Test against rails 8.0

[jewilmeer]

As rails 8 came out, and not a lot has changed internally since 7.2, it might just work :-)

[k-tsuchiya-jp]

https://github.com/railsadminteam/rails_admin/actions/runs/11738544873/job/32701267375?pr=3702#step:7:30

From Rails 8.0, it looks like the version of sqlite3 needs to be upgraded to v2.1 or higher.

[jewilmeer]

indeed, I upgraded it, and now it seems to work

[jewilmeer]

It looks like a lot of unrelated things are broken, not sure how to proceed.

[dsinn]

@jewilmeer Indeed, I was able to reproduce the issue on master. I suspect that because the json gem isn't pinned, the latest CI runs install a version that is greater than 2.7.6, the newer versions' JSON.pretty_generate({}) behaves differently, as it no longer contains a newline. Compare:

Old behaviour	New behaviour
$ irb irb(main):001> require "json" => true irb(main):002> JSON::VERSION => "2.7.6" irb(main):003> puts JSON.pretty_generate({}) { } => nil	$ irb irb(main):001> require "json" => true irb(main):002> JSON::VERSION => "2.8.2" irb(main):003> puts JSON.pretty_generate({}) {} => nil

The test fails because RailsAdmin's Json field class calls JSON.pretty_generate, and the test's regex is expecting at least one newline from its result. As a quick test, I made the following change, and the tests pass:

diff --git a/spec/rails_admin/config/fields/types/json_spec.rb b/spec/rails_admin/config/fields/types/json_spec.rb
index a1e03958..a749d930 100644
--- a/spec/rails_admin/config/fields/types/json_spec.rb
+++ b/spec/rails_admin/config/fields/types/json_spec.rb
@@ -24,7 +24,7 @@ RSpec.describe RailsAdmin::Config::Fields::Types::Json do
     it 'returns correct value for empty json' do
       allow(object).to receive(:json_field) { {} }
       actual = field.with(bindings).formatted_value
-      expect(actual).to match(/{\n+}/)
+      expect(actual).to match(/{\n*}/)
     end
 
     it 'retuns correct value' do
@@ -72,7 +72,7 @@ RSpec.describe RailsAdmin::Config::Fields::Types::Json do
     it 'returns correct value for empty json' do
       allow(object).to receive(:json_field) { {} }
       actual = field.with(bindings).export_value
-      expect(actual).to match(/{\n+}/)
+      expect(actual).to match(/{\n*}/)
     end
 
     it 'returns correct value' do

I don't see any need for the newline, so I'd lean towards just updating the test (whether to split the change into a separate PR is up to you and the maintainers), but I'm also not a frequent user of RailsAdmin.