From 0aa9f6f5e9a48f0bff21816fd225a79f82917018 Mon Sep 17 00:00:00 2001
From: Bruce Bolt <bruce.bolt@digital.cabinet-office.gov.uk>
Date: Mon, 30 Sep 2024 15:59:05 +0100
Subject: [PATCH] Use only `EMERGENCY_BANNER_REDIS_URL` environment variable

In 9683ede220f184f188ff4b86e68461b2f09b2872, we allowed this application
to use either `EMERGENCY_BANNER_REDIS_URL` or `REDIS_URL`, as different
environments were in differet states.

That is no longer the case, so we can remove the code to default to one
over the other.
---
 lib/emergency_banner/display.rb            |  2 +-
 test/unit/emergency_banner/display_test.rb | 55 ----------------------
 2 files changed, 1 insertion(+), 56 deletions(-)

diff --git a/lib/emergency_banner/display.rb b/lib/emergency_banner/display.rb
index de9171f9d..b99dab2b0 100644
--- a/lib/emergency_banner/display.rb
+++ b/lib/emergency_banner/display.rb
@@ -3,7 +3,7 @@ class Display
     class << self
       def client
         @client ||= Redis.new(
-          url: ENV.fetch("EMERGENCY_BANNER_REDIS_URL", ENV["REDIS_URL"]),
+          url: ENV["EMERGENCY_BANNER_REDIS_URL"],
           reconnect_attempts: [
             15,
             30,
diff --git a/test/unit/emergency_banner/display_test.rb b/test/unit/emergency_banner/display_test.rb
index 70fb108a9..f6a6bf24e 100644
--- a/test/unit/emergency_banner/display_test.rb
+++ b/test/unit/emergency_banner/display_test.rb
@@ -7,51 +7,6 @@
     @banner = EmergencyBanner::Display.new
   end
 
-  context ".client" do
-    context "when the EMERGENCY_BANNER_REDIS_URL environment variable has been set" do
-      should "use that value as the URL for the Redis client" do
-        mock_env("EMERGENCY_BANNER_REDIS_URL" => "redis://emergency-banner") do
-          EmergencyBanner::Display.instance_variable_set(:@client, nil)
-
-          Redis.expects(:new).with(
-            url: "redis://emergency-banner",
-            reconnect_attempts: [
-              15,
-              30,
-              45,
-              60,
-            ],
-          )
-
-          EmergencyBanner::Display.client
-        end
-      end
-    end
-
-    context "when the EMERGENCY_BANNER_REDIS_URL environment variable has not been set" do
-      should "use the default REDIS_URL as the URL for the Redis client" do
-        mock_env({
-          "EMERGENCY_BANNER_REDIS_URL" => nil,
-          "REDIS_URL" => "redis://my-redis-url",
-        }) do
-          EmergencyBanner::Display.instance_variable_set(:@client, nil)
-
-          Redis.expects(:new).with(
-            url: "redis://my-redis-url",
-            reconnect_attempts: [
-              15,
-              30,
-              45,
-              60,
-            ],
-          )
-
-          EmergencyBanner::Display.client
-        end
-      end
-    end
-  end
-
   context "#enabled?" do
     should "return enabled is false when redis connection times out and send an error notification" do
       err = Redis::CannotConnectError.new("Timed out connecting to Redis")
@@ -200,15 +155,5 @@
       assert_nil @banner.link_text
     end
   end
-
-  def mock_env(partial_env_hash)
-    old_env = ENV.to_hash
-    ENV.update partial_env_hash
-    begin
-      yield
-    ensure
-      ENV.replace old_env
-    end
-  end
 end
 # rubocop:enable Rails/RefuteMethods