Replace active_sentry_environments with enabled_environments

The custom option `active_sentry_environments` was added in
#168.

However, it turns out there is already a native option for this:
`enabled_environments`. See
https://docs.sentry.io/platforms/ruby/configuration/options/

This allows us to simplify our code a fair bit.

I've also removed the stubbed `sending_allowed?` method as it was
interfering with some tests and giving a false sense of security.
We're now providing all of the necessary configuration for
the `Sentry::Configuration` instance to return `true` on its
`valid?` method, so no need for the hack.
Each config option is documented in an inline comment as otherwise
it can be quite obtuse.

README.md

@@ -87,7 +87,7 @@ You can add your environment to the list of active Sentry environments like so:
 
 ```ruby
 GovukError.configure do |config|
-  config.active_sentry_environments << "my-test-environment"
+  config.enabled_environments << "my-test-environment"
 end
 ```
 

lib/govuk_app_config/govuk_error/configuration.rb

@@ -3,17 +3,14 @@
 
 module GovukError
   class Configuration < SimpleDelegator
-    attr_reader :data_sync, :sentry_environment
-    attr_accessor :active_sentry_environments, :data_sync_excluded_exceptions
+    attr_reader :data_sync
+    attr_accessor :data_sync_excluded_exceptions
 
     def initialize(_sentry_configuration)
       super
-      @sentry_environment = ENV["SENTRY_CURRENT_ENV"]
       @data_sync = GovukDataSync.new(ENV["GOVUK_DATA_SYNC_PERIOD"])
-      self.active_sentry_environments = []
       self.data_sync_excluded_exceptions = []
       @before_send_callbacks = [
-        ignore_exceptions_if_not_in_active_sentry_env,
         ignore_excluded_exceptions_in_data_sync,
         increment_govuk_statsd_counters,
       ]
@@ -26,10 +23,6 @@ def before_send=(closure)
 
   protected
 
-    def ignore_exceptions_if_not_in_active_sentry_env
-      ->(event, _hint) { event if active_sentry_environments.include?(sentry_environment) }
-    end
-
     def ignore_excluded_exceptions_in_data_sync
       lambda { |event, hint|
         data_sync_ignored_error = data_sync_excluded_exceptions.any? do |exception_to_ignore|

lib/govuk_app_config/govuk_error/configure.rb

@@ -3,7 +3,7 @@
   # ENV variable) where we want to capture Sentry errors. If
   # `SENTRY_CURRENT_ENV` isn't in this list, or isn't defined, then
   # don't capture the error.
-  config.active_sentry_environments = %w[
+  config.enabled_environments = %w[
     integration-blue-aws
     staging
     production

spec/govuk_error/configuration_spec.rb

@@ -3,8 +3,12 @@
 require "govuk_app_config/govuk_error/configuration"
 
 RSpec.describe GovukError::Configuration do
+  let(:dummy_dsn) { "http://12345:67890@sentry.localdomain/sentry/42" }
+
   before :each do
     stub_const("GovukStatsd", double(Module, increment: nil))
+    stub_request(:post, "http://sentry.localdomain/sentry/api/42/envelope/")
+      .to_return(status: 200, body: "", headers: {})
   end
 
   describe ".initialize" do
@@ -26,23 +30,23 @@
 
     it "ignores errors if they happen in an environment we don't care about" do
       ClimateControl.modify SENTRY_CURRENT_ENV: "some-temporary-environment" do
-        configuration.active_sentry_environments << "production"
+        configuration.enabled_environments << "production"
         sentry_client = send_exception_to_sentry(StandardError.new, configuration)
         expect(sentry_client.transport.events).to be_empty
       end
     end
 
     it "captures errors if they happen in an environment we care about" do
       ClimateControl.modify SENTRY_CURRENT_ENV: "production" do
-        configuration.active_sentry_environments << "production"
+        configuration.enabled_environments << "production"
         sentry_client = send_exception_to_sentry(StandardError.new, configuration)
         expect(sentry_client.transport.events.count).to eq(1)
       end
     end
 
