Prevent Minitest reporters from being mutated after LSP hooks (#3518)

Author: vinistock

jekyll/test_explorer.markdown

@@ -126,27 +126,9 @@ ruby-lsp-test-exec bundle exec rspec spec/example_spec.rb
 When tests are running through any execution mode, we set the `RUBY_LSP_TEST_RUNNER` environment variable to allow
 users to customize behavior of their test suite if needed.
 
-{: .important }
-The Ruby LSP uses a custom test reporter to be able to communicate between extension and server. Some gems that modify
-reporters may break this integration. The `RUBY_LSP_TEST_RUNNER` variable can be used to turn off these gems only when
-running under the Ruby LSP's integrations.
-
 {: .important }
 Using coverage mode **does not require any extra dependencies or configuration** for collecting the coverage data. This is done automatically by the Ruby LSP through Ruby's built-in coverage API.
 
-For example
-
-```ruby
-# test/test_helper.rb
-
-unless ENV["RUBY_LSP_TEST_RUNNER"]
-  # Minitest reporters cannot be used when running through the Ruby LSP integrations as it breaks our custom reporter
-
-  require "minitest/reporters"
-  Minitest::Reporters.use!(...)
-end
-```
-
 Users can also differentiate between the mode of execution, which is the value of the `RUBY_LSP_TEST_RUNNER` variable:
 
 ```ruby

lib/ruby_lsp/test_reporters/minitest_reporter.rb

@@ -30,6 +30,30 @@ def record(result)
     end
   end
 
+  # This patch is here to prevent other gems from overriding or adding more Minitest reporters. Otherwise, they may
+  # break the integration between the server and extension
+  module PreventReporterOverridePatch
+    @lsp_reporters = [] #: Array[Minitest::AbstractReporter]
+
+    class << self
+      #: Array[Minitest::AbstractReporter]
+      attr_accessor :lsp_reporters
+    end
+
+    # Patch the writer to prevent replacing the entire array
+    #: (untyped) -> void
+    def reporters=(reporters)
+      # Do nothing. We don't want other gems to override our reporter
+    end
+
+    # Patch the reader to prevent appending more reporters. This method always returns a temporary copy of the real
+    # reporters so that if any gem mutates it, it continues to return the original reporters
+    #: -> Array[untyped]
+    def reporters
+      PreventReporterOverridePatch.lsp_reporters.dup
+    end
+  end
+
   class MinitestReporter < Minitest::AbstractReporter
     class << self
       #: (Hash[untyped, untyped]) -> void
@@ -45,6 +69,8 @@ def minitest_plugin_init(_options)
 
         # Add the JSON RPC reporter
         reporters << MinitestReporter.new
+        PreventReporterOverridePatch.lsp_reporters = reporters
+        Minitest.reporter.class.prepend(PreventReporterOverridePatch)
       end
     end