Improve Hanami integration testing

Improve testing for the Hanami integration by making sure the it
prepends the module in every scenario. That means we're not really
prepending the module to Hanami::Action in the tests, because that would
make testing it multiple times impossible. It's not possible to
"unprepend" a module.

I've updated the prepended module test to prepend the module to an
Action class. First it subclasses the Hanami Action fixture using an
anonymous class (using `Class.new`). Then it prepends the module to that
anonymous class to see if the behavior works.

lib/appsignal/integrations/hanami.rb

@@ -43,4 +43,4 @@ def call(env)
   end
 end
 
-Appsignal::Integrations::HanamiPlugin.init
+Appsignal::Integrations::HanamiPlugin.init unless Appsignal.testing?

spec/lib/appsignal/integrations/hanami_spec.rb

@@ -5,7 +5,12 @@
     require "appsignal/integrations/hanami"
 
     before do
+      Appsignal.config = nil
+      allow(::Hanami::Action).to receive(:prepend)
       uninstall_hanami_middleware
+      ENV["APPSIGNAL_APP_NAME"] = "hanamia-test-app"
+      ENV["APPSIGNAL_APP_ENV"] = "test"
+      ENV["APPSIGNAL_PUSH_API_KEY"] = "0000"
     end
 
     def uninstall_hanami_middleware
@@ -18,19 +23,21 @@ def uninstall_hanami_middleware
 
     describe Appsignal::Integrations::HanamiPlugin do
       it "starts AppSignal on init" do
-        expect(Appsignal).to receive(:start)
+        expect(Appsignal.active?).to be_falsey
+
         Appsignal::Integrations::HanamiPlugin.init
+
+        expect(Appsignal.active?).to be_truthy
       end
 
       it "prepends the integration to Hanami::Action" do
-        allow(Appsignal).to receive(:active?).and_return(true)
         Appsignal::Integrations::HanamiPlugin.init
-        expect(::Hanami::Action.included_modules)
-          .to include(Appsignal::Integrations::HanamiIntegration)
+
+        expect(::Hanami::Action)
+          .to have_received(:prepend).with(Appsignal::Integrations::HanamiIntegration)
       end
 
       it "adds middleware to the Hanami app" do
-        allow(Appsignal).to receive(:active?).and_return(true)
         Appsignal::Integrations::HanamiPlugin.init
 
         expect(::Hanami.app.config.middleware.stack[::Hanami::Router::DEFAULT_PREFIX])
@@ -41,11 +48,16 @@ def uninstall_hanami_middleware
       end
 
       context "when not active" do
-        before { allow(Appsignal).to receive(:active?).and_return(false) }
+        before do
+          ENV.delete("APPSIGNAL_APP_NAME")
+          ENV.delete("APPSIGNAL_APP_ENV")
+          ENV.delete("APPSIGNAL_PUSH_API_KEY")
+        end
 
         it "does not prepend the integration to Hanami::Action" do
           Appsignal::Integrations::HanamiPlugin.init
-          expect(::Hanami::Action).to_not receive(:prepend)
+
+          expect(::Hanami::Action).to_not have_received(:prepend)
             .with(Appsignal::Integrations::HanamiIntegration)
         end
 
@@ -85,14 +97,24 @@ def uninstall_hanami_middleware
 
     describe Appsignal::Integrations::HanamiIntegration do
       let(:transaction) { http_request_transaction }
+      let(:app) do
+        Class.new(HanamiApp::Actions::Books::Index) do
+          def self.name
+            "HanamiApp::Actions::Books::Index::TestClass"
+          end
+        end
+      end
       around { |example| keep_transactions { example.run } }
-      before(:context) { start_agent }
       before do
-        allow(Appsignal).to receive(:active?).and_return(true)
+        ENV["APPSIGNAL_APP_NAME"] = "hanamia-test-app"
+        ENV["APPSIGNAL_APP_ENV"] = "test"
+        ENV["APPSIGNAL_PUSH_API_KEY"] = "0000"
         Appsignal::Integrations::HanamiPlugin.init
+        allow(app).to receive(:prepend).and_call_original
+        app.prepend(Appsignal::Integrations::HanamiIntegration)
       end
 
-      def make_request(env, app: HanamiApp::Actions::Books::Index)
+      def make_request(env)
         action = app.new
         action.call(env)
       end
@@ -117,7 +139,7 @@ def make_request(env, app: HanamiApp::Actions::Books::Index)
             make_request(env)
 
             expect(transaction.to_h).to include(
-              "action" => "HanamiApp::Actions::Books::Index"
+              "action" => "HanamiApp::Actions::Books::Index::TestClass"
             )
           end
         end