Fix documentation rake tasks to support Rubocop 0.75

Rubocop 0.75 changed the initializer for RuboCop::Cop::MessageAnnotator
in a breaking way, however rubocop-rspec does not pin to a strict
version. This commit selects the right interface depending on the loaded
version of Rubocop.

Author: Nick Campbell

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Master (Unreleased)
 
+* Fix documentation rake task to support Rubocop 0.75. ([@nickcampbell18][])
+
 ## 1.36.0 (2019-09-27)
 
 * Fix `RSpec/DescribedClass`'s error when `described_class` is used as part of a constant. ([@pirj][])
@@ -452,3 +454,4 @@ Compatibility release so users can upgrade RuboCop to 0.51.0. No new features.
 [@foton]: https://github.com/foton
 [@nc-holodakg]: https://github.com/nc-holodakg
 [@onumis]: https://github.com/onumis
+[@nickcampbell18]: https://github.com/nickcampbell18

tasks/cops_documentation.rake

@@ -138,9 +138,32 @@ task generate_cops_documentation: :yard_for_generate_documentation do
   end
   # rubocop:enable Metrics/MethodLength
 
+  def cop_urls(config, cop)
+    rubocop_version = Gem::Version.new(RuboCop::Version::STRING)
+
+    # Since Rubocop v0.75.0 and above, MessageAnnotator#new changed from:
+    #   def initialize(config, cop_config, options)
+    # to:
+    #   def initialize(config, cop_name, cop_config, options)
+    #
+    # Since this library has a loose Rubocop dependency, we select the
+    # right arguments based on the installed version.
+    #
+    # TODO: When Rubocop < 0.75 is no longer supported, remove the second half
+    # of this condition.
+
+    if rubocop_version >= Gem::Version.new('0.75.0')
+      RuboCop::Cop::MessageAnnotator.new(
+        config, cop.name, config.for_cop(cop), {}
+      ).urls
+    else
+      RuboCop::Cop::MessageAnnotator.new(config, config.for_cop(cop), {}).urls
+    end
+  end
+
   def references(config, cop)
-    cop_config = config.for_cop(cop)
-    urls = RuboCop::Cop::MessageAnnotator.new(config, cop_config, {}).urls
+    urls = cop_urls(config, cop)
+
     return '' if urls.empty?
 
     content = h3('References')