Account search service refactor (#1791)

* Begin coverage for account search service

* Coverage for hashtag query

* Coverage for calling local vs remote find based on domain presence

* Spec to check that exact matches are not duped

* Coverage of resolve option

* Coverage for account being provided

* Start to refactor account search service

* Isolate query username and domain methods

* Isolate exact_match method

* Extract methods for local and remote results

* Simplify local vs remote and account isoliation

* Extract methods for local and remote results

* Simplify de-dupe of exact match

* Simplify logic to check for non exact remotes

* Cache some methods

* Remove nil from exact_match from results array

* Return exact matches first

* Use find_remote even with no domain

Account.find_local is just an alias for Account.find_remote(user, nil) - so we
can not bother with the conditional here, and call find_remote directly.

spec/services/account_search_service_spec.rb

@@ -0,0 +1,104 @@
+require 'rails_helper'
+
+describe AccountSearchService do
+  describe '.call' do
+    describe 'with a query to ignore' do
+      it 'returns empty array for missing query' do
+        results = subject.call('', 10)
+
+        expect(results).to eq []
+      end
+      it 'returns empty array for hashtag query' do
+        results = subject.call('#tag', 10)
+
+        expect(results).to eq []
+      end
+    end
+
+    describe 'searching for a simple term that is not an exact match' do
+      it 'does not return a nil entry in the array for the exact match' do
+        match = Fabricate(:account, username: 'matchingusername')
+
+        results = subject.call('match', 5)
+        expect(results).to eq [match]
+      end
+    end
+
+    describe 'searching local and remote users' do
+      describe 'when no domain' do
+        before do
+          allow(Account).to receive(:find_remote)
+          allow(Account).to receive(:search_for)
+          subject.call('one', 10)
+        end
+
+        it 'uses find_remote with nil domain to look for local accounts' do
+          expect(Account).to have_received(:find_remote).with('one', nil)
+        end
+
+        it 'uses search_for to find matches' do
+          expect(Account).to have_received(:search_for).with('one', 10)
+        end
+      end
+
+      describe 'when there is a domain' do
+        before do
+          allow(Account).to receive(:find_remote)
+        end
+
+        it 'uses find_remote to look for remote accounts' do
+          subject.call('two@example.com', 10)
+          expect(Account).to have_received(:find_remote).with('two', 'example.com')
+        end
+
+        describe 'and there is no account provided' do
+          it 'uses search_for to find matches' do
+            allow(Account).to receive(:search_for)
+            subject.call('two@example.com', 10, false, nil)
+
+            expect(Account).to have_received(:search_for).with('two example.com', 10)
+          end
+        end
+
+        describe 'and there is an account provided' do
+          it 'uses advanced_search_for to find matches' do
+            account = Fabricate(:account)
+            allow(Account).to receive(:advanced_search_for)
+            subject.call('two@example.com', 10, false, account)
+
+            expect(Account).to have_received(:advanced_search_for).with('two example.com', account, 10)
+          end
+        end
+      end
+    end
+
+    describe 'with an exact match' do
+      it 'returns exact match first, and does not return duplicates' do
+        partial = Fabricate(:account, username: 'exactness')
+        exact = Fabricate(:account, username: 'exact')
+
+        results = subject.call('exact', 10)
+        expect(results.size).to eq 2
+        expect(results).to eq [exact, partial]
+      end
+    end
+
+    describe 'when there is a domain but no exact match' do
+      it 'follows the remote account when resolve is true' do
+        service = double(call: nil)
+        allow(FollowRemoteAccountService).to receive(:new).and_return(service)
+
+        results = subject.call('newuser@remote.com', 10, true)
+        expect(service).to have_received(:call).with('newuser@remote.com')
+      end
+
+      it 'does not follow the remote account when resolve is false' do
+        service = double(call: nil)
+        allow(FollowRemoteAccountService).to receive(:new).and_return(service)
+
+        results = subject.call('newuser@remote.com', 10, false)
+        expect(service).not_to have_received(:call)
+      end
+    end
+  end
+end