Commit fda4d554 authored by Lin Jen-Shin's avatar Lin Jen-Shin

Add docs around expect_next_instance_of

parent 562f357b
......@@ -92,6 +92,54 @@ describe API::Labels do
end
```
## Avoid using `allow_any_instance_of` in RSpec
### Why
* Because it is not isolated therefore it might be broken at times.
* Because it doesn't work whenever the method we want to stub was defined
in a prepended module, which is very likely the case in EE. We could see
error like this:
1.1) Failure/Error: allow_any_instance_of(ApplicationSetting).to receive_messages(messages)
Using `any_instance` to stub a method (elasticsearch_indexing) that has been defined on a prepended module (EE::ApplicationSetting) is not supported.
### Alternative: `expect_next_instance_of`
Instead of writing:
```ruby
# Don't do this:
allow_any_instance_of(Project).to receive(:add_import_job)
```
We could write:
```ruby
# Do this:
expect_next_instance_of(Project) do |project|
expect(project).to receive(:add_import_job)
end
```
If we also want to expect the instance was initialized with some particular
arguments, we could also pass it to `expect_next_instance_of` like:
```ruby
# Do this:
expect_next_instance_of(MergeRequests::RefreshService, project, user) do |refresh_service|
expect(refresh_service).to receive(:execute).with(oldrev, newrev, ref)
end
```
This would expect the following:
```ruby
# Above expects:
refresh_service = MergeRequests::RefreshService.new(project, user)
refresh_service.execute(oldrev, newrev, ref)
```
## Do not `rescue Exception`
See ["Why is it bad style to `rescue Exception => e` in Ruby?"][Exception].
......
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