Run rspec tests locally, easily

We test our four production nameservers using `rspec`, and although that
worked fine when we used GitHub actions with a curated Ruby, it didn't
always work as well when running locally.

With this commit we introduce a Gemfile which has the necessary Ruby
dependencies, which make it easer to run the tests locally.

Gemfile

@@ -0,0 +1,6 @@
+source 'https://rubygems.org'
+
+ruby '3.4.2'
+
+gem 'rspec'
+gem 'rubocop'

Gemfile.lock

@@ -0,0 +1,63 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    ast (2.4.3)
+    diff-lcs (1.6.2)
+    json (2.13.1)
+    language_server-protocol (3.17.0.5)
+    lint_roller (1.1.0)
+    parallel (1.27.0)
+    parser (3.3.8.0)
+      ast (~> 2.4.1)
+      racc
+    prism (1.4.0)
+    racc (1.8.1)
+    rainbow (3.1.1)
+    regexp_parser (2.10.0)
+    rspec (3.13.1)
+      rspec-core (~> 3.13.0)
+      rspec-expectations (~> 3.13.0)
+      rspec-mocks (~> 3.13.0)
+    rspec-core (3.13.5)
+      rspec-support (~> 3.13.0)
+    rspec-expectations (3.13.5)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.13.0)
+    rspec-mocks (3.13.5)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.13.0)
+    rspec-support (3.13.4)
+    rubocop (1.79.0)
+      json (~> 2.3)
+      language_server-protocol (~> 3.17.0.2)
+      lint_roller (~> 1.1.0)
+      parallel (~> 1.10)
+      parser (>= 3.3.0.2)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 2.9.3, < 3.0)
+      rubocop-ast (>= 1.46.0, < 2.0)
+      ruby-progressbar (~> 1.7)
+      tsort (>= 0.2.0)
+      unicode-display_width (>= 2.4.0, < 4.0)
+    rubocop-ast (1.46.0)
+      parser (>= 3.3.7.2)
+      prism (~> 1.4)
+    ruby-progressbar (1.13.0)
+    tsort (0.2.0)
+    unicode-display_width (3.1.4)
+      unicode-emoji (~> 4.0, >= 4.0.4)
+    unicode-emoji (4.0.4)
+
+PLATFORMS
+  arm64-darwin-24
+  ruby
+
+DEPENDENCIES
+  rspec
+  rubocop
+
+RUBY VERSION
+   ruby 3.4.2p28
+
+BUNDLED WITH
+   2.6.6

README.md

@@ -157,7 +157,8 @@ as ARM64 (AWS Graviton, Apple M1/M2).
 - `spec/` contains the tests for the production nameservers. To run
   the tests locally:
   ```bash
-  DOMAINS=nip.io,sslip.io rspec --format documentation --color spec
+  bundle
+  DOMAINS=nip.io,sslip.io bundle exec rspec --format documentation --color spec
   ```
 - `k8s/document_root_sslip.io/` contains the HTML content of the sslip.io
   website.