Streamline configuration of account/admin hosts

There is one reasonable default for the tenant domain template, if only
the admin_host is configured, namely `"%{tenant}.#{admin_host}"`.
Adding one piece of logic in code means we no longer have to specify a
base in `settings.yml` only to override it.  This flexibility will be
useful when we try to standardize development with multitenancy enabled.

This is backwards compatible and all previous configs will still work.

app/models/account.rb

@@ -5,10 +5,19 @@ class Account < ActiveRecord::Base
   # @see Settings.multitenancy.default_host
   def self.default_cname(piece)
     return unless piece
-    default_host = Settings.multitenancy.default_host
+    default_host = Settings.multitenancy.default_host || "%{tenant}.#{admin_host}"
     format(default_host, tenant: piece.parameterize)
   end
 
+  # Canonicalize the account cname or request host for comparison
+  # @param [String] cname distinct part of host name
+  # @return [String] canonicalized host name
+  def self.canonical_cname(cname)
+    # DNS host names are case-insensitive. Convert complete domain names to relative names.
+    cname &&= cname.downcase.sub(/\.\Z/, '')
+    cname
+  end
+
   def self.admin_host
     host = Settings.multitenancy.admin_host
     host ||= ENV['HOST']
@@ -49,16 +58,6 @@ def self.single_tenant_default
     end
   end
 
-  # Canonicalize the account cname or request host for comparison
-  #
-  # @param [String] cname distinct part of host name
-  # @return [String] canonicalized host name
-  def self.canonical_cname(cname)
-    # DNS host names are case-insensitive. Convert complete domain names to relative names.
-    cname &&= cname.downcase.sub(/\.\Z/, '')
-    cname
-  end
-
   # Make all the account specific connections active
   def switch!
     solr_endpoint.switch! if solr_endpoint

config/settings.yml

@@ -5,7 +5,7 @@
 #
 multitenancy:
   enabled: false
-  default_host: "%{tenant}.dev"
+  default_host: # "%{tenant}.dev"
   admin_host:
 
 ssl_configured: false

config/settings/test.yml

@@ -3,3 +3,5 @@ zookeeper:
 
 multitenancy:
   enabled: false
+# admin_host: 'localhost'
+# default_host: "%{tenant}.localhost"

spec/controllers/account_sign_up_controller_spec.rb

@@ -35,7 +35,7 @@
           expect do
             post :create, params: { account: valid_attributes }
           end.to change(Account, :count).by(1)
-          expect(assigns(:account).cname).to eq('x.dev')
+          expect(assigns(:account).cname).to eq('x.localhost')
           expect(assigns(:account).errors).to be_empty
 
           expect do # now repeat the same action

spec/models/account_spec.rb

@@ -119,19 +119,49 @@
       expect(account1.errors).to be_empty
     end
 
-    it 'builds default cname from name' do
-      account1 = described_class.create(tenant: 'example', name: 'example')
-      expect(account1.errors).to be_empty
-      expect(account1.cname).to eq('example.dev')
+    context 'default_host' do
+      let(:account1) { described_class.create(tenant: 'example', name: 'example') }
+
+      context 'is set' do
+        it 'builds default cname from name and default_host' do
+          allow(Settings.multitenancy).to receive(:default_host).and_return "%{tenant}.dev"
+          expect(account1.errors).to be_empty
+          expect(account1.cname).to eq('example.dev')
+        end
+      end
+
+      context 'is unset' do
+        it 'builds default cname from name and admin_host' do
+          allow(Settings.multitenancy).to receive(:admin_host).and_return('admin-host')
+          expect(account1.errors).to be_empty
+          expect(account1.cname).to eq('example.admin-host')
+        end
+      end
     end
 
     it 'prevents duplicate cname and tenant values' do
-      account1 = described_class.create(name: 'example', tenant: 'example', cname: 'example.dev')
-      account2 = described_class.create(name: 'example', tenant: 'example', cname: 'example.dev')
+      account1 = described_class.create(name: 'example', tenant: 'example_tenant', cname: 'example.dev')
+      account2 = described_class.create(name: 'example', tenant: 'example_tenant', cname: 'example.dev')
       expect(account1.errors).to be_empty
       expect(account2.errors).not_to be_empty
       expect(account2.errors.messages).to match a_hash_including(:tenant, :cname)
       expect(account2.errors.messages).not_to include(:name)
     end
+
+    it 'prevents duplicate cname from only name' do
+      account1 = described_class.create(name: 'example')
+      account2 = described_class.create(name: 'example')
+      expect(account1.errors).to be_empty
+      expect(account2.errors).not_to be_empty
+      expect(account2.errors.messages).to match a_hash_including(:cname)
+      expect(account2.errors.messages).not_to include(:name)
+    end
+
+    it 'prevents conflicting new object saves' do
+      described_class.create(name: 'example', title: 'Original Example')
+      account2 = described_class.new(name: 'example', title: 'Fancy Example')
+      expect(account2.save).to be false
+      expect(account2.errors).to match a_hash_including(:cname)
+    end
   end
 end