fixed test env

Author: jonasjabari

Dockerfile.test

@@ -1,9 +1,9 @@
-FROM ruby:3.0-alpine3.12
+FROM ruby:2.7.2-alpine3.12
 
 RUN gem install bundler:2.1.4
 
 RUN apk update --no-cache && \
-    apk add build-base postgresql-dev git nodejs yarn tzdata bash sqlite-dev && \
+    apk add build-base postgresql-dev git nodejs yarn tzdata bash sqlite-dev npm && \
     mkdir -p /app
 
 WORKDIR /app

spec/dummy/app/matestack/app.rb

@@ -0,0 +1,8 @@
+# used within specs only
+class App < Matestack::Ui::App
+
+  def response
+    yield
+  end
+
+end