diff --git a/app/helpers/admin/action_logs_helper.rb b/app/helpers/admin/action_logs_helper.rb
index 359d60b60e2..e5fbb1500e9 100644
--- a/app/helpers/admin/action_logs_helper.rb
+++ b/app/helpers/admin/action_logs_helper.rb
@@ -9,42 +9,6 @@ module Admin::ActionLogsHelper
     end
   end
 
-  def linkable_log_target(record)
-    case record.class.name
-    when 'Account'
-      link_to record.acct, admin_account_path(record.id)
-    when 'User'
-      link_to record.account.acct, admin_account_path(record.account_id)
-    when 'CustomEmoji'
-      record.shortcode
-    when 'Report'
-      link_to "##{record.id}", admin_report_path(record)
-    when 'DomainBlock', 'EmailDomainBlock'
-      link_to record.domain, "https://#{record.domain}"
-    when 'Status'
-      link_to record.account.acct, TagManager.instance.url_for(record)
-    when 'AccountWarning'
-      link_to record.target_account.acct, admin_account_path(record.target_account_id)
-    end
-  end
-
-  def log_target_from_history(type, attributes)
-    case type
-    when 'CustomEmoji'
-      attributes['shortcode']
-    when 'DomainBlock', 'EmailDomainBlock'
-      link_to attributes['domain'], "https://#{attributes['domain']}"
-    when 'Status'
-      tmp_status = Status.new(attributes.except('reblogs_count', 'favourites_count'))
-
-      if tmp_status.account
-        link_to tmp_status.account&.acct || "##{tmp_status.account_id}", admin_account_path(tmp_status.account_id)
-      else
-        I18n.t('admin.action_logs.deleted_status')
-      end
-    end
-  end
-
   def relevant_log_changes(log)
     if log.target_type == 'CustomEmoji' && [:enable, :disable, :destroy].include?(log.action)
       log.recorded_changes.slice('domain')
@@ -111,4 +75,40 @@ module Admin::ActionLogsHelper
   def opposite_verbs?(log)
     %w(DomainBlock EmailDomainBlock AccountWarning).include?(log.target_type)
   end
+
+  def linkable_log_target(record)
+    case record.class.name
+    when 'Account'
+      link_to record.acct, admin_account_path(record.id)
+    when 'User'
+      link_to record.account.acct, admin_account_path(record.account_id)
+    when 'CustomEmoji'
+      record.shortcode
+    when 'Report'
+      link_to "##{record.id}", admin_report_path(record)
+    when 'DomainBlock', 'EmailDomainBlock'
+      link_to record.domain, "https://#{record.domain}"
+    when 'Status'
+      link_to record.account.acct, TagManager.instance.url_for(record)
+    when 'AccountWarning'
+      link_to record.target_account.acct, admin_account_path(record.target_account_id)
+    end
+  end
+
+  def log_target_from_history(type, attributes)
+    case type
+    when 'CustomEmoji'
+      attributes['shortcode']
+    when 'DomainBlock', 'EmailDomainBlock'
+      link_to attributes['domain'], "https://#{attributes['domain']}"
+    when 'Status'
+      tmp_status = Status.new(attributes.except('reblogs_count', 'favourites_count'))
+
+      if tmp_status.account
+        link_to tmp_status.account&.acct || "##{tmp_status.account_id}", admin_account_path(tmp_status.account_id)
+      else
+        I18n.t('admin.action_logs.deleted_status')
+      end
+    end
+  end
 end
diff --git a/spec/helpers/admin/action_log_helper_spec.rb b/spec/helpers/admin/action_log_helper_spec.rb
new file mode 100644
index 00000000000..d7af6b939e6
--- /dev/null
+++ b/spec/helpers/admin/action_log_helper_spec.rb
@@ -0,0 +1,272 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe Admin::ActionLogsHelper, type: :helper do
+  klass = Class.new do
+    include ActionView::Helpers
+    include Admin::ActionLogsHelper
+  end
+
+  let(:hoge) { klass.new }
+
+  describe '#log_target' do
+    after do
+      hoge.log_target(log)
+    end
+
+    context 'log.target' do
