Rename pg_stat_wal_receiver_supported? DB helper

From pg_stat_wal_receiver_supported? to
postgresql_minimum_supported_version?

Also add test coverage

ee/app/controllers/admin/geo/nodes_controller.rb

@@ -15,7 +15,7 @@ class Admin::Geo::NodesController < Admin::ApplicationController
       flash.now[:alert] = _('You need a different license to enable Geo replication.')
     end
 
-    unless Gitlab::Database.pg_stat_wal_receiver_supported?
+    unless Gitlab::Database.postgresql_minimum_supported_version?
       flash.now[:warning] = _('Please upgrade PostgreSQL to version 9.6 or greater. The status of the replication cannot be determined reliably with the current version.')
     end
   end

ee/lib/tasks/geo.rake

@@ -220,7 +220,7 @@ namespace :geo do
     puts GeoNode.current_node_url
     puts '-----------------------------------------------------'.color(:yellow)
 
-    unless Gitlab::Database.pg_stat_wal_receiver_supported?
+    unless Gitlab::Database.postgresql_minimum_supported_version?
       puts
       puts 'WARNING: Please upgrade PostgreSQL to version 9.6 or greater. The status of the replication cannot be determined reliably with the current version.'.color(:red)
       puts

ee/spec/controllers/admin/geo/nodes_controller_spec.rb

@@ -65,7 +65,7 @@ describe Admin::Geo::NodesController, :postgresql do
 
     context 'with Postgres 9.6 or greater' do
       before do
-        allow(Gitlab::Database).to receive(:pg_stat_wal_receiver_supported?).and_return(true)
+        allow(Gitlab::Database).to receive(:postgresql_minimum_supported_version?).and_return(true)
       end
 
       it_behaves_like 'no flash message', :warning
@@ -73,7 +73,7 @@ describe Admin::Geo::NodesController, :postgresql do
 
     context 'without Postgres 9.6 or greater' do
       before do
-        allow(Gitlab::Database).to receive(:pg_stat_wal_receiver_supported?).and_return(false)
+        allow(Gitlab::Database).to receive(:postgresql_minimum_supported_version?).and_return(false)
       end
 
       it_behaves_like 'with flash message', :warning, 'Please upgrade PostgreSQL to version 9.6 or greater.'

lib/gitlab/database.rb

@@ -80,7 +80,7 @@ module Gitlab
       postgresql? && version.to_f >= 9.4
     end
 
-    def self.pg_stat_wal_receiver_supported?
+    def self.postgresql_minimum_supported_version?
       postgresql? && version.to_f >= 9.6
     end
 

spec/lib/gitlab/database_spec.rb

@@ -87,6 +87,38 @@ describe Gitlab::Database do
     end
   end
 
+  describe '.postgresql_minimum_supported_version?' do
+    it 'returns false when not using PostgreSQL' do
+      allow(described_class).to receive(:postgresql?).and_return(false)
+
+      expect(described_class.postgresql_minimum_supported_version?).to eq(false)
+    end
+
+    context 'when using PostgreSQL' do
+      before do
+        allow(described_class).to receive(:postgresql?).and_return(true)
+      end
+
+      it 'returns false when using PostgreSQL 9.5' do
+        allow(described_class).to receive(:version).and_return('9.5')
+
+        expect(described_class.postgresql_minimum_supported_version?).to eq(false)
+      end
+
+      it 'returns true when using PostgreSQL 9.6' do
+        allow(described_class).to receive(:version).and_return('9.6')
+
+        expect(described_class.postgresql_minimum_supported_version?).to eq(true)
+      end
+
+      it 'returns true when using PostgreSQL 10 or newer' do
+        allow(described_class).to receive(:version).and_return('10')
+
+        expect(described_class.postgresql_minimum_supported_version?).to eq(true)
+      end
+    end
+  end
+
   describe '.join_lateral_supported?' do
     it 'returns false when using MySQL' do
       allow(described_class).to receive(:postgresql?).and_return(false)