tests: fix post and pool version tests helpers.

* Fix the pool version SQS service to always be mocked before every
  test. Before we had to manually set it up before every test dealing
  with pool versions.

* Fix it so that we reconnect to the post/pool version databases before
  every test. Before using $ARCHIVE_DATABASE_URL to set the database url
  failed because environment variables weren't loaded by dotenv yet when
  connections were first established.

test/test_helpers/pool_archive_test_helper.rb

@@ -1,30 +1,30 @@
 module PoolArchiveTestHelper
-  def mock_pool_archive_service!
-    mock_sqs_service = Class.new do
-      def send_message(msg, *options)
-        _, json = msg.split(/\n/)
-        json = JSON.parse(json)
-        prev = PoolVersion.where(pool_id: json["pool_id"]).order("id desc").first
-        if merge?(prev, json)
-          prev.update_columns(json)
-        else
-          PoolVersion.create(json)
-        end
-      end
+  def mock_pool_version_service!
+    setup do
+      PoolVersion.stubs(:sqs_service).returns(MockPoolSqsService.new)
+      PoolVersion.establish_connection(PoolVersion.database_url)
+      PoolVersion.connection.begin_transaction joinable: false
+    end
 
-      def merge?(prev, json)
-        prev && (prev.updater_id == json["updater_id"]) && (prev.updated_at >= 1.hour.ago)
+    teardown do
+      PoolVersion.connection.rollback_transaction
+    end
+  end
+
+  class MockPoolSqsService
+    def send_message(msg, *options)
+      _, json = msg.split(/\n/)
+      json = JSON.parse(json)
+      prev = PoolVersion.where(pool_id: json["pool_id"]).order("id desc").first
+      if merge?(prev, json)
+        prev.update_columns(json)
+      else
+        PoolVersion.create!(json)
       end
     end
 
-    PoolVersion.stubs(:sqs_service).returns(mock_sqs_service.new)
-  end
-
-  def start_pool_archive_transaction
-    PoolVersion.connection.begin_transaction joinable: false
-  end
-
-  def rollback_pool_archive_transaction
-    PoolVersion.connection.rollback_transaction
+    def merge?(prev, json)
+      prev && (prev.updater_id == json["updater_id"]) && (prev.updated_at >= 1.hour.ago)
+    end
   end
 end