diff --git a/test/functional/autocomplete_controller_test.rb b/test/functional/autocomplete_controller_test.rb
index 3529c7c30..5acb481af 100644
--- a/test/functional/autocomplete_controller_test.rb
+++ b/test/functional/autocomplete_controller_test.rb
@@ -1,59 +1,78 @@
 require "test_helper"
 
 class AutocompleteControllerTest < ActionDispatch::IntegrationTest
-  def autocomplete(query, type)
+  def autocomplete(query, type = "tag_query")
     get autocomplete_index_path(search: { query: query, type: type })
     assert_response :success
 
     response.parsed_body.css("li").map { |html| html["data-autocomplete-value"] }
   end
 
-  def assert_autocomplete_equals(expected_value, query, type)
+  def assert_autocomplete_equals(expected_value, query, type = "tag_query")
     assert_equal(expected_value, autocomplete(query, type))
   end
 
   context "Autocomplete controller" do
     context "index action" do
-      setup do
-        create(:tag, name: "azur_lane")
-        create(:tag, name: "android")
-        create(:tag, name: "original")
-      end
-
       should "work for opensearch queries" do
+        create(:tag, name: "azur_lane")
+
         get autocomplete_index_path(search: { query: "azur", type: "opensearch" }), as: :json
 
         assert_response :success
         assert_equal(["azur", ["azur_lane"]], response.parsed_body)
       end
 
-      should "work for tag queries" do
-        assert_autocomplete_equals(["azur_lane"], "azur", "tag_query")
-        assert_autocomplete_equals(["azur_lane"], "AZUR", "tag_query")
+      should "work for simple tag queries" do
+        create(:tag, name: "azur_lane")
 
-        assert_autocomplete_equals(["rating:sensitive"], "rating:s", "tag_query")
-        assert_autocomplete_equals(["rating:sensitive"], "-rating:s", "tag_query")
+        assert_autocomplete_equals(["azur_lane"], "azur")
+        assert_autocomplete_equals(["azur_lane"], "AZUR")
+
+        assert_autocomplete_equals(["rating:sensitive"], "rating:s")
+        assert_autocomplete_equals(["rating:sensitive"], "-rating:s")
+      end
+
+      should "match tags containing the given words" do
+        create(:tag, name: "short_hair", post_count: 15_000)
+        create(:tag, name: "long_hair", post_count: 10_000)
+        create(:tag, name: "very_long_hair", post_count: 5_000)
+        create(:tag, name: "absurdly_long_hair", post_count: 1_000)
+        create(:tag, name: "souryuu_asuka_langley")
+        create(:tag, name: "crying_with_eyes_open")
+        create(:tag, name: "open_mouth")
+        create(:tag, name: "black_hair")
+        create(:tag_alias, antecedent_name: "dark_hair", consequent_name: "black_hair")
+
+        assert_autocomplete_equals(%w[long_hair very_long_hair absurdly_long_hair], "long_hair")
+        assert_autocomplete_equals(%w[souryuu_asuka_langley], "asuka")
+        assert_autocomplete_equals(%w[crying_with_eyes_open], "open_eyes")
+        assert_autocomplete_equals(%w[open_mouth], "mouth_open")
+        assert_autocomplete_equals(%w[black_hair], "dark")
       end
 
       should "work for an aliased tag" do
+        create(:tag, name: "original")
         create(:tag_alias, antecedent_name: "oc", consequent_name: "original")
 
-        assert_autocomplete_equals(["original"], "oc", "tag_query")
+        assert_autocomplete_equals(["original"], "oc")
       end
 
       should "work for the user: metatag" do
         create(:user, name: "foobar")
 
-        assert_autocomplete_equals(["user:foobar"], "user:foo", "tag_query")
+        assert_autocomplete_equals(["user:foobar"], "user:foo")
       end
 
       should "work for the pool: metatag" do
         as(create(:user)) { create(:pool, name: "foobar") }
 
-        assert_autocomplete_equals(["pool:foobar"], "pool:foo", "tag_query")
+        assert_autocomplete_equals(["pool:foobar"], "pool:foo")
       end
 
       should "work for a missing type" do
+        create(:tag, name: "azur_lane")
+
         get autocomplete_index_path(search: { query: "azur" }), as: :json
 
         assert_response :success
@@ -61,11 +80,16 @@ class AutocompleteControllerTest < ActionDispatch::IntegrationTest
       end
 
       should "work for the AND and OR keywords" do
-        assert_autocomplete_equals(["android"], "and", "tag_query")
-        assert_autocomplete_equals(["original"], "or", "tag_query")
+        create(:tag, name: "android")
+        create(:tag, name: "original")
+
+        assert_autocomplete_equals(["android"], "and")
+        assert_autocomplete_equals(["original"], "or")
       end
 
       should "not set session cookies when the response is publicly cached" do
+        create(:tag, name: "azur_lane")
+
         get autocomplete_index_path(search: { query: "azur", type: "tag_query" })
 
         assert_response :success