[Shared] Defined AWS domains as constants and added a test to validat…

…e that the correct domain is returned for a given region.

Signed-off-by: Giacomo Marciani <mgiacomo@amazon.com>

cookbooks/aws-parallelcluster-shared/libraries/environment.rb

@@ -2,17 +2,22 @@ def aws_region
   node['cluster']['region']
 end
 
+CLASSIC_AWS_DOMAIN = "amazonaws.com".freeze
+CHINA_AWS_DOMAIN = "amazonaws.com.cn".freeze
+US_ISO_AWS_DOMAIN = "c2s.ic.gov".freeze
+US_ISOB_AWS_DOMAIN = "sc2s.sgov.gov".freeze
+
 def aws_domain
   # Get the aws domain name
   region = aws_region
   if region.start_with?("cn-")
-    "amazonaws.com.cn"
+    CHINA_AWS_DOMAIN
   elsif region.start_with?("us-iso-")
-    "c2s.ic.gov"
+    US_ISO_AWS_DOMAIN
   elsif region.start_with?("us-isob-")
-    "sc2s.sgov.gov"
+    US_ISOB_AWS_DOMAIN
   else
-    "amazonaws.com"
+    CLASSIC_AWS_DOMAIN
   end
 end
 

cookbooks/aws-parallelcluster-shared/spec/unit/libraries/environment_spec.rb

@@ -0,0 +1,35 @@
+require_relative '../../../libraries/environment'
+require 'spec_helper'
+
+describe 'aws_domain' do
+  shared_examples 'a valid aws_domain function' do |region, expected_aws_domain|
+    it 'returns the correct AWS domain' do
+      allow_any_instance_of(Object).to receive(:aws_region).and_return(region)
+      # We must force aws_domain to call the original function because
+      # the spec_helper configures aws_domain to return a mocked value for all rspec tests.
+      allow_any_instance_of(Object).to receive(:aws_domain).and_call_original
+
+      expect(aws_domain).to eq(expected_aws_domain)
+    end
+  end
+
+  context 'when in CN region' do
+    include_examples 'a valid aws_domain function', 'cn-WHATEVER', 'amazonaws.com.cn'
+  end
+
+  context 'when in US-ISO region' do
+    include_examples 'a valid aws_domain function', 'us-iso-WHATEVER', 'c2s.ic.gov'
+  end
+
+  context 'when in US-ISOB region' do
+    include_examples 'a valid aws_domain function', 'us-isob-', 'sc2s.sgov.gov'
+  end
+
+  context 'when in GovCloud region' do
+    include_examples 'a valid aws_domain function', 'us-gov-WHATEVER', 'amazonaws.com'
+  end
+
+  context 'when in whatever else region' do
+    include_examples 'a valid aws_domain function', 'WHATEVER-ELSE', 'amazonaws.com'
+  end
+end