Allowing to exclude subdomains by a regular expression

lib/apartment/elevators/subdomain.rb

@@ -14,12 +14,22 @@ def self.excluded_subdomains=(arg)
         @excluded_subdomains = arg
       end
 
+      def self.excluded_subdomain?(subdomain)
+        excluded_subdomains.any? do |excluded_subdomain|
+          if excluded_subdomain.is_a? Regexp
+            subdomain =~ excluded_subdomain
+          else
+            subdomain == excluded_subdomain
+          end
+        end
+      end
+
       def parse_tenant_name(request)
         request_subdomain = subdomain(request.host)
 
         # If the domain acquired is set to be excluded, set the tenant to whatever is currently
         # next in line in the schema search path.
-        tenant = if self.class.excluded_subdomains.include?(request_subdomain)
+        tenant = if self.class.excluded_subdomain?(request_subdomain)
           nil
         else
           request_subdomain

spec/unit/elevators/subdomain_spec.rb

@@ -53,4 +53,28 @@
       described_class.excluded_subdomains = nil
     end
   end
+
+  describe ".excluded_subdomain?" do
+    it "must ignore any item of the list" do
+      described_class.excluded_subdomains = %w{foo bar cereal}
+
+      expect(described_class.excluded_subdomain?("foo")).to eq(true)
+      expect(described_class.excluded_subdomain?("bar")).to eq(true)
+      expect(described_class.excluded_subdomain?("cereal")).to eq(true)
+      expect(described_class.excluded_subdomain?("flakes")).to eq(false)
+
+      described_class.excluded_subdomains = nil
+    end
+
+    it "must ignore regexp's on the list that match" do
+      described_class.excluded_subdomains = [/foo/, /bar/, /cereal-\d+/]
+
+      expect(described_class.excluded_subdomain?("food")).to eq(true)
+      expect(described_class.excluded_subdomain?("bareatric")).to eq(true)
+      expect(described_class.excluded_subdomain?("cereal")).to eq(false)
+      expect(described_class.excluded_subdomain?("cereal-1985")).to eq(true)
+
+      described_class.excluded_subdomains = nil
+    end
+  end
 end