Add API for tagging cards

test/controllers/cards/taggings_controller_test.rb

@@ -23,4 +23,26 @@ class Cards::TaggingsControllerTest < ActionDispatch::IntegrationTest
       assert_turbo_stream action: :replace, target: dom_id(cards(:logo), :tags)
     end
   end
+
+  test "toggle tag on as JSON" do
+    card = cards(:logo)
+
+    assert_not card.tagged_with?(tags(:mobile))
+
+    post card_taggings_path(card), params: { tag_title: tags(:mobile).title }, as: :json
+
+    assert_response :no_content
+    assert card.reload.tagged_with?(tags(:mobile))
+  end
+
+  test "toggle tag off as JSON" do
+    card = cards(:logo)
+
+    assert card.tagged_with?(tags(:web))
+
+    post card_taggings_path(card), params: { tag_title: tags(:web).title }, as: :json
+
+    assert_response :no_content
+    assert_not card.reload.tagged_with?(tags(:web))
+  end
 end