[spec/] Avoid ENV overwrite in specs

The APPLIANCE_PG_DATA and APPLIANCE_PG_SERVICE environment variables are
used by both the database_replication_spec.rb and postgres_admin_spec.rb
specs.

The previous implementation, specs in both database_replication_spec.rb
and postgres_admin_spec.rb would delete/overwrite the ENV variables that
were assumed to be set for the other to run it's processes.  In this
case, it is simpler to store the variable in a tmp variable before
overwriting it for the purposes of the spec in question, and then reset
the var to it's original value when the spec is finished.  That way
other specs will be able to use it with out issue, regardless of what
order the specs are triggered from.

Author: NickLaMuro

spec/database_replication_spec.rb

@@ -77,13 +77,15 @@
     end
 
     before do
-      ENV["APPLIANCE_PG_DATA"] = "/var/lib/pgsql"
+      @appliance_pg_data_old      = ENV["APPLIANCE_PG_DATA"]
+      @appliance_pg_service_old   = ENV["APPLIANCE_PG_DATA"]
+      ENV["APPLIANCE_PG_DATA"]    = "/var/lib/pgsql"
       ENV["APPLIANCE_PG_SERVICE"] = "postgresql-9.5"
     end
 
     after do
-      ENV.delete("APPLIANCE_PG_DATA")
-      ENV.delete("APPLIANCE_PG_SERVICE")
+      ENV["APPLIANCE_PG_DATA"]    = @appliance_pg_data_old
+      ENV["APPLIANCE_PG_SERVICE"] = @appliance_pg_service_old
     end
 
     it "returns the correct contents" do

spec/postgres_admin_spec.rb

@@ -274,23 +274,24 @@
   end
 
   context "ENV dependent" do
-    after do
-      ENV.delete_if { |k, _| k.start_with?("APPLIANCE") }
-    end
-
     [%w(data_directory     APPLIANCE_PG_DATA            /some/path      true),
      %w(service_name       APPLIANCE_PG_SERVICE         postgresql          ),
      %w(package_name       APPLIANCE_PG_PACKAGE_NAME    postgresql-server   ),
      %w(template_directory APPLIANCE_TEMPLATE_DIRECTORY /some/path      true),
      %w(mount_point        APPLIANCE_PG_MOUNT_POINT     /mount/point    true)
     ].each do |method, var, value, pathname_required|
       it method.to_s do
-        ENV[var] = value
-        result = described_class.public_send(method)
-        if pathname_required
-          expect(result.join("abc/def").to_s).to eql "#{value}/abc/def"
-        else
-          expect(result).to eql value
+        begin
+          old_var = ENV[var]
+          ENV[var] = value
+          result = described_class.public_send(method)
+          if pathname_required
+            expect(result.join("abc/def").to_s).to eql "#{value}/abc/def"
+          else
+            expect(result).to eql value
+          end
+        ensure
+          ENV[var] = old_var
         end
       end
     end
@@ -301,9 +302,14 @@
 
     context "with a data directory" do
       around do |example|
-        Dir.mktmpdir do |dir|
-          ENV["APPLIANCE_PG_DATA"] = dir
-          example.run
+        begin
+          old_appliance_pg_data = ENV["APPLIANCE_PG_DATA"]
+          Dir.mktmpdir do |dir|
+            ENV["APPLIANCE_PG_DATA"] = dir
+            example.run
+          end
+        ensure
+          ENV["APPLIANCE_PG_DATA"] = old_appliance_pg_data
         end
       end