Fix #4522: Sidebar doesn't show most searched tags at certain times of day.

Revert back to previous workaround of fetching previous day if current
day returns no result. A terrible hack, really we should convert dates
to Reportbooru's timezone, but that has other complications.

test/unit/reportbooru_service_test.rb

@@ -4,20 +4,20 @@ class ReportbooruServiceTest < ActiveSupport::TestCase
   def setup
     @service = ReportbooruService.new(reportbooru_server: "http://localhost:1234")
     @post = create(:post)
-    @date = "2000-01-01"
+    @date = Date.parse("2000-01-01")
   end
 
   context "#popular_posts" do
     should "return the list of popular posts on success" do
-      body = "[[#{@post.id},100.0]]"
-      @service.http.expects(:get).with("http://localhost:1234/post_views/rank?date=#{@date}").returns(HTTP::Response.new(status: 200, body: body, version: "1.1"))
+      mock_post_view_rankings(@date, [[@post.id, 100]])
 
       posts = @service.popular_posts(@date)
       assert_equal([@post], posts)
     end
 
     should "return nothing on failure" do
-      @service.http.expects(:get).with("http://localhost:1234/post_views/rank?date=#{@date}").returns(HTTP::Response.new(status: 500, body: "", version: "1.1"))
+      Danbooru::Http.any_instance.expects(:get).with("http://localhost:1234/post_views/rank?date=#{@date}").returns(HTTP::Response.new(status: 500, body: "", version: "1.1"))
+      Danbooru::Http.any_instance.expects(:get).with("http://localhost:1234/post_views/rank?date=#{@date.yesterday}").returns(HTTP::Response.new(status: 500, body: "", version: "1.1"))
 
       assert_equal([], @service.popular_posts(@date))
     end