Created
June 3, 2015 21:37
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RSpec Query Limit matcher
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| # Allows for assertions regarding number of queries executed. | |
| # | |
| # Usage: | |
| # it "eager loads `#manager` association" do | |
| # expect do | |
| # employee = Employee.with_manager.find(employee_id) | |
| # employee.manager | |
| # end.to satisfy_query_limit(1) | |
| # end | |
| RSpec::Matchers.define :satisfy_query_limit do |expected| | |
| match do |block| | |
| count_queries(&block) <= expected | |
| end | |
| failure_message_for_should do |actual| | |
| "Expected to execute no more than #{expected} SQL queries, got #{@query_count}" | |
| end | |
| failure_message_for_should_not do |actual| | |
| "Expected to execute more than #{expected} SQL queries, got #{@query_count}" | |
| end | |
| def count_queries | |
| @query_count = 0 | |
| filter_list = %w[CACHE SCHEMA] | |
| # Rails 3.2 introduces ActiveSupport::Notifications::subscribed for temporary | |
| # subscribers. Use that for 3.2+ | |
| query_counter = ->(name, started, finished, unique_id, payload) do | |
| @query_count += 1 unless payload[:name].in?(filter_list) | |
| end | |
| subscriber = ActiveSupport::Notifications.subscribe("sql.active_record", query_counter) | |
| yield | |
| ActiveSupport::Notifications.unsubscribe(subscriber) | |
| @query_count | |
| end | |
| end |
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