add guard environment

Guard is indispensable for TDD red/green coding.

https://github.com/guard/guard#readme

crowbar_framework/Gemfile

@@ -63,6 +63,8 @@ unless ENV["PACKAGING"] && ENV["PACKAGING"] == "yes"
     gem "byebug", "~> 8.2.2"
     gem "derailed_benchmarks", "~> 1.3.0"
     gem "stackprof", "~> 0.2.8"
+    gem "guard-rspec"
+    gem "guard-bundler"
   end
 
   group :test do

crowbar_framework/Guardfile

@@ -0,0 +1,50 @@
+#!/usr/bin/ruby
+#
+# More info at https://github.com/guard/guard#readme
+
+guard_opts = {
+  cmd: "bundle exec rspec --fail-fast",
+  all_on_start:   true,
+  all_after_pass: true,
+  failed_mode: :focus
+}
+
+DEBUG = false
+
+def reload(target)
+  puts "-> #{target}" if DEBUG
+  target
+end
+
+def all_specs;      reload "all_specs";      "spec"           end
+def library_specs;  reload "library_specs";  "spec/libraries" end
+def provider_specs; reload "provider_specs"; "spec/providers" end
+
+group :rspec do
+  guard :rspec, guard_opts do
+    watch('app/controllers/application_controller.rb') {
+      "spec/controllers"
+    }
+    watch(%r{^app/(.+)\.rb$})              { |m| "spec/#{m[1]}_spec.rb" }
+    watch(%r{^app/(.*)(\.erb|\.haml)$})    { |m| "spec/#{m[1]}#{m[2]}_spec.rb" }
+    watch(%r{^lib/(.+)\.rb$})              { |m| "spec/lib/#{m[1]}_spec.rb" }
+    watch(%r{^app/controllers/(.+)_(controller)\.rb$}) { |m|
+      [
+        "spec/routing/#{m[1]}_routing_spec.rb",
+        "spec/#{m[2]}s/#{m[1]}_#{m[2]}_spec.rb",
+        "spec/acceptance/#{m[1]}_spec.rb"
+      ]
+    }
+    watch(%r{^Gemfile$})                   { all_specs }
+    watch(%r{^Gemfile.lock$})              { all_specs }
+    watch(%r{^spec/spec_helper\.rb$})      { all_specs }
+    watch(%r{^spec/helpers/.+\.rb$})       { all_specs }
+    watch(%r{^spec/.+_spec\.rb$})
+  end
+end
+
+group :bundler do
+  guard :bundler do
+    watch("Gemfile")
+  end
+end