Change e-mail domain blocks to match subdomains of blocked domains (#18979)

spec/models/email_domain_block_spec.rb

@@ -12,16 +12,29 @@ RSpec.describe EmailDomainBlock, type: :model do
     let(:input) { nil }
 
     context 'given an e-mail address' do
-      let(:input) { 'nyarn@example.com' }
+      let(:input) { "foo@#{domain}" }
 
-      it 'returns true if the domain is blocked' do
-        Fabricate(:email_domain_block, domain: 'example.com')
-        expect(EmailDomainBlock.block?(input)).to be true
+      context do
+        let(:domain) { 'example.com' }
+
+        it 'returns true if the domain is blocked' do
+          Fabricate(:email_domain_block, domain: 'example.com')
+          expect(EmailDomainBlock.block?(input)).to be true
+        end
+
+        it 'returns false if the domain is not blocked' do
+          Fabricate(:email_domain_block, domain: 'other-example.com')
+          expect(EmailDomainBlock.block?(input)).to be false
+        end
       end
 
-      it 'returns false if the domain is not blocked' do
-        Fabricate(:email_domain_block, domain: 'other-example.com')
-        expect(EmailDomainBlock.block?(input)).to be false
+      context do
+        let(:domain) { 'mail.example.com' }
+
+        it 'returns true if it is a subdomain of a blocked domain' do
+          Fabricate(:email_domain_block, domain: 'example.com')
+          expect(described_class.block?(input)).to be true
+        end
       end
     end