Add attachments support for Slack::Web::Api::Endpoints::Chat.chat_update

lib/slack/web/api/endpoints/chat.rb

@@ -82,8 +82,14 @@ def chat_postMessage(options = {})
           def chat_update(options = {})
             throw ArgumentError.new('Required arguments :ts missing') if options[:ts].nil?
             throw ArgumentError.new('Required arguments :channel missing') if options[:channel].nil?
-            throw ArgumentError.new('Required arguments :text missing') if options[:text].nil?
+            throw ArgumentError.new('Required arguments :text or :attachments missing') if options[:text].nil? && options[:attachments].nil?
             options = options.merge(channel: channels_id(options)['channel']['id']) if options[:channel]
+            # attachments must be passed as an encoded JSON string
+            if options.key?(:attachments)
+              attachments = options[:attachments]
+              attachments = JSON.dump(attachments) unless attachments.is_a?(String)
+              options = options.merge(attachments: attachments)
+            end
             post('chat.update', options)
           end
         end

spec/slack/web/api/endpoints/custom_specs/chat_spec.rb

@@ -30,4 +30,40 @@
       end
     end
   end
+
+  context 'chat_update' do
+    let(:ts) { '1405894322.002768' }
+    it 'automatically converts attachments into JSON' do
+      expect(client).to receive(:post).with(
+        'chat.update',
+        attachments: '[]',
+        channel: 'channel',
+        text: 'text',
+        ts: ts
+      )
+      client.chat_update(attachments: [], channel: 'channel', text: 'text', ts: ts)
+    end
+    context 'ts arguments' do
+      it 'requires ts' do
+        expect { client.chat_update(channel: 'channel') }.to raise_error ArgumentError, /Required arguments :ts missing>/
+      end
+    end
+    context 'text and attachment arguments' do
+      it 'requires text or attachments' do
+        expect { client.chat_update(channel: 'channel', ts: ts) }.to raise_error ArgumentError, /Required arguments :text or :attachments missing/
+      end
+      it 'only text' do
+        expect(client).to receive(:post).with('chat.update', hash_including(text: 'text'))
+        expect { client.chat_update(channel: 'channel', text: 'text', ts: ts) }.to_not raise_error
+      end
+      it 'only attachments' do
+        expect(client).to receive(:post).with('chat.update', hash_including(attachments: '[]'))
+        expect { client.chat_update(attachments: [], channel: 'channel', ts: ts) }.to_not raise_error
+      end
+      it 'both text and attachments' do
+        expect(client).to receive(:post).with('chat.update', hash_including(text: 'text', attachments: '[]'))
+        expect { client.chat_update(attachments: [], channel: 'channel', text: 'text', ts: ts) }.to_not raise_error
+      end
+    end
+  end
 end