Change domain blocks to automatically support subdomains (#11138)

* Change domain blocks to automatically support subdomains

If a more authoritative domain is blocked (example.com), then the
same block will be applied to a subdomain (foo.example.com)

* Match subdomains of existing accounts when blocking/unblocking domains

* Improve code style

spec/models/account_spec.rb

@@ -687,6 +687,23 @@ RSpec.describe Account, type: :model do
       end
     end
 
+    describe 'by_domain_and_subdomains' do
+      it 'returns exact domain matches' do
+        account = Fabricate(:account, domain: 'example.com')
+        expect(Account.by_domain_and_subdomains('example.com')).to eq [account]
+      end
+
+      it 'returns subdomains' do
+        account = Fabricate(:account, domain: 'foo.example.com')
+        expect(Account.by_domain_and_subdomains('example.com')).to eq [account]
+      end
+
+      it 'does not return partially matching domains' do
+        account = Fabricate(:account, domain: 'grexample.com')
+        expect(Account.by_domain_and_subdomains('example.com')).to_not eq [account]
+      end
+    end
+
     describe 'expiring' do
       it 'returns remote accounts with followers whose subscription expiration date is past or not given' do
         local = Fabricate(:account, domain: nil)

spec/models/domain_block_spec.rb

@@ -21,23 +21,40 @@ RSpec.describe DomainBlock, type: :model do
     end
   end
 
-  describe 'blocked?' do
+  describe '.blocked?' do
     it 'returns true if the domain is suspended' do
-      Fabricate(:domain_block, domain: 'domain', severity: :suspend)
-      expect(DomainBlock.blocked?('domain')).to eq true
+      Fabricate(:domain_block, domain: 'example.com', severity: :suspend)
+      expect(DomainBlock.blocked?('example.com')).to eq true
     end
 
     it 'returns false even if the domain is silenced' do
-      Fabricate(:domain_block, domain: 'domain', severity: :silence)
-      expect(DomainBlock.blocked?('domain')).to eq false
+      Fabricate(:domain_block, domain: 'example.com', severity: :silence)
+      expect(DomainBlock.blocked?('example.com')).to eq false
     end
 
     it 'returns false if the domain is not suspended nor silenced' do
-      expect(DomainBlock.blocked?('domain')).to eq false
+      expect(DomainBlock.blocked?('example.com')).to eq false
     end
   end
 
-  describe 'stricter_than?' do
+  describe '.rule_for' do
+    it 'returns rule matching a blocked domain' do
+      block = Fabricate(:domain_block, domain: 'example.com')
+      expect(DomainBlock.rule_for('example.com')).to eq block
+    end
+
+    it 'returns a rule matching a subdomain of a blocked domain' do
+      block = Fabricate(:domain_block, domain: 'example.com')
+      expect(DomainBlock.rule_for('sub.example.com')).to eq block
+    end
+
+    it 'returns a rule matching a blocked subdomain' do
+      block = Fabricate(:domain_block, domain: 'sub.example.com')
+      expect(DomainBlock.rule_for('sub.example.com')).to eq block
+    end
+  end
+
+  describe '#stricter_than?' do
     it 'returns true if the new block has suspend severity while the old has lower severity' do
       suspend = DomainBlock.new(domain: 'domain', severity: :suspend)
       silence = DomainBlock.new(domain: 'domain', severity: :silence)