Correct way to fix material_delete issue #78.

Author: Eric-Guo

lib/wechat/api.rb

@@ -143,7 +143,7 @@ def material_add(type, file)
     end
 
     def material_delete(media_id)
-      post 'material/del_material', media_id: media_id
+      post 'material/del_material', JSON.generate(media_id: media_id)
     end
 
     def custom_message_send(message)

lib/wechat/http_client.rb

@@ -22,7 +22,7 @@ def get(path, get_header = {})
     def post(path, payload, post_header = {})
       request(path, post_header) do |url, header|
         params = header.delete(:params)
-        httprb.headers(header).post(url, params: params, body: payload.to_json, ssl_context: ssl_context)
+        httprb.headers(header).post(url, params: params, body: payload, ssl_context: ssl_context)
       end
     end
 

spec/lib/wechat/api_spec.rb

@@ -470,8 +470,9 @@
     specify 'will post material/del_material with access_token and media_id in payload' do
       media_id = 'media_id'
       material_delete_result = { errcode: 0, errmsg: 'deleted' }
+      payload = { media_id: media_id }
       expect(subject.client).to receive(:post)
-        .with('material/del_material', { media_id: media_id },
+        .with('material/del_material', payload.to_json,
               params: { access_token: 'access_token' }).and_return(material_delete_result)
       expect(subject.material_delete(media_id)).to eq material_delete_result
     end