Move footprint to db folder

lib/sql_footprint/sql_capturer.rb

@@ -27,7 +27,7 @@ def serialized_statements
     end
 
     def filename
-      "footprint.#{database_name.split('/').last}.sql"
+      "db/footprint.#{database_name.split('/').last}.sql"
     end
   end
 end

spec/sql_footprint/sql_capturer_spec.rb

@@ -79,7 +79,7 @@
     end
 
     it 'writes to db-specific filename' do
-      expect(File).to receive(:write).with("footprint.#{db_name}.sql", anything)
+      expect(File).to receive(:write).with("db/footprint.#{db_name}.sql", anything)
       subject.write
     end
   end

spec/sql_footprint_spec.rb

@@ -6,7 +6,7 @@
   end
 
   let(:statements) { described_class.capturers[':memory:'].statements }
-  let(:footprint_file_name) { 'footprint.:memory:.sql' }
+  let(:footprint_file_name) { './db/footprint.:memory:.sql' }
 
   describe '.start' do
     before do