From https://once.com/writebook

test/controllers/pictures_controller_test.rb

@@ -0,0 +1,41 @@
+require "test_helper"
+
+class PicturesControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    sign_in :kevin
+  end
+
+  test "update picture" do
+    get edit_leafable_path(leaves(:reading_picture))
+    assert_response :ok
+
+    put leafable_path(leaves(:reading_picture)), params: {
+      leaf: { title: "New picture" },
+      picture: {
+        image: fixture_file_upload("white-rabbit.webp", "image/webp")
+      } }
+
+    assert_response :no_content
+
+    updated_picture = Picture.last
+    assert_equal "New picture", updated_picture.title
+    assert_equal "white-rabbit.webp", updated_picture.image.filename.to_s
+  end
+
+  test "update caption" do
+    get edit_leafable_path(leaves(:reading_picture))
+    assert_response :ok
+
+    put leafable_path(leaves(:reading_picture)), params: {
+      picture: {
+        caption: "New caption"
+      } }
+
+    assert_response :no_content
+
+    updated_picture = Picture.last
+
+    assert_equal "New caption", updated_picture.caption
+    assert_equal "reading.webp", updated_picture.image.filename.to_s
+  end
+end