Remove exporter race-condition on tests (#44)

Default exporter immediately attempts on start connect to
`:otel-collector` default port. As we don't have any collector running
on our test environment, this results in a few warnings. That's not an
issue in itself, as code immediately switches to another export, but
creates a lot of noise.

This patch moves the exporter setup to `config/test.exs`, essentially
removing the need to restart opentelemetry applicationn for each test
case. The only work setup blocks do is update the exporter's target pid.

The processor was changed to simple mode, available now, which also remove
another vector of (unlikely but theoretically possible) race-conditions.

instrumentation/opentelemetry_ecto/config/test.exs

@@ -11,4 +11,4 @@ config :opentelemetry_ecto, OpentelemetryEcto.TestRepo,
   pool: Ecto.Adapters.SQL.Sandbox
 
 config :opentelemetry,
-  processors: [{:otel_batch_processor, %{scheduled_delay_ms: 1}}]
+  processors: [{:otel_simple_processor, %{}}]

instrumentation/opentelemetry_ecto/test/opentelemetry_ecto_test.exs

@@ -15,16 +15,7 @@ defmodule OpentelemetryEctoTest do
   end
 
   setup do
-    :application.stop(:opentelemetry)
+    :otel_simple_processor.set_exporter(:otel_exporter_pid, self())
-    :application.set_env(:opentelemetry, :tracer, :otel_tracer_default)
-
-    :application.set_env(:opentelemetry, :processors, [
-      {:otel_batch_processor, %{scheduled_delay_ms: 1}}
-    ])
-
-    :application.start(:opentelemetry)
-
-    :otel_batch_processor.set_exporter(:otel_exporter_pid, self())
 
     OpenTelemetry.Tracer.start_span("test")
 

instrumentation/opentelemetry_phoenix/config/test.exs

@@ -1,4 +1,4 @@
 import Config
 
 config :opentelemetry,
-  processors: [{:otel_batch_processor, %{scheduled_delay_ms: 1}}]
+  processors: [{:otel_simple_processor, %{}}]

instrumentation/opentelemetry_phoenix/test/opentelemetry_phoenix_test.exs

@@ -17,16 +17,8 @@ defmodule OpentelemetryPhoenixTest do
   end
 
   setup do
-    :application.stop(:opentelemetry)
+    :otel_simple_processor.set_exporter(:otel_exporter_pid, self())
-    :application.set_env(:opentelemetry, :tracer, :otel_tracer_default)
 
-    :application.set_env(:opentelemetry, :processors, [
-      {:otel_batch_processor, %{scheduled_delay_ms: 1}}
-    ])
-
-    :application.start(:opentelemetry)
-
-    :otel_batch_processor.set_exporter(:otel_exporter_pid, self())
     :ok
   end