+      let(:log) { double(target: true) }
+
+      it 'calls linkable_log_target' do
+        expect(hoge).to receive(:linkable_log_target).with(log.target)
+      end
+    end
+
+    context '!log.target' do
+      let(:log) { double(target: false, target_type: :type, recorded_changes: :change) }
+
+      it 'calls log_target_from_history' do
+        expect(hoge).to receive(:log_target_from_history).with(log.target_type, log.recorded_changes)
+      end
+    end
+  end
+
+  describe '#relevant_log_changes' do
+    let(:log) { double(target_type: target_type, action: log_action, recorded_changes: recorded_changes) }
+    let(:recorded_changes) { double }
+
+    after do
+      hoge.relevant_log_changes(log)
+    end
+
+    context "log.target_type == 'CustomEmoji' && [:enable, :disable, :destroy].include?(log.action)" do
+      let(:target_type) { 'CustomEmoji' }
+      let(:log_action)  { :enable }
+
+      it "calls log.recorded_changes.slice('domain')" do
+        expect(recorded_changes).to receive(:slice).with('domain')
+      end
+    end
+
+    context "log.target_type == 'CustomEmoji' && log.action == :update" do
+      let(:target_type) { 'CustomEmoji' }
+      let(:log_action)  { :update }
+
+      it "calls log.recorded_changes.slice('domain', 'visible_in_picker')" do
+        expect(recorded_changes).to receive(:slice).with('domain', 'visible_in_picker')
+      end
+    end
+
+    context "log.target_type == 'User' && [:promote, :demote].include?(log.action)" do
+      let(:target_type) { 'User' }
+      let(:log_action)  { :promote }
+
+      it "calls log.recorded_changes.slice('moderator', 'admin')" do
+        expect(recorded_changes).to receive(:slice).with('moderator', 'admin')
+      end
+    end
+
+    context "log.target_type == 'User' && [:change_email].include?(log.action)" do
+      let(:target_type) { 'User' }
+      let(:log_action)  { :change_email }
+
+      it "calls log.recorded_changes.slice('email', 'unconfirmed_email')" do
+        expect(recorded_changes).to receive(:slice).with('email', 'unconfirmed_email')
+      end
+    end
+
+    context "log.target_type == 'DomainBlock'" do
+      let(:target_type) { 'DomainBlock' }
+      let(:log_action)  { nil }
+
+      it "calls log.recorded_changes.slice('severity', 'reject_media')" do
+        expect(recorded_changes).to receive(:slice).with('severity', 'reject_media')
+      end
+    end
+
+    context "log.target_type == 'Status' && log.action == :update" do
+      let(:target_type) { 'Status' }
+      let(:log_action)  { :update }
+
+      it "log.recorded_changes.slice('sensitive')" do
+        expect(recorded_changes).to receive(:slice).with('sensitive')
+      end
+    end
+  end
+
+  describe '#log_extra_attributes' do
+    after do
+      hoge.log_extra_attributes(hoge: 'hoge')
+    end
+
+    it "calls content_tag(:span, key, class: 'diff-key')" do
+      allow(hoge).to receive(:log_change).with(anything)
+      expect(hoge).to receive(:content_tag).with(:span, :hoge, class: 'diff-key')
+    end
+
+    it 'calls safe_join twice' do
+      expect(hoge).to receive(:safe_join).with(
+        ['<span class="diff-key">hoge</span>',
+         '=',
+         '<span class="diff-neutral">hoge</span>']
+      )
+
+      expect(hoge).to receive(:safe_join).with([nil], ' ')
+    end
+  end
+
+  describe '#log_change' do
+    after do
+      hoge.log_change(val)
+    end
+
+    context '!val.is_a?(Array)' do
+      let(:val) { 'hoge' }
+
+      it "calls content_tag(:span, val, class: 'diff-neutral')" do
+        expect(hoge).to receive(:content_tag).with(:span, val, class: 'diff-neutral')
+      end
+    end
+
+    context 'val.is_a?(Array)' do
+      let(:val) { %w(foo bar) }
