Fix warn log test.

gems.rb

@@ -21,8 +21,6 @@
 	gem "decode"
 	gem "rubocop"
 
-	gem "sus-fixtures-console"
-
 	gem "bake-test"
 	gem "bake-test-external"
 end

lib/metrics/config.rb

@@ -36,7 +36,7 @@ def require_backend(env = ENV)
 			if backend = env["METRICS_BACKEND"]
 				begin
 					if require(backend)
-						Metrics.extend(Backend::Interface)
+						Metrics.singleton_class.prepend(Backend::Interface)
 
 						return true
 					end

test/metrics/config.rb

@@ -6,22 +6,16 @@
 require "metrics/config"
 require "json"
 
-require "sus/fixtures/console"
-
 describe Metrics::Config do
 	let(:config) {subject.default}
 
 	with ".require_backend" do
-		include_context Sus::Fixtures::Console::CapturedLogger
-
 		it "logs a warning if backend cannot be loaded" do
+			expect(config).to receive(:warn).and_return(nil)
+
 			expect(
 				config.require_backend({"METRICS_BACKEND" => "metrics/backend/missing"})
 			).to be == false
-
-			expect_console.to have_logged(
-				severity: be == :warn,
-			)
 		end
 	end
 end