Fix Ensure check methods can't modify tokens array

The functionality originally released in rodjek#296
was probably broken at the time, possibly made worse by later rubocop
'fixes' and also incompatible with ruby 3.4.

We now look at the stack trace only from the `tokens` wrapper method in
`checkplugin`.

Fixes #225

Author: alexjfisher

.github/workflows/ci.yml

@@ -22,6 +22,7 @@ jobs:
           - '2.7'
           - '3.2'
           - '3.3'
+          - '3.4'
     name: "spec (ruby ${{ matrix.ruby_version }})"
     uses: "puppetlabs/cat-github-actions/.github/workflows/gem_ci.yml@main"
     secrets: "inherit"
@@ -37,6 +38,7 @@ jobs:
           - '2.7'
           - '3.2'
           - '3.3'
+          - '3.4'
     name: "acceptance (ruby ${{ matrix.ruby_version }})"
     needs: "spec"
     uses: "puppetlabs/cat-github-actions/.github/workflows/gem_acceptance.yml@main"

lib/puppet-lint/checkplugin.rb

@@ -55,7 +55,9 @@ def fix_problems
   #
   # Returns an Array of PuppetLint::Lexer::Token objects.
   def tokens
-    PuppetLint::Data.tokens
+    # When called from a plugins `check` method, the tokens returned should be a copy
+    called_from_check = (caller_locations(1..1).first.label == 'check')
+    PuppetLint::Data.tokens(duplicate: called_from_check)
   end
 
   def add_token(index, token)

lib/puppet-lint/data.rb

@@ -38,37 +38,14 @@ def tokens=(tokens)
       @defaults_indexes = nil
     end
 
-    # @api private
-    def ruby1?
-      @ruby1 = RbConfig::CONFIG['MAJOR'] == '1' if @ruby1.nil?
-      @ruby1
-    end
-
     # Get the tokenised manifest.
     #
+    # @param duplicate [Boolean] if true, returns a duplicate of the token array.
     # @return [Array[PuppetLint::Lexer::Token]]
     #
     # @api public
-    def tokens
-      calling_method = if ruby1?
-                         begin
-                           caller[0][%r{`.*'}][1..-2] # rubocop:disable Performance/Caller
-                         rescue NoMethodError
-                           caller[1][%r{`.*'}][1..-2] # rubocop:disable Performance/Caller
-                         end
-                       else
-                         begin
-                           caller(0..0).first[%r{`.*'}][1..-2]
-                         rescue NoMethodError
-                           caller(1..1).first[%r{`.*'}][1..-2]
-                         end
-                       end
-
-      if calling_method == 'check'
-        @tokens.dup
-      else
-        @tokens
-      end
+    def tokens(duplicate: false)
+      duplicate ? @tokens.dup : @tokens
     end
 
     # Add new token.