Implement SiteSetting to allow anonymous liking

config/site_settings.yml

@@ -664,6 +664,9 @@ users:
   allow_anonymous_posting:
     default: false
     client: true
+  allow_anonymous_likes:
+    default: false
+    client: true
   anonymous_posting_min_trust_level:
     default: 1
     enum: "TrustLevelSetting"

lib/guardian/post_guardian.rb

@@ -43,7 +43,10 @@ def post_can_act?(post, action_key, opts: {}, can_see_post: nil)
     already_did_flagging = taken.any? && (taken & PostActionType.notify_flag_types.values).any?
 
     result =
-      if authenticated? && post && !@user.anonymous?
+      if authenticated? && post
+        # Allow anonymous users to like if feature is enabled and short-circuit otherwise
+        return SiteSetting.allow_anonymous_likes? && (action_key == :like) if @user.anonymous?
+
         # Silenced users can't flag
         return false if is_flag && @user.silenced?
 

spec/lib/guardian_spec.rb

@@ -98,6 +98,38 @@
     fab!(:user) { Fabricate(:user) }
     fab!(:post) { Fabricate(:post) }
 
+    describe "an anonymous user" do
+      before { SiteSetting.allow_anonymous_posting = true }
+
+      context "when allow_anonymous_likes is enabled" do
+        before { SiteSetting.allow_anonymous_likes = true }
+
+        it "returns true when liking" do
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :like)).to be_truthy
+        end
+
+        it "cannot perform any other action" do
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :flag)).to be_falsey
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :bookmark)).to be_falsey
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :notify_user)).to be_falsey
+        end
+      end
+
+      context "when allow_anonymous_likes is disabled" do
+        before { SiteSetting.allow_anonymous_likes = false }
+
+        it "returns false when liking" do
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :like)).to be_falsey
+        end
+
+        it "cannot perform any other action" do
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :flag)).to be_falsey
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :bookmark)).to be_falsey
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :notify_user)).to be_falsey
+        end
+      end
+    end
+
     it "returns false when the user is nil" do
       expect(Guardian.new(nil).post_can_act?(post, :like)).to be_falsey
     end