     it "allows string messages to be sent (rather than exceptions)" do
       ClimateControl.modify SENTRY_CURRENT_ENV: "production" do
-        configuration.active_sentry_environments << "production"
+        configuration.enabled_environments << "production"
         configuration.data_sync_excluded_exceptions << "SomeError"
         sentry_client = Sentry::Client.new(optimise_configuration_for_testing(configuration))
         sentry_hub = Sentry::Hub.new(sentry_client, Sentry::Scope.new)
@@ -55,7 +59,7 @@
     context "during the data sync" do
       around do |example|
         ClimateControl.modify SENTRY_CURRENT_ENV: "production", GOVUK_DATA_SYNC_PERIOD: "22:00-08:00" do
-          configuration.active_sentry_environments << "production"
+          configuration.enabled_environments << "production"
           travel_to(Time.current.change(hour: 23)) do
             example.run
           end
@@ -115,7 +119,7 @@
     context "outside of the data sync" do
       around do |example|
         ClimateControl.modify SENTRY_CURRENT_ENV: "production", GOVUK_DATA_SYNC_PERIOD: "22:00-08:00" do
-          configuration.active_sentry_environments << "production"
+          configuration.enabled_environments << "production"
           travel_to(Time.current.change(hour: 21)) do
             example.run
           end
@@ -133,7 +137,7 @@
     context "when the before_send lambda has not been overridden" do
       it "increments the appropriate counters" do
         ClimateControl.modify SENTRY_CURRENT_ENV: "production" do
-          configuration.active_sentry_environments << "production"
+          configuration.enabled_environments << "production"
           expect(GovukStatsd).to receive(:increment).exactly(1).times.with("errors_occurred")
           expect(GovukStatsd).to receive(:increment).exactly(1).times.with("error_types.standard_error")
           send_exception_to_sentry(StandardError.new, configuration)
@@ -144,7 +148,7 @@
     context "when the before_send lambda has been overridden" do
       it "increments the appropriate counters" do
         ClimateControl.modify SENTRY_CURRENT_ENV: "production" do
-          configuration.active_sentry_environments << "production"
+          configuration.enabled_environments << "production"
           expect(GovukStatsd).to receive(:increment).exactly(1).times.with("errors_occurred")
           expect(GovukStatsd).to receive(:increment).exactly(1).times.with("error_types.standard_error")
           expect(GovukStatsd).to receive(:increment).exactly(1).times.with("hello_world")
@@ -162,7 +166,7 @@
     context "when the before_send lambda has been overridden several times, all take effect" do
       it "increments the appropriate counters" do
         ClimateControl.modify SENTRY_CURRENT_ENV: "production" do
-          configuration.active_sentry_environments << "production"
+          configuration.enabled_environments << "production"
           expect(GovukStatsd).to receive(:increment).exactly(1).times.with("errors_occurred")
           expect(GovukStatsd).to receive(:increment).exactly(1).times.with("error_types.standard_error")
           expect(GovukStatsd).to receive(:increment).exactly(1).times.with("hello_world")
@@ -185,7 +189,7 @@
     context "when a message rather than an exception is sent to Sentry" do
       it "does not increment the error counters" do
         ClimateControl.modify SENTRY_CURRENT_ENV: "production" do
-          configuration.active_sentry_environments << "production"
+          configuration.enabled_environments << "production"
           sentry_client = Sentry::Client.new(optimise_configuration_for_testing(configuration))
           sentry_hub = Sentry::Hub.new(sentry_client, Sentry::Scope.new)
 
@@ -202,7 +206,7 @@
     it "Allows apps to add their own `before_send` callback, that is evaluated alongside the default. If all return their parameter, then the chain continues, but if any returns `nil`, then it ends and the error is dropped" do
       ClimateControl.modify SENTRY_CURRENT_ENV: "production" do
         sentry_configurator = GovukError::Configuration.new(Sentry::Configuration.new)
-        sentry_configurator.active_sentry_environments << "production"
+        sentry_configurator.enabled_environments << "production"
         stub_const("CustomError", Class.new(StandardError))
         sentry_configurator.before_send = lambda do |event, hint|
           event if hint[:exception].is_a?(CustomError)
@@ -218,7 +222,7 @@
     it "does not increment the counters if the callback returns nil" do
       ClimateControl.modify SENTRY_CURRENT_ENV: "production" do
         sentry_configurator = GovukError::Configuration.new(Sentry::Configuration.new)
-        sentry_configurator.active_sentry_environments << "production"
+        sentry_configurator.enabled_environments << "production"
         sentry_configurator.before_send = lambda do |_error_or_event, _hint|
           nil
         end
@@ -241,8 +245,11 @@ def send_exception_to_sentry(event, configuration)
   def optimise_configuration_for_testing(configuration)
     # prevent the sending happening in a separate worker, which would cause async results
     configuration.background_worker_threads = 0
-    # force configuration to allow sending
-    allow(configuration).to receive(:sending_allowed?).and_return(true)
+    # allows us to debug which events have been sent to Sentry
+    # https://github.com/getsentry/sentry-ruby/blob/b9aa6ca8ad2bb1965ca58c7f8fc0dd16b5df310b/sentry-ruby/lib/sentry/transport/dummy_transport.rb#L7-L11
+    configuration.transport.transport_class = Sentry::DummyTransport
+    # required for `Sentry::Configuration`'s `valid?` method to return `true`
+    configuration.dsn = dummy_dsn
     configuration
   end
 end