feat(grafeas): Provide methods to determine whether services are avai…

…lable with the currently installed versioned client (#28535)

grafeas/README.md

@@ -60,6 +60,11 @@ service such as [Google Cloud Run](https://cloud.google.com/run), this generally
 results in logs appearing alongside your application logs in the
 [Google Cloud Logging](https://cloud.google.com/logging/) service.
 
+Debug logging also requires that the versioned clients for this service be
+sufficiently recent, released after about Dec 10, 2024. If logging is not
+working, try updating the versioned clients in your bundle or installed gems:
+[grafeas-v1](https://cloud.google.com/ruby/docs/reference/grafeas-v1/latest).
+
 ## Supported Ruby Versions
 
 This library is supported on Ruby 2.7+.

grafeas/lib/grafeas.rb

@@ -36,6 +36,11 @@ module Grafeas
   # supported by that API version, and the corresponding gem is available, the
   # appropriate versioned client will be returned.
   #
+  # Raises an exception if the currently installed versioned client gem for the
+  # given API version does not support the Grafeas service.
+  # You can determine whether the method will succeed by calling
+  # {Grafeas.grafeas_available?}.
+  #
   # ## About Grafeas
   #
   # [Grafeas](https://grafeas.io) API.
@@ -67,6 +72,32 @@ def self.grafeas version: :v1, &block
     service_module = Grafeas.const_get(package_name).const_get(:Grafeas)
     service_module.const_get(:Client).new(&block)
   end
+
+  ##
+  # Determines whether the Grafeas service is supported by the current client.
+  # If true, you can retrieve a client object by calling {Grafeas.grafeas}.
+  # If false, that method will raise an exception. This could happen if the given
+  # API version does not exist or does not support the Grafeas service,
+  # or if the versioned client gem needs an update to support the Grafeas service.
+  #
+  # @param version [::String, ::Symbol] The API version to connect to. Optional.
+  #   Defaults to `:v1`.
+  # @return [boolean] Whether the service is available.
+  #
+  def self.grafeas_available? version: :v1
+    require "grafeas/#{version.to_s.downcase}"
+    package_name = Grafeas
+                   .constants
+                   .select { |sym| sym.to_s.downcase == version.to_s.downcase.tr("_", "") }
+                   .first
+    return false unless package_name
+    service_module = Grafeas.const_get package_name
+    return false unless service_module.const_defined? :Grafeas
+    service_module = service_module.const_get :Grafeas
+    service_module.const_defined? :Client
+  rescue ::LoadError
+    false
+  end
 end
 
 helper_path = ::File.join __dir__, "grafeas", "helpers.rb"

grafeas/test/grafeas/client_test.rb

@@ -41,6 +41,7 @@ def logger
   end
 
   def test_grafeas_grpc
+    skip unless Grafeas.grafeas_available?
     Gapic::ServiceStub.stub :new, DummyStub.new do
       grpc_channel = GRPC::Core::Channel.new "localhost:8888", nil, :this_channel_is_insecure
       client = Grafeas.grafeas do |config|