+
+      it 'calls #content_tag twice and #safe_join' do
+        expect(hoge).to receive(:content_tag).with(:span, 'foo', class: 'diff-old')
+        expect(hoge).to receive(:content_tag).with(:span, 'bar', class: 'diff-new')
+        expect(hoge).to receive(:safe_join).with([nil, nil], '→')
+      end
+    end
+  end
+
+  describe '#icon_for_log' do
+    subject   { hoge.icon_for_log(log) }
+
+    context "log.target_type == 'Account'" do
+      let(:log) { double(target_type: 'Account') }
+
+      it 'returns "user"' do
+        expect(subject).to be 'user'
+      end
+    end
+
+    context "log.target_type == 'User'" do
+      let(:log) { double(target_type: 'User') }
+
+      it 'returns "user"' do
+        expect(subject).to be 'user'
+      end
+    end
+
+    context "log.target_type == 'CustomEmoji'" do
+      let(:log) { double(target_type: 'CustomEmoji') }
+
+      it 'returns "file"' do
+        expect(subject).to be 'file'
+      end
+    end
+
+    context "log.target_type == 'Report'" do
+      let(:log) { double(target_type: 'Report') }
+
+      it 'returns "flag"' do
+        expect(subject).to be 'flag'
+      end
+    end
+
+    context "log.target_type == 'DomainBlock'" do
+      let(:log) { double(target_type: 'DomainBlock') }
+
+      it 'returns "lock"' do
+        expect(subject).to be 'lock'
+      end
+    end
+
+    context "log.target_type == 'EmailDomainBlock'" do
+      let(:log) { double(target_type: 'EmailDomainBlock') }
+
+      it 'returns "envelope"' do
+        expect(subject).to be 'envelope'
+      end
+    end
+
+    context "log.target_type == 'Status'" do
+      let(:log) { double(target_type: 'Status') }
+
+      it 'returns "pencil"' do
+        expect(subject).to be 'pencil'
+      end
+    end
+  end
+
+  describe '#class_for_log_icon' do
+    subject   { hoge.class_for_log_icon(log) }
+
+    %i(enable unsuspend unsilence confirm promote resolve).each do |action|
+      context "log.action == #{action}" do
+        let(:log) { double(action: action) }
+
+        it 'returns "positive"' do
+          expect(subject).to be 'positive'
+        end
+      end
+    end
+
+    context 'log.action == :create' do
+      context 'opposite_verbs?(log)' do
+        let(:log) { double(action: :create, target_type: 'DomainBlock') }
+
+        it 'returns "negative"' do
+          expect(subject).to be 'negative'
+        end
+      end
+
+      context '!opposite_verbs?(log)' do
+        let(:log) { double(action: :create, target_type: '') }
+
+        it 'returns "positive"' do
+          expect(subject).to be 'positive'
+        end
+      end
+    end
+
+    %i(update reset_password disable_2fa memorialize change_email).each do |action|
+      context "log.action == #{action}" do
+        let(:log) { double(action: action) }
+
+        it 'returns "neutral"' do
+          expect(subject).to be 'neutral'
+        end
+      end
+    end
+
+    %i(demote silence disable suspend remove_avatar remove_header reopen).each do |action|
+      context "log.action == #{action}" do
+        let(:log) { double(action: action) }
+
+        it 'returns "negative"' do
+          expect(subject).to be 'negative'
+        end
+      end
+    end
+
+    context 'log.action == :destroy' do
+      context 'opposite_verbs?(log)' do
+        let(:log) { double(action: :destroy, target_type: 'DomainBlock') }
+
+        it 'returns "positive"' do
+          expect(subject).to be 'positive'
+        end
+      end
+
+      context '!opposite_verbs?(log)' do
+        let(:log) { double(action: :destroy, target_type: '') }
+
+        it 'returns "negative"' do
+          expect(subject).to be 'negative'
+        end
+      end
+    end
+  end
+end