Make transit_gateway have_attachment work with names

With this change, it is now possible to check transit gateways have
attachments based on the attachment name instead of just id. The name
can either be a string or a regex.

`have_attachment` now also works if `should exist` hasn't been called
first (where `@id` wasn't initialised).

doc/_resource_types/transit_gateway.md

@@ -22,3 +22,25 @@ describe transit_gateway('my-tgw') do
   its(:transit_gateway_id) { should eq 'tgw-1234567890abcdefg' }
 end
 ```
+### have_attachment
+
+#### using attachment id
+```ruby
+describe transit_gateway('tgw-1234567890abcdefg') do
+  it { should have_attachment('tgw-attach-1234567890abcdefg') }
+end
+```
+
+#### using attachment name
+```ruby
+describe transit_gateway('tgw-1234567890abcdefg') do
+  it { should have_attachment('my-prod-tgw-attachment') }
+end
+```
+
+#### using regular expression attachment name
+```ruby
+describe transit_gateway('tgw-1234567890abcdefg') do
+  it { should have_attachment(/^my-\w+-tgw-attachment$/) }
+end
+```

doc/resource_types.md

@@ -3884,6 +3884,27 @@ end
 
 ### have_attachment
 
+#### using attachment id
+```ruby
+describe transit_gateway('tgw-1234567890abcdefg') do
+  it { should have_attachment('tgw-attach-1234567890abcdefg') }
+end
+```
+
+#### using attachment name
+```ruby
+describe transit_gateway('tgw-1234567890abcdefg') do
+  it { should have_attachment('my-prod-tgw-attachment') }
+end
+```
+
+#### using regular expression attachment name
+```ruby
+describe transit_gateway('tgw-1234567890abcdefg') do
+  it { should have_attachment(/^my-\w+-tgw-attachment$/) }
+end
+```
+
 ### have_tag
 
 ### its(:transit_gateway_id), its(:transit_gateway_arn), its(:state), its(:owner_id), its(:description), its(:creation_time)

lib/awspec/type/transit_gateway.rb

@@ -18,9 +18,21 @@ def options
     end
 
     def has_attachment?(att_id)
-      atts = find_tgw_attachments_by_tgw_id(@id)
-      ret = atts.find_all { |att| att.transit_gateway_attachment_id == att_id }
-      ret.any?
+      atts = find_tgw_attachments_by_tgw_id(id)
+
+      atts.any? do |att|
+        att.transit_gateway_attachment_id == att_id || attachment_has_name?(att, att_id)
+      end
+    end
+
+    private
+
+    def attachment_has_name?(attachment, name)
+      if name.is_a?(Regexp)
+        attachment.tags.any? { |tag| tag.key == 'Name' && (name =~ tag.value) }
+      else
+        attachment.tags.any? { |tag| tag.key == 'Name' && tag.value == name }
+      end
     end
   end
 end

spec/type/transit_gateway_spec.rb

@@ -21,3 +21,23 @@
   it { should exist }
   its(:transit_gateway_id) { should eq 'tgw-1234567890abcdefg' }
 end
+
+describe transit_gateway('my-transit-gateway') do
+  it { should exist }
+  it 'supports `have_attachment` by attachment name' do
+    should have_attachment('my-transit-gateway-attachment')
+  end
+end
+
+describe transit_gateway('my-transit-gateway') do
+  it { should exist }
+  it 'supports `have_attachment` by attachment regular expression' do
+    should have_attachment(/my-transit-gateway-attachment/)
+  end
+end
+
+describe transit_gateway('my-transit-gateway') do
+  it 'supports have_attachment when `should exist` hasn\'t been called first' do
+    should have_attachment('tgw-attach-1234567890abcdefg')
+  end
+end