignal.Demo.create_transaction_error_request
+
+    t = %Transaction{} = TransactionRegistry.lookup(self())
+    assert called Appsignal.Transaction.set_action(t, "DemoController#hello")
+    assert called Appsignal.Transaction.set_error(t, "TestError", "Hello world! This is an error used for demonstration purposes.", [])
+    assert called Appsignal.Transaction.set_meta_data(t, "demo_sample", "true")
+    assert called Appsignal.Transaction.finish(t)
+    assert called Appsignal.Transaction.complete(t)
+  end
+
+  test_with_mock "sends a performance issue", Appsignal.Transaction, [:passthrough], [] do
+    Appsignal.Demo.create_transaction_performance_request
+
+    t = %Transaction{} = TransactionRegistry.lookup(self())
+    assert called Appsignal.Transaction.set_action(t, "DemoController#hello")
+    assert called Appsignal.Transaction.set_meta_data(t, "demo_sample", "true")
+    assert called Appsignal.Transaction.start_event(t)
+    assert called Appsignal.Transaction.finish_event(t, "template.render", "Rendering something slow", "", 0)
+    assert called Appsignal.Transaction.finish(t)
+    assert called Appsignal.Transaction.complete(t)
+  end
+end