added tests for the posts controller's upload action

Author: Oaphi

test/controllers/posts/upload_test.rb

@@ -0,0 +1,28 @@
+require 'test_helper'
+
+class PostsControllerTest < ActionController::TestCase
+  include Devise::Test::ControllerHelpers
+
+  test 'upload should correctly check file types' do
+    sign_in users(:standard_user)
+
+    try_upload_file('not_uploadable.json', 'application/json')
+
+    assert_response(:bad_request)
+    assert_valid_json_response
+    assert_not_nil JSON.parse(response.body)['message']
+
+    try_upload_file('uploadable_png.png', 'image/png')
+
+    assert_json_success
+    assert_not_nil JSON.parse(response.body)['link']
+  end
+
+  private
+
+  def try_upload_file(path, mime)
+    post :upload, params: {
+      file: file_fixture_upload(path, mime)
+    }
+  end
+end

test/fixtures/files/not_uploadable.json

@@ -0,0 +1,5 @@
+{
+  "message": "this file should not be possible to upload",
+  "answer": 42,
+  "question": null
+}