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https://github.com/nepalez/rspec-sqlimit
RSpec matcher to control SQL queries made by block of code
https://github.com/nepalez/rspec-sqlimit
activerecord rails rspec rspec-matchers ruby ruby-on-rails
Last synced: 5 days ago
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RSpec matcher to control SQL queries made by block of code
- Host: GitHub
- URL: https://github.com/nepalez/rspec-sqlimit
- Owner: nepalez
- License: mit
- Created: 2017-02-12T11:13:06.000Z (almost 8 years ago)
- Default Branch: master
- Last Pushed: 2024-01-26T09:32:42.000Z (11 months ago)
- Last Synced: 2024-10-29T17:31:56.188Z (about 1 month ago)
- Topics: activerecord, rails, rspec, rspec-matchers, ruby, ruby-on-rails
- Language: Ruby
- Homepage:
- Size: 39.1 KB
- Stars: 231
- Watchers: 3
- Forks: 33
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE.txt
Awesome Lists containing this project
- awesome-rspec - rspec-sqlimit - RSpec matcher to control SQL queries made by block of code. (Matchers)
README
# Test-Driven way of fighting N + 1 queries
RSpec matcher to control number of SQL queries executed by a block of code.
It wraps [the answer at Stack Overflow][stack-answer] by [Ryan Bigg][ryan-bigg], which based on Active Support [Notification][notification] and [Instrumentation][instrumentation] mechanisms.
For motivation and details see my [blog post "Fighting the Hydra of N+1 queries" in the Martian Chronicles][hydra].
[![Gem Version][gem-badger]][gem]
## Installation
```ruby
# Gemfile
gem "rspec-sqlimit"
```
## Usage
The gem defines matcher `exceed_query_limit` that takes maximum number of SQL requests to be made inside the block.
```ruby
require "rspec-sqlimit"
RSpec.describe "N+1 safety" do
it "doesn't send unnecessary requests to db" do
expect { User.create }.not_to exceed_query_limit(1)
end
end
```
The above specification fails with the following description:
```
Failure/Error: expect { User.create }.not_to exceed_query_limit(1)
Expected to run maximum 1 queries
The following 3 queries were invoked:
1) begin transaction (0.045 ms)
2) INSERT INTO "users" DEFAULT VALUES (0.19 ms)
3) commit transaction (148.935 ms)
```
You can restrict the matcher using regex:
```ruby
require "rspec-sqlimit"
RSpec.describe "N+1 safety" do
it "doesn't send unnecessary requests to db" do
expect { User.create }.not_to exceed_query_limit(1).with(/^INSERT/)
end
end
```
This time test passes.
When a specification with a restriction fails, you'll see an error as follows:
```ruby
require "rspec-sqlimit"
RSpec.describe "N+1 safety" do
it "doesn't send unnecessary requests to db" do
expect { User.create name: "Joe" }.not_to exceed_query_limit(0).with(/^INSERT/)
end
end
```
```
Failure/Error: expect { User.create }.not_to exceed_query_limit(0).with(/INSERT/)
Expected to run maximum 0 queries that match (?-mix:INSERT)
The following 1 queries were invoked among others (see mark ->):
1) begin transaction (0.072 ms)
-> 2) INSERT INTO "users" ("name") VALUES (?); ["Joe"] (0.368 ms)
3) commit transaction (147.559 ms)
```
In the last example you can see that binded values are shown after the query following the Rails convention.
## License
The gem is available as open source under the terms of the [MIT License](http://opensource.org/licenses/MIT).
[gem-badger]: https://img.shields.io/gem/v/rspec-sqlimit.svg?style=flat
[gem]: https://rubygems.org/gems/rspec-sqlimit
[stack-answer]: http://stackoverflow.com/a/5492207/1869912
[ryan-bigg]: http://ryanbigg.com/
[notification]: http://api.rubyonrails.org/classes/ActiveSupport/Notifications.html
[instrumentation]: http://guides.rubyonrails.org/active_support_instrumentation.html
[hook]: http://guides.rubyonrails.org/active_support_instrumentation.html#sql-active-record
[hydra]: https://evilmartians.com/chronicles/fighting-the-hydra-of-n-plus-one-queries