rubocop: fix various style issues.

test/unit/sources/nico_seiga_test.rb

@@ -35,11 +35,11 @@ module Sources
       end
 
       should "get the tags" do
-        assert(@site_1.tags.size > 0)
+        assert_not(@site_1.tags.empty?)
         first_tag = @site_1.tags.first
         assert_equal(["アニメ", "https://seiga.nicovideo.jp/tag/%E3%82%A2%E3%83%8B%E3%83%A1"], first_tag)
 
-        assert(@site_2.tags.size > 0)
+        assert_not(@site_2.tags.empty?)
         first_tag = @site_2.tags.first
         assert_equal(["アニメ", "https://seiga.nicovideo.jp/tag/%E3%82%A2%E3%83%8B%E3%83%A1"], first_tag)
       end

test/unit/sources/pawoo_test.rb

@@ -2,7 +2,7 @@ require 'test_helper'
 
 module Sources
   class PawooTest < ActiveSupport::TestCase
-    context "The source site for a https://pawoo.net/web/status/$id url"  do
+    context "The source site for a https://pawoo.net/web/status/$id url" do
       setup do
         skip "Pawoo keys not set" unless Danbooru.config.pawoo_client_id
         @site = Sources::Strategies.find("https://pawoo.net/web/statuses/1202176")
@@ -31,7 +31,7 @@ module Sources
       end
     end
 
-    context "The source site for a https://pawoo.net/$user/$id url"  do
+    context "The source site for a https://pawoo.net/$user/$id url" do
       setup do
         skip "Pawoo keys not set" unless Danbooru.config.pawoo_client_id
         @site = Sources::Strategies.find("https://pawoo.net/@evazion/19451018")
@@ -82,7 +82,7 @@ module Sources
       end
     end
 
-    context "The source site for a https://img.pawoo.net/ url"  do
+    context "The source site for a https://img.pawoo.net/ url" do
       setup do
         skip "Pawoo keys not set" unless Danbooru.config.pawoo_client_id
         @url = "https://img.pawoo.net/media_attachments/files/001/298/028/original/55a6fd252778454b.mp4"

test/unit/sources/pixiv_test.rb

@@ -59,9 +59,9 @@ module Sources
         should "capture the frame data" do
           assert_equal(2, @site.ugoira_frame_data.size)
           if @site.ugoira_frame_data[0]["file"]
-            assert_equal([{"file"=>"000000.jpg", "delay"=>125}, {"file"=>"000001.jpg", "delay"=>125}], @site.ugoira_frame_data)
+            assert_equal([{"file" => "000000.jpg", "delay" => 125}, {"file" => "000001.jpg", "delay" => 125}], @site.ugoira_frame_data)
           else
-            assert_equal([{"delay_msec"=>125}, {"delay_msec"=>125}], @site.ugoira_frame_data)
+            assert_equal([{"delay_msec" => 125}, {"delay_msec" => 125}], @site.ugoira_frame_data)
           end
         end
       end
@@ -171,7 +171,7 @@ module Sources
 
         should "get the full size image url" do
           assert_equal("https://i.pximg.net/img-original/img/2017/08/18/00/09/21/64476642_p0.jpg", @site.image_url)
-        end        
+        end
 
         should "get the full size image url for the canonical url" do
           assert_equal("https://i.pximg.net/img-original/img/2017/08/18/00/09/21/64476642_p0.jpg", @site.canonical_url)
@@ -223,7 +223,7 @@ module Sources
             "mutsu_(kantai_collection)" => "陸奥",
             "fate/grand_order" => "Fate/GrandOrder",
             "fate" => "",
-            "foo" => "",
+            "foo" => ""
           }
 
           tags.each do |tag, other_names|

test/unit/sources/twitter_test.rb

@@ -213,7 +213,7 @@ module Sources
       should "get the tags" do
         tags = [
           %w[foo https://twitter.com/hashtag/foo],
-          %w[ホワイトデー https://twitter.com/hashtag/ホワイトデー],
+          %w[ホワイトデー https://twitter.com/hashtag/ホワイトデー]
         ]
 
         assert_equal(tags, @site.tags)